Waste fly ash washing treatment method and system

Abstract

The present invention relates to the technical field of municipal solid waste incineration fly ash treatment, and provides a method and system for washing municipal solid waste incineration fly ash. The method includes evaporating and concentrating the fly ash washing liquid to crystallize and precipitate sodium chloride crystals, and separating to obtain a first mother liquor; obtaining the calcium ion concentration in the first mother liquor, and cooling the first mother liquor to crystallize and precipitate potassium chloride crystals. Wherein, the cooling treatment includes a plurality of cooling stages controlled based on a cooling strategy, and the cooling strategy includes determining temperature parameters of the plurality of cooling stages according to the calcium ion concentration, so that the purity of the potassium chloride crystals reaches a target purity; the temperature parameters include a cooling rate and a stage end temperature. The method and system of the present invention, without relying on external reagents, set a plurality of cooling stages when crystallizing and precipitating potassium chloride, and optimize the temperature parameters of the cooling treatment in stages to inhibit the precipitation of calcium salts, thereby improving the purity of KCl crystals and the process stability.

Description

Technical Field

[0001] The present invention relates to the technical field of waste fly ash treatment, and in particular to a method and system for washing waste fly ash with water. Background Art

[0002] With the acceleration of the urbanization process, the treatment of fly ash generated by waste incineration has become a major challenge in the environmental protection field. Fly ash contains a large amount of chlorides (such as NaCl, KCl, CaCl2) and heavy metals. It is necessary to separate soluble salts through water washing pretreatment to achieve resource utilization. Currently, in the recovery process of fly ash washing liquid, the evaporation crystallization method is widely used to extract sodium chloride (NaCl), and potassium chloride (KCl) in the remaining mother liquor has become the target product for further separation due to its high economic value. However, in actual industrial applications, the purity of potassium chloride crystals is significantly affected by impurity ions (especially calcium ions) in the mother liquor. To solve this problem, existing research has tried to reduce the calcium ion concentration through chemical precipitation methods (such as adding sodium carbonate to remove calcium ions) or ion exchange methods. However, such methods have the following drawbacks: introducing new impurities: chemical agents may remain in the mother liquor, increasing the difficulty of subsequent treatment; high cost: the regeneration of ion exchange resins and the consumption of chemical agents significantly increase the process cost; limited efficiency: the dynamic enrichment characteristics of calcium ions in the evaporation and concentration stage make it difficult to be completely pre-removed. Summary of the Invention

[0003] Therefore, the purpose of the present invention is to solve the problem that calcium ions in the fly ash washing liquid affect the purity of potassium chloride crystals in the existing technology, and to provide a method and system for washing waste fly ash with water. Without relying on external reagents, multiple cooling stages are set when potassium chloride crystallizes, and the temperature parameters of the cooling treatment are optimized in stages to inhibit the precipitation of calcium salts, thereby improving the purity and process stability of KCl crystals.

[0004] In the first aspect, to solve the above technical problems, the present invention provides a method for washing waste fly ash with water, including,

[0005] The fly ash washing liquid enters evaporation and concentration treatment to crystallize and precipitate sodium chloride crystals, and the first mother liquor is separated and obtained;

[0006] The calcium ion concentration in the first mother liquor is obtained, and the first mother liquor is cooled and treated to crystallize and precipitate potassium chloride crystals, and the second mother liquor is separated and obtained;

[0007] The second mother liquor is evaporated and concentrated to obtain a calcium chloride concentrated solution;

[0008] Among them, the cooling treatment includes multiple cooling stages controlled based on a cooling strategy, and the cooling strategy includes determining temperature parameters of the multiple cooling stages according to the calcium ion concentration, so that the purity of the potassium chloride crystal reaches the target purity; the temperature parameters include a cooling rate and a stage end temperature.

[0009] In an embodiment of the present invention, the multiple cooling stages include a first stage that operates at a first cooling rate and a first end temperature; a second stage that operates at a second cooling rate and a second end temperature; a third stage that operates at a third cooling rate and a third end temperature; wherein, the first cooling rate is less than the second cooling rate, and the second cooling rate is less than the third cooling rate.

[0010] In an embodiment of the present invention, the cooling strategy includes obtaining process parameters of the evaporation and concentration treatment and an initial calcium ion concentration in the fly ash washing liquid; predicting a change amount of calcium ions in the evaporation and concentration treatment according to the process parameters and the initial calcium ion concentration; determining an initial temperature parameter of the cooling treatment according to the change amount of calcium ions; correcting the initial temperature parameter according to a monitoring result of the calcium ion concentration in the first mother liquor, and performing the cooling treatment based on the corrected initial temperature parameter.

[0011] In an embodiment of the present invention, determining the initial temperature parameter of the cooling treatment according to the change amount of calcium ions includes predicting an initial calcium ion concentration in the first mother liquor according to the change amount of calcium ions; obtaining a calcium salt-KCl-H2O multi-component phase diagram, and determining a eutectic point temperature T of KCl and the calcium salt at the initial calcium ion concentration; setting a third end temperature T3 according to the eutectic point temperature T.

[0012] In an embodiment of the present invention, setting the third end temperature T3 according to the eutectic point temperature includes: if the initial calcium ion concentration is less than or equal to 0.2%, then setting the third end temperature as: T3 = max(T + 3°C, 5°C); if the initial calcium ion concentration is greater than 0.2%, then setting the third end temperature as: T3 = T + 5°C.

[0013] In an embodiment of the present invention, determining the initial temperature parameter of the cooling treatment according to the change amount of calcium ions includes determining an initial calcium ion concentration in the first mother liquor according to the change amount of calcium ions; obtaining a calcium ion concentration-temperature mapping table, and determining a first end temperature at the initial calcium ion concentration based on the mapping table; determining a second cooling rate and a second end temperature according to the initial calcium ion concentration and the first end temperature; determining a third cooling rate according to the second end temperature and the third end temperature.

[0014] In an embodiment of the present invention, modifying the initial temperature parameter according to the monitoring result of the calcium ion concentration in the first mother liquor includes setting a first reference value for the calcium ion concentration; obtaining the calcium ion concentration in the first mother liquor at the end node of the first stage. If the calcium ion concentration in the first mother liquor at the end node of the first stage is greater than or equal to the first reference value for the calcium ion concentration, then reducing the second cooling rate and lowering the second end temperature; otherwise, performing the cooling in the second stage according to the initial temperature parameter.

[0015] In an embodiment of the present invention, modifying the initial temperature parameter according to the monitoring result of the calcium ion concentration in the first mother liquor further includes setting a second reference value for the calcium ion concentration;

[0016] obtaining the calcium ion concentration in the first mother liquor at the end node of the second stage. If the calcium ion concentration in the first mother liquor at the end node of the second stage is greater than or equal to the second reference value for the calcium ion concentration, then reducing the third cooling rate and increasing the third end temperature T3; otherwise, performing the cooling in the third stage according to the initial temperature parameter.

[0017] In an embodiment of the present invention, predicting the change amount of calcium ions in the evaporation concentration treatment according to the process parameters of the evaporation concentration treatment and the initial calcium ion concentration in the fly ash washing liquid includes obtaining the historical treatment data of the garbage fly ash washing evaporation concentration stage; extracting a set of sample calcium ion concentrations, a set of sample evaporation temperatures, a set of sample evaporation times, a set of sample evaporation pressures, and a set of sample calcium ion change amounts from the historical treatment data; constructing a neural network model, training the neural network model with the set of sample calcium ion concentrations, the set of sample evaporation temperatures, the set of sample evaporation times, and the set of sample evaporation pressures as inputs and the set of sample calcium ion change amounts as outputs to obtain a calcium ion change amount predictor; inputting the process parameters of the evaporation concentration treatment and the initial calcium ion concentration in the fly ash washing liquid into the calcium ion change amount predictor to obtain the calcium ion change amount.

[0018] In a second aspect, based on the same inventive concept, to solve the above technical problems, the present invention further provides a garbage fly ash washing treatment system, including,

[0019] a first evaporation concentration module for evaporating and concentrating the fly ash washing liquid to crystallize out sodium chloride crystals and separating to obtain a first mother liquor;

[0020] a cooling treatment module for cooling the first mother liquor to crystallize out potassium chloride crystals and separating to obtain a second mother liquor; the cooling treatment includes a plurality of cooling stages controlled based on a cooling strategy;

[0021] a second evaporation concentration module for evaporating and concentrating the second mother liquor to obtain a calcium chloride concentrate;

[0022] A calcium ion concentration monitoring module, which is used to monitor the calcium ion concentration throughout the process;

[0023] A feedback control and regulation module, which is used to adjust the temperature parameters of the multiple cooling stages according to the monitored calcium ion concentration, so that the purity of the potassium chloride crystal reaches the target purity; the temperature parameters include the cooling rate and the stage end temperature.

[0024] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0025] The garbage fly ash washing treatment method and system of the present invention set multiple cooling stages when crystallizing potassium chloride without relying on external reagents, and optimize the temperature parameters of the cooling treatment in stages to inhibit the precipitation of calcium salts, thereby improving the purity and process stability of KCl crystals. Description of the Drawings

[0026] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments of the present invention and in combination with the drawings, where

[0027] Figure 1 is a schematic flow chart of the garbage fly ash washing treatment method in the preferred embodiment of the present invention;

[0028] Figure 2 is a schematic flow chart of obtaining the temperature parameters for executing the cooling treatment in the preferred embodiment of the present invention;

[0029] Figure 3 is a structural block diagram of the garbage fly ash washing treatment system in the preferred embodiment of the present invention. Detailed Embodiments

[0030] The following further illustrates the present invention in combination with the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the embodiments cited do not limit the present invention. Embodiment 1

[0031] Referring to Figure 1 as shown, the present invention provides a garbage fly ash washing treatment method, which includes evaporating and concentrating the fly ash washing liquid to crystallize and precipitate sodium chloride crystals, and separating to obtain the first mother liquor; obtaining the calcium ion concentration in the first mother liquor, and cooling the first mother liquor to crystallize and precipitate potassium chloride crystals, and separating to obtain the second mother liquor; evaporating and concentrating the second mother liquor to obtain a calcium chloride concentrate;

[0032] Among them, the cooling treatment includes multiple cooling stages controlled based on a cooling strategy. The cooling strategy includes determining temperature parameters of the multiple cooling stages according to the calcium ion concentration, so that the purity of the potassium chloride crystal reaches the target purity; the temperature parameters include the cooling rate and the stage end temperature.

[0033] In a specific application scenario, the waste fly ash washing liquid is input into a multi-effect evaporator and evaporated and concentrated at 80°C - 100°C until the solution density reaches a certain value (such as 1.2 - 1.3 g / cm³), so that sodium chloride precipitates supersaturated. The sodium chloride crystal is separated by a centrifuge or a filter press device, and the remaining liquid is the first mother liquor; the first mother liquor is subjected to real-time ion chromatography analysis to measure the calcium ion concentration. The first mother liquor is cooled and treated to crystallize potassium chloride crystals. The cooling treatment is divided into multiple cooling stages, and the cooling rate and the stage end temperature of each cooling stage are gradually and dynamically adjusted according to the calcium ion concentration in the first mother liquor to inhibit the co-precipitation of calcium chloride and potassium chloride, and improve the purity of potassium chloride to the target purity. The potassium chloride crystal is separated by vacuum extraction, and the remaining liquid is the second mother liquor. The second mother liquor is input into a thin-film evaporator and concentrated at 120°C - 150°C until the calcium chloride content is ≥40% to obtain a high-concentration calcium chloride solution, which can be directly used as a snow melting agent or industrial raw material, realizing the hierarchical full resource recovery of sodium chloride, potassium chloride, and calcium chloride in waste fly ash.

[0034] In the waste fly ash washing treatment method of the present invention, without relying on external reagents, multiple cooling stages are set when crystallizing potassium chloride, and the temperature parameters of the cooling treatment are optimized in stages to inhibit the precipitation of calcium salts, thereby improving the purity and process stability of the KCl crystal.

[0035] In an embodiment of the present invention, the multiple cooling stages include a first stage that operates at a first cooling rate and a first end temperature; a second stage that operates at a second cooling rate and a second end temperature; a third stage that operates at a third cooling rate and a third end temperature; wherein, the first cooling rate is less than the second cooling rate, and the second cooling rate is less than the third cooling rate.

[0036] In a specific application scenario, the first stage cools slowly, and natural cooling can be selected to cool down, inducing the formation of potassium chloride crystal nuclei, reducing the competitive nucleation of calcium chloride, and improving the purity of potassium chloride crystal nuclei; the third stage cools rapidly, shortening the residence time of the high-calcium mother liquor in the low-temperature area, so that the calcium chloride saturation does not reach the critical value and crystallization is terminated, ultimately improving the purity of potassium chloride. The combination of slow cooling in the first stage and rapid cooling in the later stage shortens the total treatment time and reduces energy consumption.

[0037] One specific implementation process is as follows:

[0038] The first stage of the cooling treatment: The initial temperature of the first mother liquor is slowly cooled from 100 °C to 50 - 55 °C to avoid simultaneous nucleation of calcium chloride and potassium chloride caused by drastic cooling. At the same time, potassium chloride crystal seeds are added to induce the preferential crystallization of potassium chloride, and low-speed stirring (for example, a rotation speed of 30 - 50 rpm) is maintained to promote the uniform growth of crystal nuclei.

[0039] The second stage of the cooling treatment: It is cooled from the end temperature of the first stage to 35 - 40 °C at a medium speed to accelerate the growth of potassium chloride crystals. The stirring rate is dynamically adjusted to 60 - 80 rpm to enhance mass transfer in the solution, prevent crystal aggregation, and the supersaturation of the solution is detected in real time to control the fluctuation of the cooling rate within ±0.2 °C / min.

[0040] The third stage of the cooling treatment: It is rapidly cooled from the end temperature of the second stage to the end temperature to shorten the nucleation time window of calcium chloride. A small amount of sodium polyacrylate can be added as a dispersant to inhibit the attachment of calcium chloride microcrystals to the surface of potassium chloride, and vacuum filtration is used to quickly separate the crystals to reduce the residual mother liquor.

[0041] As one of the embodiments of the present invention, the cooling strategy further includes switching and selecting one of the first stage, the second stage, and the third stage according to the calcium ion concentration as the first treatment stage of the cooling treatment.

[0042] In a specific application scenario, the calcium ion concentration in the first mother liquor is obtained. If the calcium ion concentration is less than 0.3% (i.e., 3 g / Kg), the first stage is selected as the first treatment stage of the cooling treatment to reduce impurity interference; if the calcium ion concentration is greater than or equal to 3 g / Kg and less than or equal to 8 g / Kg, the second stage is selected as the first treatment stage of the cooling treatment to balance crystallization efficiency and purity; if the calcium ion concentration is greater than 0.8% (i.e., 8 g / Kg), the third stage is selected as the first treatment stage of the cooling treatment to avoid the eutectic risk under high calcium concentration. It should be noted that in the implementation scheme of the present invention, the calcium ion concentration is the mass percentage concentration.

[0043] In an embodiment of the present invention, the cooling strategy includes obtaining the process parameters of the evaporation and concentration treatment and the initial calcium ion concentration in the fly ash washing liquid; predicting the change amount of calcium ions in the evaporation and concentration treatment according to the process parameters and the initial calcium ion concentration; determining the initial temperature parameter of the cooling treatment according to the change amount of calcium ions; correcting the initial temperature parameter according to the monitoring result of the calcium ion concentration in the first mother liquor, and performing the cooling treatment based on the corrected initial temperature parameter.

[0044] In specific application scenarios, process parameters in the evaporation and concentration treatment stage are collected, including evaporation temperature, evaporation pressure, and evaporation time, and the initial calcium ion concentration in the fly ash washing liquid is obtained. According to the process parameters in the evaporation and concentration treatment stage and the initial calcium ion concentration, the change amount of calcium ions (i.e., the change amount of calcium ion concentration) during the evaporation and concentration treatment process can be determined, so that the initial calcium ion concentration entering the cooling treatment stage can be determined. Based on the initial calcium ion concentration, the initial temperature parameter for the cooling treatment is determined, and this process forms a first-level correction; then, the initial temperature parameter is corrected according to the detection result of the calcium ion concentration in the first mother liquor, and a closed-loop control is formed through this second-level correction. Finally, the cooling treatment is performed according to the corrected initial temperature parameter. Based on the closed-loop correction, fluctuations in raw materials (such as differences in fly ash batches and changes in evaporation efficiency) can be responded to in real time, reducing the need for manual intervention, and the control accuracy and dynamic adjustment response speed are greatly improved based on the second-level correction.

[0045] In an embodiment of the present invention, determining the initial temperature parameter for the cooling treatment according to the change amount of calcium ions includes predicting the initial calcium ion concentration in the first mother liquor according to the change amount of calcium ions; obtaining a calcium salt-KCl-H2O multi-component phase diagram, and determining the eutectic point temperature T of KCl and the calcium salt at the initial calcium ion concentration; setting a third end temperature T3 according to the eutectic point temperature T; if the initial calcium ion concentration is less than or equal to 0.2% (i.e., 2 g / Kg), then setting the third end temperature as: T3 = max(T + 3°C, 5°C); if the initial calcium ion concentration is greater than 0.2%, then setting the third end temperature as: T3 = T + 5°C.

[0046] In specific application scenarios, after the evaporation and concentration of the fly ash washing liquid, the dynamic change of the calcium ion concentration in the first mother liquor is monitored in real time by an ion chromatograph, the initial concentration before cooling is predicted, and the calcium salt-KCl-H2O multi-component phase diagram is called to determine the eutectic point temperature T of KCl and the calcium salt at the initial calcium ion concentration. For example, at 25°C, the calcium ion concentration is 0.2%, and the eutectic point temperature T of KCl and calcium chloride is 8°C. If the initial calcium ion concentration is less than or equal to 0.2% (i.e., 2 g / Kg), it is a low calcium concentration mode with a low eutectic risk. Appropriately reducing the end temperature can improve the potassium chloride recovery rate, and at the same time, the minimum temperature limit prevents equipment freezing. If the initial calcium ion concentration is greater than 0.2%, it is a high calcium concentration mode. The eutectic region of calcium ions and potassium chloride in the high calcium mother liquor expands, and the third end temperature is significantly increased to T + 5°C to avoid the eutectic window, ensuring the separate precipitation of potassium chloride. By dynamically avoiding the eutectic point, the purity of potassium chloride is improved; in the high calcium mode, the third end temperature increases, and compared with the scheme of forced deep cooling to 5°C, the refrigeration energy consumption is reduced. Based on the temperature offset strategy of the phase diagram, the calcium ion residue amount is greatly reduced, and subsequent ion exchange treatment is not required.

[0047] Specifically, determining the initial temperature parameter of the cooling treatment according to the change amount of calcium ions includes determining the initial calcium ion concentration in the first mother liquor according to the change amount of calcium ions; obtaining a calcium ion concentration-temperature mapping table, and determining a first end temperature at the initial calcium ion concentration based on this mapping table; determining a second cooling rate and a second end temperature according to the initial calcium ion concentration and the first end temperature; and determining a third cooling rate according to the second end temperature and the third end temperature.

[0048] In a specific application scenario, the calcium ion concentration-temperature mapping table is a pre-established mapping table of the initial calcium ion concentration and the first end temperature in the first mother liquor, that is, the initial calcium ion concentration uniquely corresponds to the first end temperature, and the first end temperature is uniquely determined when the initial calcium ion concentration in the first mother liquor is determined. The setting of the first end temperature directly affects the concentration distribution of the remaining salts in the first mother liquor, and further affects the cooling rate and the second end temperature in the second stage. After determining the first end temperature, a second cooling rate and a second end temperature are determined according to the initial calcium ion concentration and the first end temperature. The setting of the second end temperature directly affects the supersaturation and crystallization driving force of KCl in the first mother liquor. If the second end temperature is too low, it may cause KCl to precipitate too quickly in the third stage, forming fine crystals or encapsulating impurities; if the second end temperature is too high, KCl may not be effectively separated, resulting in a decrease in purity. The third cooling rate is determined according to the second end temperature and the third end temperature. Thus, the initial temperature parameter of the cooling treatment is determined according to the change amount of calcium ions. The initial temperature parameters of the three stages are closely linked, and the parameters of each stage directly affect the operating conditions of the subsequent stage, ensuring that the initial temperature parameters of each stage are in the best state, and finally achieving a comprehensive optimization of the purity, yield, energy consumption and crystal quality of potassium chloride crystals.

[0049] Further, correcting the initial temperature parameter according to the monitoring result of the calcium ion concentration in the first mother liquor includes setting a first reference value for the calcium ion concentration; obtaining the calcium ion concentration in the first mother liquor at the end node of the first stage. If the calcium ion concentration in the first mother liquor at the end node of the first stage is greater than or equal to the first reference value of the calcium ion concentration, the second cooling rate is reduced and the second end temperature is lowered; otherwise, the second-stage cooling is performed according to the initial temperature parameter.

[0050] In a specific application scenario, according to the composition characteristics and phase diagram data of the fly ash washing liquid, a first reference value of the calcium ion concentration is set as the basis for judging whether the calcium ion concentration in the first mother liquor is too high after the end of the first stage; if the calcium ion concentration in the first mother liquor at the end node of the first stage is greater than or equal to the first reference value of the calcium ion concentration, it indicates that the calcium ion concentration in the first mother liquor is relatively high at the end of the first stage, which will increase the risk of eutectic of potassium chloride and calcium chloride. At this time, the second cooling rate is reduced to slow down the potassium chloride nucleation rate and avoid crystal wrapping of impurities; and the second end temperature is reduced to further avoid the calcium chloride-potassium chloride eutectic zone. If the calcium ion concentration in the first mother liquor at the end node of the first stage is less than the first reference value of the calcium ion concentration, it indicates that the calcium ion concentration in the first mother liquor is relatively good at the end of the first stage, and there is no need to adjust the cooling parameters in the second stage to avoid frequent adjustment.

[0051] Specifically, modifying the initial temperature parameter according to the monitoring result of the calcium ion concentration in the first mother liquor further includes setting a second reference value of the calcium ion concentration;

[0052] Obtain the calcium ion concentration in the first mother liquor at the end node of the second stage. If the calcium ion concentration in the first mother liquor at the end node of the second stage is greater than or equal to the second reference value of the calcium ion concentration, then reduce the third cooling rate and increase the third end temperature T3; otherwise, perform the third stage cooling according to the initial temperature parameter.

[0053] In a specific application scenario, according to the composition characteristics and phase diagram data of the fly ash washing mother liquor, a second reference value of the calcium ion concentration is set as the basis for judging whether the calcium ion concentration in the mother liquor is too high after the end of the second stage. If the calcium ion concentration in the first mother liquor at the end node of the second stage is greater than or equal to the second reference value of the calcium ion concentration, it indicates that the calcium ion concentration in the first mother liquor is still relatively high at the end of the second stage, which may increase the risk of eutectic of KCl and CaCl2. At this time, the third cooling rate is reduced to slow down the potassium chloride nucleation rate and avoid crystal wrapping of impurities; the third end temperature is increased to further avoid the calcium chloride-potassium chloride eutectic zone. If the calcium ion concentration in the first mother liquor at the end node of the second stage is less than the second reference value of the calcium ion concentration, it indicates that the calcium ion concentration in the first mother liquor is relatively good at the end of the second stage, and there is no need to adjust the cooling parameters in the third stage to avoid frequent adjustment.

[0054] In one embodiment of the present invention, according to the process parameters of the evaporation concentration treatment and the initial calcium ion concentration in the fly ash washing solution, the change amount of calcium ions in the evaporation concentration treatment is predicted, including obtaining historical treatment data in the evaporation concentration stage of fly ash washing; extracting a sample calcium ion concentration set, a sample evaporation temperature set, a sample evaporation time set, a sample evaporation pressure set, and a sample calcium ion concentration change amount set from the historical treatment data; constructing a neural network model, and training the neural network model with the sample calcium ion concentration set, the sample evaporation temperature set, the sample evaporation time set, and the sample evaporation pressure set as inputs and the sample calcium ion concentration change amount set as the output to obtain a calcium ion change amount predictor; inputting the process parameters of the evaporation concentration treatment and the initial calcium ion concentration in the fly ash washing solution into the calcium ion change amount predictor to obtain the calcium ion change amount.

[0055] In a specific application scenario, historical treatment data in the evaporation concentration stage of fly ash washing solution is collected, including calcium ion concentration, the initial calcium ion concentration in the washing solution, and real-time monitoring data during the evaporation concentration process; evaporation temperature, the operating temperature in the evaporator; evaporation time, the time from the start to the end of evaporation; evaporation pressure, the operating pressure in the evaporator; calcium ion concentration change amount, the change value of calcium ion concentration during the evaporation concentration process. A sample set is extracted from the historical data, and a multi-layer perceptron neural network model is constructed, an input layer with four input nodes, corresponding to calcium ion concentration, evaporation temperature, evaporation time, and evaporation pressure respectively, and an output layer with one output node, corresponding to the calcium ion concentration change amount. The historical data is learned and fitted through the neural network model to capture the complex non-linear relationship between multiple process parameters (such as temperature, time, pressure) and the calcium ion concentration change amount during the evaporation concentration process. After training until the convergence condition is reached and the verified calcium ion change amount predictor is put into use, the process parameters of the evaporation concentration treatment and the initial calcium ion concentration in the fly ash washing solution are input into the calcium ion change amount predictor to obtain the calcium ion change amount. Embodiment 2

[0056] Based on the same inventive concept as in Embodiment 1, an embodiment of the present invention provides a fly ash washing treatment system for garbage, as shown in Figure 3 shown, which includes,

[0057] A first evaporation concentration module, which is used to evaporate and concentrate the fly ash washing solution to crystallize out sodium chloride crystals and separate to obtain a first mother liquor;

[0058] A cooling treatment module, which is used to cool the first mother liquor to crystallize out potassium chloride crystals and separate to obtain a second mother liquor; the cooling treatment includes multiple cooling stages controlled based on a cooling strategy;

[0059] A second evaporation and concentration module, which is used to evaporate and concentrate the second mother liquor to obtain a calcium chloride concentrate;

[0060] A calcium ion concentration monitoring module, which is used to monitor the calcium ion concentration throughout the process;

[0061] A feedback control and regulation module, which is used to adjust the temperature parameters of the multiple cooling stages according to the monitored calcium ion concentration, so that the purity of the potassium chloride crystals reaches the target purity; the temperature parameters include the cooling rate and the stage end temperature.

[0062] The waste fly ash washing treatment system of the embodiment of the present invention is used to execute the waste fly ash washing treatment method in Embodiment 1. Based on the same inventive concept, it has the same technical effects and will not be elaborated here.

[0063] In summary, for the waste fly ash washing treatment method and system of the present invention, without relying on external reagents, multiple cooling stages are set when potassium chloride is crystallized, and the temperature parameters of the cooling treatment are optimized in stages to inhibit the precipitation of calcium salts, thereby improving the purity and process stability of KCl crystals.

[0064] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0065] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0066] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions in the process Figure 1one or more processes and / or blocks Figure 1 the functions specified in one or more blocks.

[0067] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one Figure 1 one or more processes and / or blocks Figure 1 or more processes and / or blocks.

[0068] Obviously, the above embodiments are merely examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for washing garbage fly ash, characterized in that: include, The fly ash washing liquid enters into evaporation and concentration treatment to crystallize sodium chloride crystals, and separates to obtain the first mother liquor; Obtaining the calcium ion concentration in the first mother liquor, cooling the first mother liquor to crystallize potassium chloride crystals, and separating to obtain a second mother liquor; Concentrating the second mother liquor by evaporation to obtain a calcium chloride concentrate; The cooling process includes a plurality of cooling stages controlled based on a cooling strategy, wherein the cooling strategy includes determining temperature parameters of the plurality of cooling stages according to the calcium ion concentration so that the purity of the potassium chloride crystals reaches a target purity; the temperature parameters include a cooling rate and a stage end temperature; The multiple cooling stages include a first stage, which is operated at a first cooling rate and a first end temperature; a second stage, which is operated at a second cooling rate and a second end temperature; The third stage is operated at a third cooling rate and a third terminal temperature; The cooling strategy includes: Obtaining the process parameters of the evaporation concentration treatment and the initial calcium ion concentration in the fly ash water wash; Predicting the change in calcium ion amount during the evaporation and concentration process according to the process parameters and the initial calcium ion concentration; Determining the initial temperature parameter of the cooling treatment according to the change in the calcium ion amount: including predicting the initial concentration of calcium ions in the first mother liquor according to the change in the calcium ion amount; Obtaining a calcium salt-KCl-H2O multi-element phase diagram, and determining the eutectic point temperature T of KCl and the calcium salt at the initial concentration of calcium ions; The third endpoint temperature T3 is set according to the eutectic point temperature T; if the initial calcium ion concentration is less than or equal to 0.2%, the third endpoint temperature is set to: T3=max(T+3°C, 5°C); if the initial calcium ion concentration is greater than 0.2%, the third endpoint temperature is set to: T3=T+5°C.

2. The method for washing garbage fly ash according to claim 1, characterized in that: It also includes correcting the initial temperature parameters according to the monitoring results of the calcium ion concentration in the first mother liquor, and performing cooling treatment based on the corrected initial temperature parameters; wherein the first cooling rate is less than the second cooling rate, and the second cooling rate is less than the third cooling rate.

3. The method for washing garbage fly ash according to claim 2, characterized in that: The cooling strategy also includes switching and selecting one of the first stage, the second stage and the third stage as the first treatment stage of the cooling treatment according to the calcium ion concentration.

4. The method for washing garbage fly ash according to claim 1, characterized in that: Determining the initial temperature parameter of the cooling treatment according to the change in the calcium ion amount includes: Determining the initial concentration of calcium ions in the first mother solution according to the change in the amount of calcium ions; Obtaining a calcium ion concentration-temperature mapping table, and determining a first endpoint temperature at the initial calcium ion concentration based on the mapping table; Determining a second cooling rate and a second endpoint temperature according to the initial calcium ion concentration and the first endpoint temperature; A third cooling rate is determined according to the second endpoint temperature and the third endpoint temperature.

5. The method for washing garbage fly ash according to claim 1, characterized in that: Correcting the initial temperature parameter according to the monitoring result of the calcium ion concentration in the first mother liquor includes: Setting a first reference value of calcium ion concentration; The calcium ion concentration in the first mother liquor at the end node of the first stage is obtained. If the calcium ion concentration in the first mother liquor at the end node of the first stage is greater than or equal to the first reference value of the calcium ion concentration, the second cooling rate is reduced and the second terminal temperature is lowered; otherwise, the second stage cooling is performed according to the initial temperature parameters.

6. The method for washing garbage fly ash according to claim 5, characterized in that: The initial temperature parameter is corrected according to the monitoring result of the calcium ion concentration in the first mother liquor, and further includes: Setting a second reference value of calcium ion concentration; The calcium ion concentration in the first mother liquor at the end node of the second stage is obtained. If the calcium ion concentration in the first mother liquor at the end node of the second stage is greater than or equal to the second reference value of the calcium ion concentration, the third cooling rate is reduced and the third end point T3 temperature is increased; otherwise, the third stage cooling is performed according to the initial temperature parameters.

7. The method for washing garbage fly ash according to claim 1, characterized in that: According to the process parameters of the evaporation concentration treatment and the initial calcium ion concentration in the fly ash water wash, the change amount of calcium ions in the evaporation concentration treatment is predicted. include, Obtain historical processing data of the waste fly ash washing, evaporation and concentration stage; Extracting a sample calcium ion concentration set, a sample evaporation temperature set, a sample evaporation time set, a sample evaporation pressure set, and a sample calcium ion concentration variation set from the historical processing data; Constructing a neural network model, taking a sample calcium ion concentration set, a sample evaporation temperature set, a sample evaporation time set, and a sample evaporation pressure set as input, and taking the sample calcium ion concentration change amount set as output to train the neural network model to obtain a calcium ion change amount predictor; The process parameters of the evaporation concentration treatment and the initial calcium ion concentration in the fly ash water wash liquid are input into the calcium ion change amount predictor to obtain the calcium ion change amount.

8. A garbage fly ash washing treatment system, characterized by: include, A first evaporation and concentration module is used to evaporate and concentrate the fly ash water washing liquid to crystallize sodium chloride crystals and separate to obtain a first mother liquor; A cooling treatment module, which is used to cool the first mother liquor to crystallize potassium chloride crystals and separate to obtain a second mother liquor; the cooling treatment includes multiple cooling stages controlled based on a cooling strategy; the multiple cooling stages include a first stage, which operates at a first cooling rate and a first end temperature; a second stage, which operates at a second cooling rate and a second end temperature; and a third stage, which operates at a third cooling rate and a third end temperature; A second evaporation and concentration module, which is used to evaporate and concentrate the second mother liquor to obtain a calcium chloride concentrate; Calcium ion concentration monitoring module, which is used to monitor calcium ion concentration throughout the entire process; A feedback control and regulation module, which is used to adjust the temperature parameters of the multiple cooling stages according to the monitored calcium ion concentration so that the purity of the potassium chloride crystals reaches the target purity; the temperature parameters include the cooling rate and the stage end temperature; The cooling strategy includes: Obtaining the process parameters of the evaporation concentration and the initial calcium ion concentration in the fly ash water wash; Predicting the change in calcium ion amount during the evaporation and concentration process according to the process parameters and the initial calcium ion concentration; Determining the initial temperature parameter of the cooling treatment according to the change in the calcium ion amount: including predicting the initial concentration of calcium ions in the first mother liquor according to the change in the calcium ion amount; Obtaining a calcium salt-KCl-H2O multi-element phase diagram, and determining the eutectic point temperature T of KCl and the calcium salt at the initial concentration of calcium ions; The third endpoint temperature T3 is set according to the eutectic point temperature T; if the initial calcium ion concentration is less than or equal to 0.2%, the third endpoint temperature is set to: T3=max(T+3°C, 5°C); if the initial calcium ion concentration is greater than 0.2%, the third endpoint temperature is set to: T3=T+5°C.

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