Garbage fly ash washing treatment method and system

Abstract

The invention relates to the technical field of garbage fly ash treatment, and provides a garbage fly ash water washing treatment method and system.The method comprises the steps that fly ash water washing liquid is subjected to evaporation and concentration treatment, sodium chloride crystals are separated out through crystallization, and first mother liquor is obtained through separation; obtaining the concentration of calcium ions in the first mother liquor, and cooling the first mother liquor to crystallize and separate out potassium chloride crystals; wherein the cooling treatment comprises a plurality of cooling stages controlled based on a cooling strategy, and the cooling strategy comprises the step of determining temperature parameters of the plurality of cooling stages according to the calcium ion concentration, so that the purity of the potassium chloride crystal reaches the target purity; the temperature parameters comprise a cooling rate and a stage end point temperature. According to the method and the system, a plurality of cooling stages are set when potassium chloride is crystallized and separated out under the condition of not depending on additional reagents, and temperature parameters of cooling treatment are optimized in stages to inhibit calcium salt separation, so that the purity and the process stability of KCl crystals are improved.

Description

Technical Field

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

[0002] With the acceleration of urbanization, the treatment of fly ash produced by garbage incineration has become a major challenge in the field of environmental protection. Fly ash contains a large amount of chloride salts (such as NaCl, KCl, CaCl2) and heavy metals. Soluble salts need to be separated by water washing pretreatment to achieve resource utilization. At present, in the recovery process of fly ash water washing liquid, evaporation crystallization 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. In order to solve this problem, some studies have tried to reduce the calcium ion concentration by chemical precipitation (such as adding sodium carbonate to remove calcium ions) or ion exchange, but such methods have the following disadvantages: introduction of new impurities: chemical agents may remain in the mother liquor, increasing the difficulty of subsequent treatment; high cost: ion exchange resin regeneration and agent consumption 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] To this end, the purpose of the present invention is to solve the problem that calcium ions in fly ash washing liquid affect the purity of potassium chloride crystals in the prior art, and to provide a method and system for washing garbage fly ash. Under the condition of not 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 of KCl crystals and process stability.

[0004] In the first aspect, in order to solve the above technical problems, the present invention provides a method for washing garbage fly ash, comprising: 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 treatment includes a plurality of cooling stages controlled based on a cooling strategy, wherein the cooling strategy includes determining the temperature parameters of the plurality of cooling stages according to the 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.

[0005] In one embodiment of the present invention, the multiple cooling stages include a first stage, which operates at a first cooling rate and a first terminal temperature; a second stage, which operates at a second cooling rate and a second terminal temperature; and a third stage, which operates at a third cooling rate and a third terminal 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.

[0006] In one 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 water wash liquid; predicting the calcium ion change of the evaporation and concentration treatment according to the process parameters and the initial calcium ion concentration; determining the initial temperature parameters of the cooling treatment according to the calcium ion change; correcting the initial temperature parameters according to the monitoring results of the calcium ion concentration in the first mother liquor, and performing the cooling treatment based on the corrected initial temperature parameters.

[0007] In one embodiment of the present invention, the initial temperature parameters of the cooling treatment are determined 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 multivariate phase diagram to determine the eutectic point temperature T of KCl and calcium salt at the initial calcium ion concentration; and setting a third endpoint temperature T3 according to the eutectic point temperature T.

[0008] In one embodiment of the present invention, the third endpoint temperature T3 is set according to the eutectic point temperature, including if the initial calcium ion concentration is less than or equal to 0.2%, setting the third endpoint temperature to: T3=max(T+3°C, 5°C); if the initial calcium ion concentration is greater than 0.2%, setting the third endpoint temperature to: T3=T+5°C.

[0009] In one embodiment of the present invention, the initial temperature parameters of the cooling treatment are determined according to the change in the calcium ions, including determining the initial concentration of calcium ions in the first mother liquor according to the change in the calcium ions; obtaining a calcium ion concentration-temperature mapping table, and determining the first endpoint temperature at the initial calcium ion concentration based on the mapping table; determining the second cooling rate and the second endpoint temperature according to the initial calcium ion concentration and the first endpoint temperature; and determining the third cooling rate according to the second endpoint temperature and the third endpoint temperature.

[0010] In one embodiment of the present invention, the initial temperature parameters are corrected according to the monitoring results of the calcium ion concentration in the first mother liquor, including setting a first reference value of 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 of 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, then reducing the second cooling rate and lowering the second terminal temperature; otherwise, performing the second stage cooling according to the initial temperature parameters.

[0011] In one embodiment of the present invention, 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 the 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.

[0012] In one embodiment of the present invention, the change amount of calcium ions in the evaporation and concentration treatment is predicted according to the process parameters of the evaporation and concentration treatment and the initial calcium ion concentration in the fly ash water washing liquid, including obtaining historical processing data of the evaporation and concentration stage of garbage fly ash water 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 processing data; constructing a neural network model, taking 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 taking the sample calcium ion concentration change amount set as outputs to train the neural network model to obtain a calcium ion change amount predictor; inputting the process parameters of the evaporation and concentration treatment and the initial calcium ion concentration in the fly ash water washing liquid into the calcium ion change amount predictor to obtain the calcium ion change amount.

[0013] In the second aspect, based on the same inventive concept, in order to solve the above technical problems, the present invention also provides a garbage fly ash washing treatment system, comprising: 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; 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 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.

[0014] The above technical solution of the present invention has the following beneficial effects compared with the prior art: The method and system for washing waste fly ash of the present invention provide 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 It is a schematic flow chart of a method for washing garbage fly ash in a preferred embodiment of the present invention; Figure 2 A schematic diagram of a flow chart for obtaining temperature parameters for executing a cooling process in a preferred embodiment of the present invention; Figure 3 It is a structural block diagram of the garbage fly ash washing treatment system in the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Embodiment 1

[0017] Reference Figure 1 As shown, the present invention provides a method for washing garbage fly ash, comprising: subjecting the fly ash washing liquid to evaporation and concentration treatment 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, and separating to obtain a second mother liquor; evaporating and concentrating the second mother liquor to obtain a calcium chloride concentrate; The cooling treatment includes a plurality of cooling stages controlled based on a cooling strategy, wherein the cooling strategy includes determining the temperature parameters of the plurality of cooling stages according to the 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.

[0018] In the specific application scenario, the garbage fly ash washing liquid is input into the multi-effect evaporator, evaporated and concentrated at 80℃-100℃ until the solution density reaches a certain value (such as 1.2-1.3 g / cm³), so that sodium chloride is supersaturated and precipitated, and sodium chloride crystals are separated by a centrifuge or a filter press. The remaining liquid is the first mother liquor; the first mother liquor is subjected to real-time ion chromatography analysis to determine the calcium ion concentration. The first mother liquor is cooled to crystallize potassium chloride crystals, and the cooling treatment is divided into multiple cooling stages. The cooling rate and the 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 precipitation of calcium chloride and potassium chloride eutectics and increase the purity of potassium chloride to the target purity. Potassium chloride crystals are 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 to a calcium chloride content of ≥40% at 120℃-150℃ to obtain a high-concentration calcium chloride solution, which can be directly used as a snow melting agent or industrial raw material, thereby realizing the graded and full resource recovery of sodium chloride, potassium chloride and calcium chloride in garbage fly ash.

[0019] The waste fly ash washing treatment method of the present invention sets multiple cooling stages when crystallizing potassium chloride without relying on external reagents, and optimizes the temperature parameters of the cooling treatment in stages to inhibit the precipitation of calcium salts, thereby improving the purity of KCl crystals and process stability.

[0020] In one embodiment of the present invention, the multiple cooling stages include a first stage, which operates at a first cooling rate and a first terminal temperature; a second stage, which operates at a second cooling rate and a second terminal temperature; and a third stage, which operates at a third cooling rate and a third terminal 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.

[0021] In specific application scenarios, the first stage is slow cooling, and natural cooling can be selected to induce the formation of potassium chloride crystal nuclei, reduce the competitive nucleation of calcium chloride, and improve the purity of potassium chloride crystal nuclei; the third stage is rapid cooling, which shortens the residence time of high-calcium mother liquor in the low temperature zone, so that the crystallization is terminated before the calcium chloride saturation reaches the critical value, and finally improves the purity of potassium chloride. The combination of slow cooling in the first stage and rapid cooling in the later stage shortens the total processing time and reduces energy consumption.

[0022] One of the specific implementation processes is as follows: The first stage of cooling treatment: the initial temperature of the first mother liquor is slowly cooled from 100°C to 50-55°C to avoid drastic cooling that may cause simultaneous nucleation of calcium chloride and potassium chloride. At the same time, potassium chloride seed crystals are added to induce potassium chloride to crystallize preferentially, and low-speed stirring (e.g., 30-50rpm) is maintained to promote uniform growth of crystal nuclei.

[0023] The second stage of cooling treatment: cooling from the terminal temperature of the first stage to 35-40°C at a medium speed to accelerate the growth of potassium chloride crystals, dynamically adjust the stirring rate to 60-80rpm, enhance the mass transfer of the solution, prevent crystal aggregation, and detect the supersaturation of the solution in real time to control the fluctuation of the cooling rate within ±0.2°C / min.

[0024] The third stage of cooling treatment: Rapidly cool down from the endpoint temperature of the second stage to the endpoint temperature to shorten the nucleation time window of calcium chloride. A trace amount of sodium polyacrylate can be added as a dispersant to inhibit the adhesion of calcium chloride microcrystals to the surface of potassium chloride. Vacuum filtration is used to quickly separate the crystals to reduce the residual mother liquor.

[0025] As one of the embodiments of the present invention, the cooling strategy also includes switching and selecting one of the first stage, the second stage and the third stage as the first processing stage of the cooling treatment according to the calcium ion concentration.

[0026] 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., 3g / 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 3g / Kg and less than or equal to 8g / Kg, the second stage is selected as the first treatment stage of the cooling treatment to balance the crystallization efficiency and purity; if the calcium ion concentration is greater than 0.8% (i.e., 8g / Kg), the third stage is selected as the first treatment stage of the cooling treatment to avoid the risk of eutectic under high calcium concentration. It should be noted that in the embodiments of the present invention, the calcium ion concentration is the mass percentage concentration.

[0027] In one 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 water wash liquid; predicting the calcium ion change of 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 calcium ion change; 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.

[0028] In specific application scenarios, the process parameters of 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 water washing liquid is obtained. According to the process parameters and initial calcium ion concentration of the evaporation and concentration treatment stage, the change of calcium ions in the evaporation and concentration treatment process (i.e., the change of calcium ion concentration) can be determined, so that the initial concentration of calcium ions entering the cooling treatment stage can be determined. The initial temperature parameters of the cooling treatment are determined according to the initial calcium ion concentration. This process forms a first-level correction; then the initial temperature parameters are corrected according to the detection results of the calcium ion concentration in the first mother liquor. The second-level correction of this process forms a closed-loop control, and finally the cooling treatment is performed according to the corrected initial temperature parameters. Based on the closed-loop correction, it is possible to respond to raw material fluctuations (such as fly ash batch differences, evaporation efficiency changes) in real time, reduce the need for manual intervention, and greatly improve the control accuracy and dynamic adjustment response speed based on the second-level correction.

[0029] In one embodiment of the present invention, the initial temperature parameters of the cooling treatment are determined 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-component phase diagram to determine the eutectic point temperature T of KCl and calcium salt at the initial calcium ion concentration; setting a third endpoint 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., 2g / Kg), setting the third endpoint temperature to: T3=max(T+3°C, 5°C); if the initial calcium ion concentration is greater than 0.2%, setting the third endpoint temperature to: T3=T+5°C.

[0030] In specific application scenarios, after the fly ash water washing liquid is evaporated and concentrated, the dynamic changes of the calcium ion concentration in the first mother liquor are monitored in real time by an ion chromatograph, the initial concentration before cooling is predicted, and the calcium salt-KCl-H2O multivariate phase diagram is called to determine the eutectic point temperature T of KCl and 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., 2g / Kg), it is a low calcium concentration mode with low eutectic risk. A moderate reduction in the endpoint temperature can increase the potassium chloride yield, and the minimum temperature limit prevents the equipment from freezing. If the initial calcium ion concentration is greater than 0.2%, it is a high calcium concentration mode. The calcium ions in the high calcium mother liquor expand in the potassium chloride eutectic zone, significantly increasing the third endpoint temperature to T+5°C to avoid the eutectic window and ensure that potassium chloride is precipitated alone. The purity of potassium chloride is improved by dynamically avoiding the eutectic point; the third endpoint temperature is increased in the high calcium mode, and the refrigeration energy consumption is reduced compared with the solution of forced deep cooling to 5°C. The temperature shift strategy based on the phase diagram greatly reduces the residual calcium ions and eliminates the need for subsequent ion exchange treatment.

[0031] Specifically, determining the initial temperature parameters of the cooling treatment according to the calcium ion change includes: determining the initial calcium ion concentration in the first mother liquor according to the calcium ion change; obtaining a calcium ion concentration-temperature mapping table, and determining the first endpoint temperature at the initial calcium ion concentration based on the mapping table; determining the second cooling rate and the second endpoint temperature according to the initial calcium ion concentration and the first endpoint temperature; and determining the third cooling rate according to the second endpoint temperature and the third endpoint temperature.

[0032] In a specific application scenario, the calcium ion concentration-temperature mapping table is a pre-established mapping table of the initial calcium ion concentration in the first mother liquor and the first endpoint temperature, that is, the initial calcium ion concentration uniquely corresponds to the first endpoint temperature, and the first endpoint temperature is uniquely determined when the initial calcium ion concentration in the first mother liquor is determined. The setting of the first endpoint temperature directly affects the concentration distribution of the remaining salts in the first mother liquor, and then affects the cooling rate and the second endpoint temperature in the second stage. After determining the first endpoint temperature, the second cooling rate and the second endpoint temperature are determined according to the initial calcium ion concentration and the first endpoint temperature. The setting of the second endpoint temperature directly affects the supersaturation and crystallization driving force of KCl in the first mother liquor. If the second endpoint temperature is too low, KCl may precipitate too quickly in the third stage, forming fine crystals or encapsulating impurities; if the second endpoint temperature is too high, KCl may not be effectively separated, resulting in a decrease in purity. Determine the third cooling rate based on the second endpoint temperature and the third endpoint temperature. Therefore, the initial temperature parameters of the cooling treatment are determined according to the change in the calcium ion amount. 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 stages, ensuring that the initial temperature parameters of each stage are in the best state, and ultimately achieving comprehensive optimization of the purity, yield, energy consumption and crystal quality of potassium chloride crystals.

[0033] Furthermore, the initial temperature parameters are corrected according to the monitoring results of the calcium ion concentration in the first mother liquor, including setting a first reference value of 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 of 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, then reducing the second cooling rate and lowering the second terminal temperature; otherwise, performing the second stage cooling according to the initial temperature parameters.

[0034] In specific application scenarios, according to the composition characteristics and phase diagram data of the fly ash water wash liquid, the first reference value of 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 calcium ion concentration, it means 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 potassium chloride and calcium chloride eutectics. At this time, the second cooling rate is reduced to slow down the nucleation rate of potassium chloride and avoid crystals encapsulating impurities; and the second terminal temperature is lowered to further avoid the calcium chloride-potassium chloride eutectic region. 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 calcium ion concentration, it means that the calcium ion concentration in the first mother liquor is better at the end of the first stage, and there is no need to adjust the cooling parameters of the second stage to avoid frequent adjustments.

[0035] Specifically, the initial temperature parameter is corrected according to the monitoring result of the calcium ion concentration in the first mother liquor, and also includes setting a second reference value of the 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.

[0036] In specific application scenarios, according to the composition characteristics and phase diagram data of the fly ash washing mother liquor, the second reference value of 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 of the first mother liquor at the end node of the second stage is greater than or equal to the second reference value of calcium ion concentration, it means that the calcium ion concentration in the first mother liquor is still 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 nucleation rate of potassium chloride and avoid crystals encapsulating impurities; the third terminal temperature is increased to further avoid the calcium chloride-potassium chloride eutectic region. If the calcium ion concentration of the first mother liquor at the end node of the second stage is less than the second reference value of calcium ion concentration, it means that the calcium ion concentration in the first mother liquor at the end of the second stage is better, and there is no need to adjust the cooling parameters of the third stage to avoid frequent adjustments.

[0037] In one embodiment of the present invention, the change amount of calcium ions in the evaporation and concentration treatment is predicted according to the process parameters of the evaporation and concentration treatment and the initial calcium ion concentration in the fly ash water washing liquid, including obtaining historical processing data of the evaporation and concentration stage of garbage fly ash water 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 processing data; constructing a neural network model, taking 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 taking the sample calcium ion concentration change amount set as outputs to train the neural network model to obtain a calcium ion change amount predictor; inputting the process parameters of the evaporation and concentration treatment and the initial calcium ion concentration in the fly ash water washing liquid into the calcium ion change amount predictor to obtain the calcium ion change amount.

[0038] In the specific application scenario, the historical processing data of the evaporation and concentration stage of the garbage fly ash washing liquid is collected, including calcium ion concentration, initial calcium ion concentration in the washing liquid and real-time monitoring data during the evaporation and 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, the change value of calcium ion concentration during evaporation and concentration. Extract a sample set from the historical data, and construct a multi-layer perceptron neural network model with an input layer of four input nodes, corresponding to calcium ion concentration, evaporation temperature, evaporation time and evaporation pressure, and an output layer of one output node, corresponding to the calcium ion concentration change. The historical data is learned and fitted by the neural network model to capture the complex nonlinear relationship between multiple process parameters (such as temperature, time, and pressure) and the calcium ion concentration change during the evaporation and concentration process. The training is carried out until the convergence condition is reached, and the qualified calcium ion change predictor is put into use. The process parameters of the evaporation and concentration treatment and the initial calcium ion concentration in the fly ash washing liquid are input into the calcium ion change predictor to obtain the calcium ion change. Embodiment 2

[0039] Based on the same inventive concept as that of the first embodiment, the present invention provides a garbage fly ash washing treatment system, referring to Figure 3 As shown, it includes, 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; 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 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.

[0040] The garbage fly ash water washing treatment system of the embodiment of the present invention is used to execute the garbage fly ash water washing treatment method in the first embodiment. It is based on the same inventive concept and has the same technical effect, and will not be described in detail here.

[0041] In summary, the method and system for washing fly ash 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 of KCl crystals and process stability.

[0042] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt 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 codes.

[0043] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0044] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0045] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0046] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled 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 list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the 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 treatment includes a plurality of cooling stages controlled based on a cooling strategy, wherein the cooling strategy includes determining the temperature parameters of the plurality of cooling stages according to the 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.

2. The method for washing garbage fly ash according to claim 1, characterized in that: The multiple cooling stages include: The first stage is operated at a first cooling rate and a first terminal temperature; The second stage is operated at a second cooling rate and a second terminal temperature; The third stage is operated at a third cooling rate and a third terminal temperature; The first cooling rate is smaller than the second cooling rate, and the second cooling rate is smaller 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 or 2, characterized in that: 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 an initial temperature parameter of the cooling treatment according to the change in the calcium ion amount; The initial temperature parameter is corrected according to the monitoring result of the calcium ion concentration in the first mother liquor, and the temperature reduction process is performed based on the corrected initial temperature parameter.

5. The method for washing garbage fly ash according to claim 4, characterized in that: Determining the initial temperature parameter of the cooling treatment according to the change in the calcium ion amount includes: Predicting the initial concentration of calcium ions in the first mother solution according to the change in the amount of calcium ions; 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; Setting a third endpoint temperature T3 according to the eutectic point temperature T; Wherein, if the initial calcium ion concentration is less than or equal to 0.2%, the third end point temperature is set to: T3=max(T+3°C, 5°C); If the initial calcium ion concentration is greater than 0.2%, the third end point temperature is set to: T3=T+5°C.

6. The method for washing garbage fly ash according to claim 4, 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.

7. The method for washing garbage fly ash according to claim 4, 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.

8. The method for washing garbage fly ash according to claim 4, 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.

9. The method for washing garbage fly ash according to claim 4, 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.

10. A garbage fly ash washing treatment system, characterized in that: 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 based on cooling strategy control; 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 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.

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