Continuous enhanced washing desalination system and method for waste incineration fly ash

Abstract

The invention discloses a continuous enhanced washing desalination system and method for waste incineration fly ash, the system comprises at least three washing units which are connected in series, each washing unit comprises a washing tank, a hydrodynamic cavitator, a circulating pump, a first mud-water separator and a second mud-water separator which are communicated to form two sections of external circulating pipelines, and a washing liquid recycling pipeline is formed. The invention further discloses a method for treating the waste incineration fly ash through the system. According to the washing desalination system disclosed by the invention, deep elution desalination treatment is carried out on fly ash by adopting continuous three-stage stirring washing, two-stage forced circulation strengthening and two-stage mud-water separation, so that the desalination treatment on the fly ash can be efficiently and thoroughly completed on the premise of effectively reducing the water consumption; the device has the advantages of being simple in equipment, easy and convenient to operate, small in occupied area, low in cost, water consumption and energy consumption, high in elution efficiency, wide in application range, capable of continuously running, good in running stability and the like, and has an important promoting effect on reduction and resource utilization of the fly ash.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste disposal, and relates to a water washing system and method for waste incineration fly ash, and specifically to a continuous enhanced water washing and desalination system and method for waste incineration fly ash. Background Art

[0002] In the fly ash from garbage incineration (referred to as fly ash), inorganic salts such as potassium salts, sodium salts and soluble calcium salts account for about 40-50% of the total fly ash. Among them, chloride salts such as sodium chloride, potassium chloride, calcium chloride, and some sulfates and alkalis have certain economic value and are suitable for resource recovery. Therefore, it is necessary to reduce and recover the fly ash from garbage incineration.

[0003] At present, water washing and desalination of fly ash is the mainstream technology for fly ash reduction and resource processing at this stage. Among them, effective elution of fly ash salt is the primary problem of fly ash reduction and resource utilization. The elution effect and water consumption / energy consumption are the main contradictions that must be overcome in the fly ash resource process. In order to promote water washing mass transfer, enhanced stirring and countercurrent water washing are often used to increase the dissolution rate of chloride salts. At the same time, in order to ensure the elution effect of fly ash salts, the existing water washing technology often uses a multi-stage (countercurrent) water washing process for gradient elution. At the same time, the next-level water washing liquid that has been separated from mud and water is used to supplement the previous-level water washing liquid to reduce the demand for water, and then the water washing liquid is separated and salt is extracted to achieve fly ash reduction and resource utilization. However, the existing conventional water washing desalination methods or equipment still have the following defects: (1) In order to solve the problem of slow dissolution and mass transfer of soluble salts in water washing, in order to promote salt dissolution, the existing technical solutions generally adopt solutions such as increasing the speed or size of the stirring paddle, increasing the amount of clean water in the system, etc., but these solutions are often prone to causing excessive load on the stirring machinery, excessive volume of the stirring tank, and prolonged system residence time. (2) In order to solve the problems of large water consumption in the fly ash water washing process, large amount of high-concentration brine treatment at the back end, and high energy consumption, the existing technology usually reuses the clean water after the concentrated brine treatment to alleviate the water demand, and reuses the heat energy of the evaporation process to reduce energy consumption, but this technical idea does not solve the problem of excessive water consumption in the whole process and excessive evaporation volume of concentrated brine. (3) In the existing fly ash washing process, in order to improve the desalination rate of each level of washing, it is necessary to carry out efficient dehydration treatment in each link of the washing process. At present, centrifugal dehydration + plate and frame dehydration or multi-stage plate and frame dehydration process is mainly used to increase the solid content of the dehydrated material to improve the desalination rate. However, the feeding and discharging and operation requirements of the above equipment cause the various processes including feeding, discharging, sedimentation mud and water separation and secondary / tertiary fly ash feeding to be discontinuous and the equipment to be complicated. At the same time, feeding, discharging, sedimentation and dehydration are intermittent operations, and the operation efficiency is low. (4) The existing fly ash washing process has a long waiting time for feeding, discharging, sedimentation and dehydration, and there are problems such as complicated equipment types, large number, large volume and high energy consumption. (5) In the dehydration process of the existing fly ash washing process, due to the fine size of the fly ash slurry, the fly ash is easy to flow out with the water or pass through the filter cloth during the centrifugal plate and frame dehydration process. Therefore, the existing technology usually requires the slurry to be flocculated + sedimentation + centrifugal dehydration before plate and frame dehydration. The process is too long, and there is still a lot of fly ash that will pass through the filter cloth. (6) The existing multi-stage fly ash washing process is not adaptable to the properties of fly ash of different qualities, resulting in poor applicability of the process. (7) The intermittent feeding used in the existing fly ash washing process and equipment includes multiple control methods, such as weight / pressure / time control logic used in each stage of the mixing tank, time / liquid level control used in the temporary storage tank, sedimentation tank, etc., liquid level / speed / pressure / time control used in the centrifugal / plate and frame intermittent dehydration, and time control used in the sludge intermittent conveying part. Too many control methods lead to excessive complexity of the process and equipment, poor operating stability, low processing efficiency, and are not conducive to industrial utilization.

[0004] Therefore, how to effectively overcome the defects or shortcomings existing in the above-mentioned prior art, such as discontinuous operation of material input and output and / or intermediate processes and long residence time, low elution efficiency and high water consumption, large number and complexity of equipment, high equipment cost and large footprint, large total amount of water washing liquid processed and high processing energy consumption, and poor adaptability, is of great significance for promoting the reduction and resource utilization of waste incineration fly ash. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a continuous enhanced water washing and desalination system and method for waste incineration fly ash with simple equipment, simple operation, small footprint, low cost, low water consumption, low energy consumption, high elution efficiency, wide range of applications, continuous operation and good operating stability in response to the shortcomings of the prior art.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A continuous enhanced water washing and desalination system for waste incineration fly ash, comprising at least three water washing units connected in series;

[0008] The water washing unit comprises a water washing tank, a hydraulic cavitation device, a circulation pump, a first mud-water separator and a second mud-water separator; the discharge port of the water washing tank is communicated with the inlet of the hydraulic cavitation device through a first valve, and the outlet of the hydraulic cavitation device is communicated with the inlet of the circulation pump; the outlet of the circulation pump is communicated with the feed port of the first mud-water separator through a second valve; the water outlet of the first mud-water separator is communicated with the first hydraulic cavitation aeration port located in the middle of the water washing tank through a third valve; the water outlet of the first mud-water separator is communicated with the feed port of the second mud-water separator through a fourth valve; the water outlet of the second mud-water separator is communicated with the second hydraulic cavitation aeration port located in the upper part of the water washing tank through a sixth valve;

[0009] In two adjacent water washing units, the discharge port of the first mud-water separator in the previous water washing unit is connected to the feed port of the water washing tank in the next water washing unit through the fifth valve, and the discharge port of the second mud-water separator in the previous water washing unit is connected to the feed port of the water washing tank in the next water washing unit through the seventh valve;

[0010] In two adjacent water washing units, the water outlet of the second mud-water separator in the latter water washing unit is connected to the water inlet of the water washing tank in the former water washing unit through the eighth valve.

[0011] As a further improvement of the above technical solution: each of the water washing tanks is also provided with a stirrer; the water inlet of each of the water washing tanks is also connected to a water inlet pipe; the feed inlet of each of the water washing tanks is also connected to a fly ash storage tank.

[0012] As a further improvement of the above technical solution: the first water washing unit also includes a first material tank (for storing auxiliary materials) and a second material tank (for storing auxiliary materials), and the outlets of the first material tank and the second material tank are respectively connected to the feed port of the water washing tank; a ninth valve is provided on the pipeline between the first material tank and the water washing tank; a tenth valve is provided on the pipeline between the second material tank and the water washing tank.

[0013] As a further improvement of the above technical solution: the first mud-water separator is a cyclone; the second mud-water separator is a cyclone.

[0014] As a further improvement of the above technical solution: the eighth valve of the first water washing unit is also connected to a water outlet pipe; starting from the third water washing unit, the fifth valve and the seventh valve of the water washing unit are respectively connected to mud discharge pipes.

[0015] As a general technical concept, the present invention also provides a method for continuous enhanced water washing and desalination of waste incineration fly ash, and the waste incineration fly ash is treated by using the above-mentioned continuous enhanced water washing and desalination system.

[0016] As a further improvement of the above technical solution: the above continuous enhanced water washing desalination method comprises the following steps:

[0017] (1) Adding fly ash and water from garbage incineration into the water washing tank of the first water washing unit, opening the first valve, the hydraulic cavitation device, the circulating pump, the second valve, the first mud-water separator, the third valve, the fourth valve, the sixth valve and the second mud-water separator, respectively, and performing a first-stage circulating elution and a second-stage circulating elution on the slurry in the middle and upper parts of the water washing tank. During the circulating elution process, opening the fifth valve and the seventh valve, and sending the primary water-washed ash produced in the first mud-water separator and the second mud-water separator into the water washing tank of the second water washing unit;

[0018] (2) adding water to the water washing tank of the second water washing unit, opening the first valve, the hydrodynamic cavitation device, the circulation pump, the second valve, the first mud-water separator, the third valve, the fourth valve, the sixth valve and the second mud-water separator, respectively performing a first-stage circulation elution and a second-stage circulation elution on the slurry in the middle and upper parts of the water washing tank. During the circulation elution process, opening the fifth valve and the seventh valve, and sending the secondary water-washed ash produced in the first mud-water separator and the second mud-water separator to the water washing tank of the third water washing unit;

[0019] (3) Add water to the washing tank of the third washing unit, open the first valve, the hydraulic cavitation device, the circulation pump, the second valve, the first mud-water separator, the third valve, the fourth valve, the sixth valve and the second mud-water separator, and perform a first-stage circulation elution and a second-stage circulation elution on the slurry in the middle and upper parts of the washing tank respectively. During the circulation elution process, open the fifth valve and the seventh valve to discharge the tertiary water-washed ash produced in the first mud-water separator and the second mud-water separator, thereby completing the treatment of the waste incineration fly ash.

[0020] As a further improvement of the above technical solution: in step (1), the liquid-to-solid ratio of the slurry in the water washing tank is 2.0-2.5:1; the residence time of the waste incineration fly ash in the first water washing unit is 6min-10min; the primary water washing liquid produced in the second mud-water separator is discharged outward through the eighth valve and the outlet pipe; the conductivity of the primary water washing liquid is ≥260mS / cm; the subsequent treatment of the primary water washing liquid includes: recovering sodium salt and potassium salt from the primary water washing liquid; the process parameters of the hydraulic cavitation device are: cavitation number is 0.7-1.2, or flow rate control is adopted, the orifice plate diameter is 4mm-6mm, and the flow rate is 5m / s-7m / s; the total circulation flow rate of the material in the first water washing unit is 2m / s-4m / s; the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution is 3-5:1.

[0021] As a further improvement of the above technical solution: in step (2), the liquid-to-solid ratio of the slurry in the water washing tank is 2.0-2.5:1; the residence time of the primary water-washed ash in the second water washing unit is 6min-8min; the secondary water washing liquid produced in the second mud-water separator is introduced into the water washing tank of the first water washing unit through the eighth valve; the conductivity of the secondary water washing liquid is 40mS / cm-60mS / cm; the process parameters of the hydraulic cavitation device are: the cavitation number is 0.7-1.2, or flow rate control is adopted, the orifice plate diameter is 4mm-6mm, and the flow rate is 5m / s-7m / s; the total circulation flow rate of the material in the second water washing unit is 2m / s-4m / s; the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution is 3-5:1.

[0022] As a further improvement of the above technical solution: in step (3), the liquid-to-solid ratio of the slurry in the water washing tank is 2.0-2.5:1; the residence time of the secondary water-washed ash in the third water washing unit is 4-6 minutes; the tertiary water washing liquid produced in the second mud-water separator is introduced into the water washing tank of the second water washing unit through the eighth valve; the conductivity of the tertiary water washing liquid is 5mS / cm-10mS / cm; the subsequent treatment of the tertiary water-washed ash is: dehydrating the tertiary water-washed ash to obtain a dehydrated Ash and filtrate; the moisture content of the dehydrated ash is 30% to 35%; the chlorine content in the dehydrated ash is ≤0.5%; the filtrate is used as water replenishment and refluxed into the water washing tank; the process parameters of the hydraulic cavitation device are: the cavitation number is 0.7 to 1.2, or flow rate control is adopted, the orifice plate diameter is 4mm to 6mm, and the flow rate is 5m / s to 7m / s; the total circulation flow rate of the material in the third water washing unit is 2m / s to 4m / s; the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution is 3 to 5:1.

[0023] As a further improvement of the above technical solution: the above continuous enhanced water washing desalination method comprises the following steps:

[0024] S1. Continuously add waste incineration fly ash and water to the water washing tank of the first water washing unit, open the first valve, hydraulic cavitation device, circulation pump, second valve, first mud-water separator, third valve, fourth valve, sixth valve and second mud-water separator, respectively perform one-stage circulation elution and two-stage circulation elution on the slurry in the middle and upper parts of the water washing tank, and during the circulation elution process, open the fifth valve and the seventh valve to feed the primary water-washed ash produced in the first mud-water separator and the second mud-water separator into the water washing tank of the second water washing unit;

[0025] S2, opening the first valve, the hydrodynamic cavitation device, the circulation pump, the second valve, the first mud-water separator, the third valve, the fourth valve, the sixth valve and the second mud-water separator of the second water washing unit, respectively performing a first-stage circulation elution and a second-stage circulation elution on the slurry in the middle and upper parts of the water washing tank. During the circulation elution process, opening the fifth valve and the seventh valve, feeding the secondary water-washed ash produced in the first mud-water separator and the second mud-water separator into the water washing tank of the third water washing unit, opening the eighth valve, feeding the secondary water washing liquid produced in the first mud-water separator and the second mud-water separator into the water washing tank of the first water washing unit;

[0026] S3, opening the first valve, the hydrodynamic cavitation device, the circulation pump, the second valve, the first mud-water separator, the third valve, the fourth valve, the sixth valve and the second mud-water separator of the third water washing unit, respectively performing a first-stage circulation elution and a second-stage circulation elution on the slurry in the middle and upper parts of the water washing tank. During the circulation elution process, opening the eighth valve, sending the tertiary water washing liquid produced in the first mud-water separator and the second mud-water separator into the water washing tank of the second water washing unit, opening the fifth valve and the seventh valve, and discharging the tertiary water-washed ash produced in the first mud-water separator and the second mud-water separator;

[0027] S4. Repeat steps S1 to S3 to continuously process the waste incineration fly ash.

[0028] As a further improvement of the above technical solution: in step S1, the liquid-to-solid ratio of the slurry in the water washing tank is 2.0-2.5:1; the residence time of the waste incineration fly ash in the first water washing unit is 6min-10min; the primary water washing liquid produced in the second mud-water separator is discharged outward through the eighth valve and the outlet pipe; the conductivity of the primary water washing liquid is ≥260mS / cm; the subsequent treatment of the primary water washing liquid includes: recovering sodium salt and potassium salt from the primary water washing liquid; the process parameters of the hydraulic cavitation device are: cavitation number is 0.7-1.2, or flow rate control is adopted, the orifice plate diameter is 4mm-6mm, and the flow rate is 5m / s-7m / s; the total circulation flow rate of the material in the first water washing unit is 2m / s-4m / s; the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution process is 3-5:1.

[0029] As a further improvement of the above technical solution: in step S2, the liquid-to-solid ratio of the slurry in the water washing tank is 2.0-2.5:1; the residence time of the primary water-washed ash in the second water washing unit is 4-8 minutes; the conductivity of the secondary water washing liquid is 40-60 mS / cm; the process parameters of the hydrodynamic cavitation device are: the cavitation number is 0.7-1.2, or the flow rate is controlled by the flow rate, the orifice plate diameter is 4-6 mm, and the flow rate is 5-7 m / s; the total circulation flow rate of the material in the second water washing unit is 2-4 m / s; the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution is 3-5:1;

[0030] As a further improvement of the above technical solution: in step S3, the liquid-to-solid ratio of the slurry in the water washing tank is 2.0-2.5:1; the residence time of the secondary water-washed ash in the third water washing unit is 4-6 minutes; the conductivity of the tertiary water washing liquid is 5mS / cm-10mS / cm; the subsequent treatment of the tertiary water-washed ash is: dehydrating the tertiary water-washed ash to obtain dehydrated ash and filtrate; the moisture content of the dehydrated ash is 30% ~35%; the chlorine content in the dehydrated ash is ≤0.5%; the filtrate is used as make-up water and refluxed into the water washing tank; the process parameters of the hydraulic cavitation device are: the cavitation number is 0.7-1.2, or flow rate control is adopted, the orifice plate diameter is 4mm-6mm, and the flow rate is 5m / s-7m / s; the total circulation flow rate of the material in the third water washing unit is 2m / s-4m / s; the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution is 3-5:1.

[0031] Compared with the prior art, the advantages of the present invention are:

[0032] (1) In view of the shortcomings of the existing water washing equipment, such as the excessively high mechanical load of the stirring machine, the excessively large volume of the stirring tank, and the prolonged system residence time, in the continuous enhanced water washing and desalination system for waste incineration fly ash of the present invention, each level of the water washing unit adopts the method of "stirring water washing + hydraulic cavitation enhanced dispersion contact + initial stage forced circulation enhanced mass transfer + second stage forced circulation increased reflux water-ash ratio" to perform three-stage mass transfer enhancement, which significantly promotes the dissolution of salt. The first mass transfer enhancement is to use the high-speed shear flushing of the hydraulic cavitation device to achieve thorough dispersion and slurrying of the material. At the same time, the violent disturbance in the hydraulic cavitation process is likely to produce local high temperature, that is, the water phase combustion produces micro-area high temperature, which realizes the shear refinement and enhanced dispersion contact between particles and the temperature rise to promote Dissolution; The second and third mass transfer enhancements are two-stage forced circulations realized by a circulating pump. The first stage forced circulation utilizes an external circulation to enhance mass transfer, and enhanced mass transfer dissolution is performed in the pipeline, and preliminary mud and water separation is performed. A portion of the water phase after mud and water separation is returned to the water washing tank through the first hydraulic cavitation aeration port set in the middle of the water washing tank, which can also rinse the slurry in the middle of the water washing tank while improving the water-cement ratio in the tank; another portion of the water phase after mud and water separation enters the second stage forced circulation for treatment, and the material is further enhanced in mass transfer and salty water is removed through the second stage forced circulation. The washing liquid that has undergone continuous mud and water separation is partially returned to further improve the water-cement ratio in the tank, and the process does not require external water. It can be seen that in the continuous enhanced water washing and desalination system for waste incineration fly ash of the present invention, each level of water washing unit utilizes structural and process innovation design to perform three times of enhanced water washing mass transfer, two cycles to increase the water-cement ratio, and two dehydration and desalination, and the process can achieve enhanced elution and efficient desalination without the need for additional water replenishment. At the same time, the two-stage forced circulation of each level of water washing also serves as an external circulation pipeline, and the material can be washed with water for multiple cycles at the same level, and the single-stage water washing equipment can realize continuous and adjustable multiple water washing operations. Therefore, in the continuous enhanced water washing and desalination system for waste incineration fly ash of the present invention, the external circulation of 3 stages × 2 stages can be used on the basis of the three-stage water washing equipment to realize the continuous adjustable water washing stage, and the effect is obviously better than the three-stage independent water washing.

[0033] (2) Aiming at the problems of excessive water consumption in the whole process and excessive evaporation of concentrated brine in the existing fly ash washing process, the continuous enhanced water washing and desalination system for waste incineration fly ash of the present invention is provided with two sets of external circulation pipelines on each water washing tank, so that each water washing tank has two-stage forced circulation with different functions, thereby strengthening the dissolution of salt in the water washing process, increasing the salt content of the liquid phase, and reducing the process water replenishment amount from the source, wherein the conductivity of the primary water washing liquid can reach more than 260mS / cm, which is significantly higher than the conductivity of the primary water washing liquid in the existing fly ash washing process (180-210mS / cm); further, due to the effective dissolution of salt, the salt content of the water washing liquid is increased, the total amount of concentrated water is reduced, and the water consumption and energy consumption of the system can be reduced. At the same time, in the present invention, by setting two sets of external circulation pipelines, it is also possible to combine the existing clean water reuse and evaporation heat reuse to further save energy and reduce consumption. In addition, in the present invention, by adjusting the two-stage forced circulation of each level of water washing links, it is beneficial to adjust the system to enhance mass transfer and reflux ratio. Therefore, the continuous enhanced water washing and desalination system for waste incineration fly ash of the present invention can effectively increase the salt content in the washing liquid, obtain a washing liquid with a higher salt content, and can effectively reduce the amount of concentrated brine generated, thus having a good water-saving advantage.

[0034] (3) The existing fly ash washing process requires efficient dehydration treatment in each link of the washing process, and has the defects of discontinuous processes at each level, low operating efficiency, and complicated equipment. In this regard, the continuous enhanced washing and desalination system for waste incineration fly ash of the present invention can be tested by continuous feeding + continuous washing + online mud and water separation + continuous discharging. Specifically, in order to achieve the continuity of each link of the process, in the primary washing unit (the first washing unit), the primary washing feed adopts a continuous feeding method to put the material into the washing tank. The washing tank operates continuously, and the fly ash and water are mixed evenly by stirring to form a slurry. The slurry is subjected to initial enhanced washing and desalination and preliminary mud and water separation through a forced circulation and a mud and water separator. On the one hand, It can improve the solid content of the slurry output. On the other hand, a part of the effluent after the initial mud and water separation is returned to the water washing tank for primary circulating water washing, thereby tapping the dissolution potential of the washing liquid and reducing water consumption. Furthermore, another part of the effluent after the initial mud and water separation enters the second-stage forced circulation for secondary enhanced elution and desalination and secondary mud and water separation, thereby further improving the solid content of the slurry output and effectively reducing the transfer of soluble salts in the slurry to the secondary water washing. At the same time, a part of the effluent after the secondary mud and water separation is returned to the water washing tank for primary circulating water washing, thereby further tapping the dissolution potential of the washing liquid and reducing water consumption. Another part of the effluent after the secondary mud and water separation is discharged as high-concentration salt-containing produced water, and is recycled through deep treatment. In the next-stage washing unit (the second washing unit), the feed is the dewatered slurry discharge of the first-stage washing (the washed slurry after two mud-water separations), and continuous feeding is adopted by a slurry pump, etc. The washing tank in the second-stage washing unit operates continuously, similar to the first-stage washing unit. Therefore, in the second-stage washing unit, the solid content of the discharge can be further reduced, and the transfer of soluble salts in the slurry to the tertiary washing is effectively reduced, and more dissolution potential of the washing liquid is excavated to further reduce water consumption. In particular, the washing liquid after two mud-water separations in the second-stage washing unit can be used as replenishment water and refluxed to the washing tank of the first-stage washing unit, which can significantly reduce the water consumption of the system. Finally, in the tertiary washing unit, it also has the effects of increasing the solid content of the slurry discharge and reducing the water consumption of the system. In particular, the salt content and chlorine content in the washed ash after the tertiary washing are significantly reduced. Therefore, the continuous enhanced water washing and desalination system for waste incineration fly ash of the present invention promotes dissolution and reduces water consumption through two-stage forced circulation at each stage, reduces the backward transfer of salt in the ash slurry through two-stage mud-water separation and dehydration at each stage, and realizes continuous operation of all links of the system through a continuous mud-water separator.

[0035] (4) In view of the problems of long waiting time for material inlet and outlet, sedimentation and dehydration in the existing fly ash washing process, complicated equipment types, large number, large volume and high energy consumption, the continuous enhanced water washing and desalination system for waste incineration fly ash of the present invention includes three water washing units, and each water washing unit is provided with two groups of continuously feeding mud-water separators. By adopting two groups of continuously feeding mud-water separators for mud-water separation, the solid content of the material can be quickly improved, and the slurry material only needs to be subjected to deep treatment such as centrifugal dehydration / vacuum dehydration after the mud-water separation of the third-stage water-washed slurry, which is beneficial to improving the stability of the continuous operation of the process and shortening the waiting time, so that the operation efficiency is significantly improved, and the requirements for the number / volume / energy consumption / land area of ​​equipment can be reduced, so that the construction and operation costs are greatly reduced; at the same time, the water-washed slurry is subjected to gradient dehydration using two groups of continuously feeding mud-water separators, so that the effective separation of slurry particles of different particle sizes and the liquid phase can be achieved, which is beneficial to improving the mud-water separation effect and efficiency, ensuring that the SS content in the water phase is low, and facilitating the reuse of the water phase.

[0036] (5) The existing fly ash washing process has shortcomings in the dehydration process, such as the process is too long and small particles of fly ash can easily pass through the filter cloth into the water phase. The continuous enhanced water washing and desalination system for waste incineration fly ash of the present invention, by setting a mud-water separator and combining it with an external circulation pipeline, can return the remaining fly ash in the water phase of each level of water washing unit to the water washing tank and separate it multiple times, which can improve the mud-water separation efficiency and the solid content of the material. Further, by performing subsequent dehydration treatment on the material with a high solid content, the problem of fly ash entrainment and passing through the filter cloth during the dehydration process can be effectively alleviated, and the mud-water separation efficiency can be further improved.

[0037] (6) In view of the problem that the existing multi-stage water washing process for fly ash is not sufficiently adaptable to the properties of fly ash of different qualities, in the present invention, the mutual coordination between the two-stage forced circulation pipelines at each level set in the water washing units at each level can effectively adjust the water washing reflux ratio at each level, thereby realizing flexible adjustment of the number of fly ash water washing cycles, and thus actually achieving stepless and continuous adjustment of fly ash washing without increasing the number of equipment and the area occupied.

[0038] (7) In view of the problem that the prior art intermittent feeding uses weight / pressure / time control logic in each stage of the mixing tank, time / liquid level control in the temporary storage tank, sedimentation tank, etc., liquid level / speed / pressure / time control in the centrifugal / plate and frame intermittent dehydration, and time control in the sludge intermittent conveying part, the control methods are too complicated. In the present invention, the control methods are simplified to conductivity control of the salt content of the washing liquid at each stage + two-stage forced circulation flow control at each stage + moisture content control of the tail end of the third stage washing. The equipment is small, the real-time online control is greatly simplified, the signal feedback is simpler, the control method is more intuitive, the operation is more stable, and the efficiency is greatly improved.

[0039] It can be seen that the continuous enhanced water washing and desalination system for waste incineration fly ash of the present invention, by adopting continuous three-stage stirring water washing, two-stage forced circulation enhancement, and two-stage mud-water separation to carry out deep washing and desalination treatment of fly ash, can efficiently and thoroughly complete the desalination treatment of fly ash under the premise of effectively reducing water consumption, has the advantages of simple equipment, easy operation, small footprint, low cost, low water consumption, low energy consumption, high washing efficiency, wide application range, continuous operation and good operation stability, etc., is a new fly ash water washing and desalination system that can be widely used, has high use value, good application prospects, and plays an important role in promoting the reduction and resource utilization of fly ash. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0041] Figure 1 This is a schematic diagram of the structure of the continuous enhanced water washing and desalination system for waste incineration fly ash in Example 1 of the present invention.

[0042] 1. Washing tank; 11. First valve; 12. Second valve; 13. Third valve; 14. Fourth valve; 15. Fifth valve; 16. Sixth valve; 17. Seventh valve; 18. Eighth valve; 19. Ninth valve; 20. Tenth valve; 2. Hydrodynamic cavitation device; 3. Circulation pump; 41. First mud-water separator; 42. Second mud-water separator; 5. First material tank; 6. Second material tank; 7. Agitator. DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0044] The materials and instruments used in the following examples are all commercially available.

[0045] Embodiment 1:

[0046] like Figure 1 As shown, the continuous enhanced water washing and desalination system for waste incineration fly ash of this embodiment includes three water washing units connected in series;

[0047] In this embodiment, the water washing unit includes a water washing tank 1, a hydraulic cavitation device 2, a circulation pump 3, a first mud-water separator 41 and a second mud-water separator 42; the discharge port of the water washing tank 1 is connected to the inlet of the hydraulic cavitation device 2 through a first valve 11, and the outlet of the hydraulic cavitation device 2 is connected to the inlet of the circulation pump 3; the outlet of the circulation pump 3 is connected to the feed port of the first mud-water separator 41 through a second valve 12; the water outlet of the first mud-water separator 41 is connected to the first hydraulic cavitation aeration port located in the middle of the water washing tank 1 through a third valve 13; the water outlet of the first mud-water separator 41 is connected to the feed port of the second mud-water separator 42 through a fourth valve 14; the water outlet of the second mud-water separator 42 is connected to the second hydraulic cavitation aeration port located at the upper part of the water washing tank 1 through a sixth valve 16;

[0048] In two adjacent water washing units, the discharge port of the first mud-water separator 41 in the previous water washing unit is connected to the feed port of the water washing tank 1 in the next water washing unit through the fifth valve 15, and the discharge port of the second mud-water separator 42 in the previous water washing unit is connected to the feed port of the water washing tank 1 in the next water washing unit through the seventh valve 17;

[0049] In two adjacent water washing units, the water outlet of the second mud-water separator 42 in the latter water washing unit is connected to the water inlet of the water washing tank 1 in the former water washing unit through the eighth valve 18.

[0050] In this embodiment, each water washing tank 1 is further provided with a stirrer 7; the water inlet of each water washing tank 1 is also connected to a water inlet pipe; and the feed inlet of each water washing tank 1 is also connected to a fly ash storage tank.

[0051] In this embodiment, the first water washing unit also includes a first material tank 5 and a second material tank 6, and the outlets of the first material tank 5 and the second material tank 6 are respectively connected to the feed port of the water washing tank 1; a ninth valve 19 is provided on the pipeline between the first material tank 5 and the water washing tank 1; and a tenth valve 20 is provided on the pipeline between the second material tank 6 and the water washing tank 1.

[0052] In this embodiment, the first mud-water separator 41 is a cyclone; the second mud-water separator 42 is a cyclone.

[0053] In this embodiment, the eighth valve 18 of the first water washing unit is also connected to a water outlet pipe.

[0054] In this embodiment, the fifth valve 15 and the seventh valve 17 of the third water washing unit are respectively connected to mud discharge pipes.

[0055] A method for continuous enhanced water washing and desalination of waste incineration fly ash, specifically using the continuous enhanced water washing and desalination system in this embodiment to treat waste incineration fly ash, comprises the following steps:

[0056] (1) Add waste incineration fly ash and water into the water washing tank 1 of the first water washing unit, open the first valve 11, the hydrodynamic cavitation device 2, the circulating pump 3, the second valve 12, the first mud-water separator 41, the third valve 13, the fourth valve 14, the sixth valve 16 and the second mud-water separator 42, and perform a first-stage circulating elution and a second-stage circulating elution on the slurry in the middle and upper parts of the water washing tank 1 respectively. During the circulating elution process, open the fifth valve 15 and the seventh valve 17 to send the primary water-washed ash produced in the first mud-water separator 41 and the second mud-water separator 42 to the water washing tank 1 of the second water washing unit.

[0057] In step (1), the liquid-to-solid ratio of the slurry in the washing tank 1 is 2.5:1, the residence time of the waste incineration fly ash in the first washing unit is 10 minutes, and the primary washing liquid produced in the second mud-water separator 42 is discharged outward through the eighth valve 18 and the outlet pipe, wherein the conductivity of the primary washing liquid is ≥260mS / cm, and the subsequent treatment of the primary washing liquid includes: recovering sodium salt and potassium salt from the primary washing liquid; the process parameters of the hydraulic cavitation device 2 are: the cavitation number is 0.9; the total circulation flow rate of the material in the first washing unit is 3m / s, wherein the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution process is 5:1.

[0058] (2) Add water to the washing tank 1 of the second washing unit, open the first valve 11, the hydrodynamic cavitation device 2, the circulating pump 3, the second valve 12, the first mud-water separator 41, the third valve 13, the fourth valve 14, the sixth valve 16 and the second mud-water separator 42, and perform a first-stage circulating elution and a second-stage circulating elution on the slurry in the middle and upper parts of the washing tank 1 respectively. During the circulating elution process, open the fifth valve 15 and the seventh valve 17 to send the secondary washed ash produced in the first mud-water separator 41 and the second mud-water separator 42 into the washing tank 1 of the third washing unit.

[0059] In step (2), the liquid-to-solid ratio of the slurry in the washing tank 1 is 2.5:1, the residence time of the primary washed ash in the second washing unit is 8 minutes, and the secondary washing liquid produced in the second mud-water separator 42 is introduced into the washing tank 1 of the first washing unit through the eighth valve 18, wherein the conductivity of the secondary washing liquid is 60 mS / cm; the process parameters of the hydraulic cavitation device 2 are: the cavitation number is 1.2; the total circulation flow rate of the material in the second washing unit is 3 m / s, wherein the flow rate ratio between the first circulation elution and the second circulation elution process is 4:1.

[0060] (3) Add water to the washing tank 1 of the third washing unit, open the first valve 11, the hydrodynamic cavitation device 2, the circulating pump 3, the second valve 12, the first mud-water separator 41, the third valve 13, the fourth valve 14, the sixth valve 16 and the second mud-water separator 42, and perform a first-stage circulating elution and a second-stage circulating elution on the slurry in the middle and upper parts of the washing tank 1 respectively. During the circulating elution process, open the fifth valve 15 and the seventh valve 17 to discharge the tertiary water-washed ash produced in the first mud-water separator 41 and the second mud-water separator 42, thereby completing the treatment of the waste incineration fly ash.

[0061] In step (3), the liquid-to-solid ratio of the slurry in the washing tank 1 is 2.5:1, the residence time of the secondary washing ash in the third washing unit is 4 minutes, and the tertiary washing liquid produced in the second mud-water separator 42 is introduced into the washing tank 1 of the second washing unit through the eighth valve 18, wherein the conductivity of the tertiary washing liquid is 9 mS / cm, and the subsequent treatment of the tertiary washing ash is as follows: the tertiary washing ash is dehydrated to obtain dehydrated ash and filtrate; the moisture content of the dehydrated ash is 30%; the chlorine content in the dehydrated ash is ≤0.5%; the filtrate is used as make-up water and refluxed to each washing tank 1; the process parameters of the hydraulic cavitation device 2 are as follows: the cavitation number is 1.2, the total circulation flow rate of the material in the third washing unit is 2 m / s, and the flow rate ratio between the first circulation elution and the second circulation elution is 2:1.

[0062] Example 2

[0063] A method for continuous enhanced water washing and desalination of waste incineration fly ash, specifically using the continuous enhanced water washing and desalination system in Example 1 to treat the waste incineration fly ash, comprising the following steps:

[0064] S1. Continuously add waste incineration fly ash and water into the water washing tank 1 of the first water washing unit, open the first valve 11, the hydrodynamic cavitation device 2, the circulating pump 3, the second valve 12, the first mud-water separator 41, the third valve 13, the fourth valve 14, the sixth valve 16 and the second mud-water separator 42, and perform a first-stage circulating elution and a second-stage circulating elution on the slurry in the middle and upper parts of the water washing tank 1 respectively. During the circulating elution process, open the fifth valve 15 and the seventh valve 17 to send the primary water-washed ash produced in the first mud-water separator 41 and the second mud-water separator 42 to the water washing tank 1 of the second water washing unit.

[0065] In step S1, the liquid-to-solid ratio of the slurry in the washing tank 1 is 2.5:1; the residence time of the waste incineration fly ash in the first washing unit is 8 minutes; the primary washing liquid produced in the second mud-water separator 42 is discharged outward through the eighth valve 18 and the outlet pipe, wherein the conductivity of the primary washing liquid is ≥260mS / cm, the solid content is 16%, and the subsequent treatment of the primary washing liquid includes: recovering sodium salt and potassium salt from the primary washing liquid; the water content of the primary washing slurry is 70%; the process parameters of the hydraulic cavitation device 2 are: the cavitation number is 0.8; the total circulation flow rate of the material in the first washing unit is 4m / s, and the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution process is 4:1.

[0066] S2. Open the first valve 11, the hydrodynamic cavitator 2, the circulating pump 3, the second valve 12, the first mud-water separator 41, the third valve 13, the fourth valve 14, the sixth valve 16 and the second mud-water separator 42 of the second water washing unit, and perform a first-stage circulating elution and a second-stage circulating elution on the slurry in the middle and upper parts of the water washing tank 1 respectively. During the circulating elution process, open the fifth valve 15 and the seventh valve 17 to feed the secondary water-washed ash produced in the first mud-water separator 41 and the second mud-water separator 42 into the water washing tank 1 of the third water washing unit; open the eighth valve 18 to feed the secondary water washing liquid produced in the first mud-water separator 41 and the second mud-water separator 42 into the water washing tank 1 of the first water washing unit.

[0067] In step S2, the liquid-to-solid ratio of the slurry in the washing tank 1 is 2.5:1; the residence time of the primary washing slurry in the second washing unit is 6 minutes; the secondary washing liquid produced in the second mud-water separator 42 is discharged outward through the eighth valve 18 and the outlet pipe, wherein the conductivity of the secondary washing liquid is 60mS / cm and the solid content is 15%; the water content of the secondary washing slurry is 70%; the process parameters of the hydraulic cavitation device 2 are: the cavitation number is 0.7; the total circulation flow rate of the material in the second washing unit is 4m / s, wherein the flow rate ratio between the first circulation elution and the second circulation elution is 3:1.

[0068] S3. Open the first valve 11, the hydrodynamic cavitation device 2, the circulating pump 3, the second valve 12, the first mud-water separator 41, the third valve 13, the fourth valve 14, the sixth valve 16 and the second mud-water separator 42 of the third water washing unit, and perform a first-stage circulating elution and a second-stage circulating elution on the slurry in the middle and upper parts of the water washing tank 1 respectively. During the circulating elution process, open the eighth valve 18 to send the tertiary water washing liquid produced in the first mud-water separator 41 and the second mud-water separator 42 into the water washing tank 1 of the second water washing unit, and open the fifth valve 15 and the seventh valve 17 to discharge the tertiary water-washed ash produced in the first mud-water separator 41 and the second mud-water separator 42.

[0069] In step S3, the liquid-to-solid ratio of the slurry in the washing tank 1 is 2.0:1; the residence time of the secondary washing slurry in the third washing unit is 4 minutes; the tertiary washing liquid produced in the second mud-water separator 42 is discharged outward through the eighth valve 18 and the outlet pipe, wherein the conductivity of the tertiary washing liquid is 10mS / cm and the solid content is 15%; the water content of the tertiary washing slurry is 70%, and the tertiary washing ash is dehydrated to obtain dehydrated ash and filtrate; the water content of the dehydrated ash is ≤30%, and the chlorine content in the dehydrated ash is ≤0.5%, and the filtrate is used as make-up water and refluxed to each washing tank 1; the process parameters of the hydraulic cavitation device 2 are: the cavitation number is 1.2; the total circulation flow rate of the material in the third washing unit is 3m / s, and the flow rate ratio between the first circulation elution and the second circulation elution is 2:1.

[0070] S4. Repeat steps S1 to S3 to continuously process the waste incineration fly ash.

[0071] The washed ash (three-level washed ash slurry) was tested for leaching toxicity of harmful substances according to the standards of HJ300-2007 (acetic acid leaching), HJ299-2007 (sulfuric acid and nitric acid leaching) and HJ557-2010 (horizontal oscillation leaching), and the results are shown in Table 1. The results show that the test data meet the following requirements: ① the requirements of the pollution control standard for municipal solid waste landfill (GB16889-2008); ② all indicators do not exceed the limit of hazardous waste leaching toxicity (GB5085.3-2007), and it does not belong to hazardous waste with leaching toxicity characteristics; ③ the leaching concentration of each pollutant is lower than the standard limit of the technical specification for pollutant control of municipal solid waste incineration fly ash HJ1134-2020 (GB8978-1996).

[0072] The ash materials before and after washing (three-stage washed ash slurry) were chelated and solidified, and the leaching toxicity test of harmful substances was carried out according to HJ300-2007 (acetic acid leaching). The results are shown in Table 1. The results show that the washed fly ash meets the requirements of the pollution control standard for municipal solid waste landfill (GB16889-2008).

[0073] Table 1 Typical pollutant emission limits and leaching concentrations of fly ash before and after washing and chelation solidification (unit: ppm)

[0074]

[0075] The washed ash (three-level washed ash slurry) was tested for leaching toxicity of harmful substances according to the standards of HJ299-2007 (sulfuric acid and nitric acid leaching) and HJ557-2010 (horizontal oscillation leaching), and the results are shown in Table 2. The results show that the inspection data meet the following requirements: ① All indicators do not exceed the limit of hazardous waste leaching toxicity (GB5085.3-2007), and do not belong to hazardous waste with leaching toxicity characteristics; ② The leaching concentration of each pollutant is lower than the standard limit of HJ1134-2020 (GB8978-1996) of the Technical Specification for Pollutant Control of Fly Ash from Incineration of Municipal Waste.

[0076] Table 2 Typical pollutant emission limits and leaching concentrations of washed fly ash (unit: ppm)

[0077]

[0078]

[0079] The washed ash (three-level washed ash slurry) was analyzed and the residual chlorine content was determined according to the HJ662-2013 standard method, and the results are shown in Table 3. The results show that the residual Cl content in the washed fly ash is ≤0.4%, and the washed fly ash is suitable for cement kiln co-disposal. The fly ash blending ratio in cement production is not limited by the content of various heavy metals contained in the fly ash, which fully meets the requirements of HJ1134-2020 on fly ash cement kiln co-disposal and GB30485-2013 cement kiln co-disposal solid waste pollution control standards.

[0080] Table 3 Heavy metal limits for fly ash used in cement kiln co-treatment and heavy metal content in washed fly ash

[0081]

[0082]

[0083] In Table 3, Note*: includes total chromium in kiln materials and hexavalent chromium in mixed materials; Note**: only mercury in mixed materials is included

[0084] It can be seen from the above results that compared with conventional fly ash washing equipment / methods, the continuous enhanced washing and desalination system for waste incineration fly ash of the present invention has the following advantages: (1) It adopts an external two-stage forced circulation process design to enhance the dissolution and mass transfer of chloride salts, improve the water-ash ratio of each stage of washing and desalination, and consume less water in the overall process; (2) The feeding and discharging of water and ash at each stage, the separation of mud and water at each stage, and the stirring and washing are all continuous, without the need for intermittent operation, thereby improving efficiency; (3) Between the washing units at each stage, an external circulation design is adopted, and the number of process washing stages can be continuously adjusted, resulting in better operating effect and improved stability; (4) There is no need to set up an intermediate temporary storage link, and only a single dehydration process is required at the back end, so the equipment is streamlined, occupies less space, and has lower costs. Therefore, the continuous enhanced water washing and desalination system for waste incineration fly ash of the present invention, through the use of continuous three-stage stirring water washing, two-stage forced circulation enhancement, and two-stage mud-water separation to carry out deep washing and desalination treatment on the fly ash, can efficiently and thoroughly complete the desalination treatment of the fly ash under the premise of effectively reducing the water consumption, has the advantages of simple equipment, easy operation, small footprint, low cost, low water consumption, low energy consumption, high washing efficiency, wide application range, continuous operation and good operation stability, etc., is a new fly ash water washing and desalination system that can be widely used, has high use value, good application prospects, and plays an important role in promoting the reduction and resource utilization of fly ash.

[0085] The above embodiments are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A continuous enhanced water washing and desalination system for waste incineration fly ash, characterized in that: comprising at least 3 water washing units connected in series; The water washing unit comprises a water washing tank (1), a hydraulic cavitation device (2), a circulation pump (3), a first mud-water separator (41) and a second mud-water separator (42); the discharge port of the water washing tank (1) is communicated with the inlet of the hydraulic cavitation device (2) through a first valve (11), and the outlet of the hydraulic cavitation device (2) is communicated with the inlet of the circulation pump (3); the outlet of the circulation pump (3) is communicated with the feed port of the first mud-water separator (41) through a second valve (12); the water outlet of the first mud-water separator (41) is communicated with a first hydraulic cavitation aeration port located in the middle of the water washing tank (1) through a third valve (13); the water outlet of the first mud-water separator (41) is communicated with the feed port of the second mud-water separator (42) through a fourth valve (14); the water outlet of the second mud-water separator (42) is communicated with a second hydraulic cavitation aeration port located in the upper part of the water washing tank (1) through a sixth valve (16); In two adjacent water washing units, the discharge port of the first mud-water separator (41) in the preceding water washing unit is connected to the feed port of the water washing tank (1) in the succeeding water washing unit via a fifth valve (15), and the discharge port of the second mud-water separator (42) in the preceding water washing unit is connected to the feed port of the water washing tank (1) in the succeeding water washing unit via a seventh valve (17); In two adjacent water washing units, the water outlet of the second mud-water separator (42) in the latter water washing unit is connected to the water inlet of the water washing tank (1) in the former water washing unit through the eighth valve (18).

2. The continuous enhanced water washing and desalination system for waste incineration fly ash according to claim 1 is characterized in that: Each of the water washing tanks (1) is also provided with a stirrer (7); the water inlet of each of the water washing tanks (1) is also connected to a water inlet pipe; and the feed inlet of each of the water washing tanks (1) is also connected to a fly ash storage tank.

3. The continuous enhanced water washing and desalination system for waste incineration fly ash according to claim 2 is characterized in that: The first water washing unit further comprises a first material tank (5) and a second material tank (6), wherein the outlets of the first material tank (5) and the second material tank (6) are respectively connected to the feed port of the water washing tank (1); a ninth valve (19) is provided on the pipeline between the first material tank (5) and the water washing tank (1); and a tenth valve (20) is provided on the pipeline between the second material tank (6) and the water washing tank (1).

4. The continuous enhanced water washing and desalination system for waste incineration fly ash according to any one of claims 1 to 3, characterized in that: The first mud-water separator (41) is a cyclone; the second mud-water separator (42) is a cyclone.

5. The continuous enhanced water washing and desalination system for waste incineration fly ash according to any one of claims 1 to 3, characterized in that: The eighth valve (18) of the first water washing unit is also connected to a water outlet pipe; Starting from the third water washing unit, the fifth valve (15) and the seventh valve (17) of the water washing unit are respectively connected with mud discharge pipes.

6. A continuous enhanced water washing and desalination method for waste incineration fly ash, characterized in that: The waste incineration fly ash is treated by using the continuous enhanced water washing and desalination system described in any one of claims 1 to 5.

7. The method for continuous enhanced water washing and desalination of waste incineration fly ash according to claim 6, characterized in that: The following steps are involved: (1) adding fly ash from garbage incineration and water into the water washing tank (1) of the first water washing unit, opening the first valve (11), the hydrodynamic cavitation device (2), the circulating pump (3), the second valve (12), the first mud-water separator (41), the third valve (13), the fourth valve (14), the sixth valve (16) and the second mud-water separator (42), respectively performing a first-stage circulating elution and a second-stage circulating elution on the slurry in the middle and upper parts of the water washing tank (1); during the circulating elution process, opening the fifth valve (15) and the seventh valve (17), and sending the primary water-washed ash produced in the first mud-water separator (41) and the second mud-water separator (42) into the water washing tank (1) of the second water washing unit; (2) adding water to the water washing tank (1) of the second water washing unit, opening the first valve (11), the hydrodynamic cavitation device (2), the circulation pump (3), the second valve (12), the first mud-water separator (41), the third valve (13), the fourth valve (14), the sixth valve (16) and the second mud-water separator (42), respectively performing a first-stage circulation elution and a second-stage circulation elution on the slurry in the middle and upper parts of the water washing tank (1); during the circulation elution process, opening the fifth valve (15) and the seventh valve (17), and sending the secondary water-washed ash produced in the first mud-water separator (41) and the second mud-water separator (42) into the water washing tank (1) of the third water washing unit; (3) Add water to the washing tank (1) of the third washing unit, open the first valve (11), the hydrodynamic cavitation device (2), the circulation pump (3), the second valve (12), the first mud-water separator (41), the third valve (13), the fourth valve (14), the sixth valve (16) and the second mud-water separator (42), and perform a first-stage circulation elution and a second-stage circulation elution on the slurry in the middle and upper parts of the washing tank (1), respectively. During the circulation elution process, open the fifth valve (15) and the seventh valve (17) to discharge the tertiary water-washed ash produced in the first mud-water separator (41) and the second mud-water separator (42), thereby completing the treatment of the waste incineration fly ash.

8. The method for continuous enhanced water washing and desalination of waste incineration fly ash according to claim 7, characterized in that: In step (1), the liquid-to-solid ratio of the slurry in the water washing tank (1) is 2.0 to 2.5:1; the residence time of the waste incineration fly ash in the first water washing unit is 6 minutes to 10 minutes; the primary water washing liquid produced in the second mud-water separator (42) is discharged to the outside through the eighth valve (18) and the outlet pipe; The conductivity of the primary water washing liquid is ≥260mS / cm; the subsequent treatment of the primary water washing liquid includes: recovering sodium salt and potassium salt from the primary water washing liquid; the process parameters of the hydrodynamic cavitation device (2) are: cavitation number is 0.7-1.2, or flow rate control is adopted, the orifice plate diameter is 4mm-6mm, and the flow rate is 5m / s-7m / s; the total circulation flow rate of the material in the first water washing unit is 2m / s-4m / s; the flow rate ratio between the first stage circulation elution and the second stage circulation elution process is 3-5:1; In step (2), the liquid-to-solid ratio of the slurry in the water washing tank (1) is 2.0-2.5:1; the residence time of the primary water-washed ash in the second water washing unit is 6-8 minutes; the secondary water washing liquid produced in the second mud-water separator (42) is introduced into the water washing tank (1) of the first water washing unit through the eighth valve (18); the conductivity of the secondary water washing liquid is 40-60 mS / cm; the process parameters of the hydraulic cavitation device (2) are: the cavitation number is 0.7-1.2, or the flow rate is controlled by the orifice plate diameter of 4-6 mm, and the flow rate is 5-7 m / s; the total circulation flow rate of the material in the second water washing unit is 2-4 m / s; the flow rate ratio between the first circulation elution and the second circulation elution is 3-5:1; In step (3), the liquid-to-solid ratio of the slurry in the water washing tank (1) is 2.0-2.5:1; the residence time of the secondary water-washed ash in the third water washing unit is 4-6 minutes; the tertiary water washing liquid produced in the second mud-water separator (42) is introduced into the water washing tank (1) of the second water washing unit through the eighth valve (18); the conductivity of the tertiary water washing liquid is 5mS / cm-10mS / cm; the subsequent treatment of the tertiary water-washed ash is: dehydrating the tertiary water-washed ash to obtain dehydrated ash and filtrate; the moisture content of the dehydrated ash is 30% to 35%; the chlorine content in the dehydrated ash is ≤0.5%; the filtrate is used as water replenishment and refluxed into the water washing tank (1); the process parameters of the hydraulic cavitation device (2) are: cavitation number is 0.7 to 1.2, or flow rate control is adopted, the orifice plate diameter is 4mm to 6mm, and the flow rate is 5m / s to 7m / s; the total circulation flow rate of the material in the third water washing unit is 2m / s to 4m / s; the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution is 3 to 5:

1.

9. The method for continuous enhanced water washing and desalination of waste incineration fly ash according to claim 6, characterized in that: The following steps are involved: S1. Continuously add waste incineration fly ash and water into the water washing tank (1) of the first water washing unit, open the first valve (11), the hydrodynamic cavitation device (2), the circulation pump (3), the second valve (12), the first mud-water separator (41), the third valve (13), the fourth valve (14), the sixth valve (16) and the second mud-water separator (42), and respectively perform a first-stage circulation elution and a second-stage circulation elution on the slurry in the middle and upper parts of the water washing tank (1). During the circulation elution process, open the fifth valve (15) and the seventh valve (17) to feed the primary water-washed ash produced in the first mud-water separator (41) and the second mud-water separator (42) into the water washing tank (1) of the second water washing unit; S2, opening the first valve (11), the hydrodynamic cavitation device (2), the circulation pump (3), the second valve (12), the first mud-water separator (41), the third valve (13), the fourth valve (14), the sixth valve (16) and the second mud-water separator (42) of the second water washing unit, and performing a first-stage circulation elution and a second-stage circulation elution on the slurry in the middle and upper parts of the water washing tank (1), respectively. During the circulation elution process, opening the fifth valve (15) and the seventh valve (17), and sending the secondary water-washed ash produced in the first mud-water separator (41) and the second mud-water separator (42) into the water washing tank (1) of the third water washing unit; opening the eighth valve (18), and sending the secondary water washing liquid produced in the first mud-water separator (41) and the second mud-water separator (42) into the water washing tank (1) of the first water washing unit; S3, opening the first valve (11), the hydrodynamic cavitation device (2), the circulation pump (3), the second valve (12), the first mud-water separator (41), the third valve (13), the fourth valve (14), the sixth valve (16) and the second mud-water separator (42) of the third water washing unit, and performing a first-stage circulation elution and a second-stage circulation elution on the slurry in the middle and upper parts of the water washing tank (1), respectively. During the circulation elution process, opening the eighth valve (18), and sending the tertiary water washing liquid produced in the first mud-water separator (41) and the second mud-water separator (42) into the water washing tank (1) of the second water washing unit, and opening the fifth valve (15) and the seventh valve (17), and discharging the tertiary water-washed ash produced in the first mud-water separator (41) and the second mud-water separator (42); S4. Repeat steps S1 to S3 to continuously process the waste incineration fly ash.

10. The method for continuous enhanced water washing and desalination of waste incineration fly ash according to claim 9, characterized in that: In step S1, the liquid-to-solid ratio of the slurry in the water washing tank (1) is 2.0-2.5:1; the residence time of the waste incineration fly ash in the first water washing unit is 6-10 minutes; the primary water washing liquid produced in the second mud-water separator (42) is discharged to the outside through the eighth valve (18) and the outlet pipe; The conductivity of the primary water washing liquid is ≥260mS / cm; the subsequent treatment of the primary water washing liquid includes: recovering sodium salt and potassium salt from the primary water washing liquid; the process parameters of the hydrodynamic cavitation device (2) are: cavitation number is 0.7-1.2, or flow rate control is adopted, the orifice plate diameter is 4mm-6mm, and the flow rate is 5m / s-7m / s; the total circulation flow rate of the material in the first water washing unit is 2m / s-4m / s; the flow rate ratio between the first stage circulation elution and the second stage circulation elution process is 3-5:1; In step S2, the liquid-to-solid ratio of the slurry in the water washing tank (1) is 2.0-2.5:1; the residence time of the primary water-washed ash in the second water washing unit is 4-8 minutes; the conductivity of the secondary water washing liquid is 40-60 mS / cm; the process parameters of the hydrodynamic cavitation device (2) are: the cavitation number is 0.7-1.2, or the flow rate is controlled, the orifice plate diameter is 4-6 mm, and the flow rate is 5-7 m / s; the total circulation flow rate of the material in the second water washing unit is 2-4 m / s; the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution is 3-5:1; In step S3, the liquid-to-solid ratio of the slurry in the washing tank (1) is 2.0-2.5:1; the residence time of the secondary washed ash in the third washing unit is 4-6 minutes; the conductivity of the tertiary washing liquid is 5mS / cm-10mS / cm; the subsequent treatment of the tertiary washed ash is: dehydrating the tertiary washed ash to obtain dehydrated ash and filtrate; the moisture content of the dehydrated ash is 30%-35%; the dehydration The chlorine content in the ash is ≤0.5%; the filtrate is used as make-up water and refluxed into the water washing tank (1); the process parameters of the hydraulic cavitation device (2) are: the cavitation number is 0.7-1.2, or flow rate control is adopted, the orifice plate diameter is 4mm-6mm, and the flow rate is 5m / s-7m / s; the total circulation flow rate of the material in the third water washing unit is 2m / s-4m / s; the flow rate ratio between the first-stage circulation elution and the second-stage circulation elution process is 3-5:1.

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