Equipment and Method for Efficient Removal of Chloride Salts in Municipal Solid Waste Incineration Fly Ash by Hydrodynamic Cavitation

Abstract

The present invention discloses an apparatus and method for efficiently removing chlorides from municipal solid waste incineration fly ash through hydrodynamic cavitation. The apparatus includes a fly ash silo, a stirring tank, a peristaltic pump, two cavitation tubes, a water storage tank, a filter press, and a wastewater recycling component. The method comprises the following steps: S1, preparation of fly ash slurry; S2, fitting of hydrodynamic cavitation parameters; S3, staged hydrodynamic cavitation: S3-1, determination of the optimal mass concentration; S3-2, determination of the optimal cavitation flow velocity; S4, continuous hydrodynamic cavitation; S5, post-treatment. Through hydrodynamic cavitation, the present invention can effectively promote the dissolution of soluble chlorides, greatly improve the removal rate of soluble chlorides, further reduce industrial water consumption, and the recycled water can be recycled, with low cost and good chloride removal effect. No chemical agents are used in the process of fly ash dechlorination, and environmental protection and efficient impurity removal of incineration fly ash can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of harmless treatment of incineration fly ash, and specifically relates to an apparatus and method for efficiently removing chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation. Background Art

[0002] A large amount of incineration fly ash is generated during the process of municipal solid waste incineration. Fly ash has certain resource potential, such as being used to prepare cement and lightweight aggregates, as subgrade landfill materials, and to prepare ceramics and glass. However, due to the volatilization and enrichment of a large amount of chlorine-containing substances in fly ash particles, it needs to be safely treated before it can be landfilled or resourcefully utilized in a municipal solid waste landfill. Therefore, how to effectively remove chlorine from fly ash is crucial for improving its comprehensive utilization rate.

[0003] The existing treatment methods for chlorine-containing substances in fly ash mainly rely on multi-stage water washing, which has disadvantages such as large water consumption and poor removal effect. Compared with other pretreatment processes, hydrodynamic cavitation can provide an extremely strong slurry flow field environment, thereby effectively promoting the dissolution of soluble chlorides and significantly reducing industrial water consumption. Therefore, using hydrodynamic cavitation to efficiently remove soluble chlorides is of great significance for improving the comprehensive utilization of fly ash.

[0004] However, the current process of applying hydrodynamic cavitation to the treatment of chlorine-containing substances in fly ash is not yet perfect, and various process parameters need to be optimized. At the same time, targeted treatment is also required for different types of fly ash.

[0005] For example, Patent CN117900244A discloses a method for synergistically treating municipal solid waste incineration fly ash by hydrodynamic cavitation and carbonation, including the following steps: pulping and washing the fly ash, introducing carbon dioxide-containing gas for carbonation washing, performing solid-liquid separation to obtain a first solid phase and a first clear liquid; evaporating and crystallizing the first clear liquid, collecting the condensed water, mixing it with the first solid phase, performing hydrodynamic cavitation washing on the obtained mixed liquid, and performing solid-liquid separation to obtain a second clear liquid, which is recycled to the water washing process of fly ash to complete the treatment. It can achieve efficient elution of chlorides in fly ash, simultaneously degrade dioxin-like substances in fly ash, and reduce the water volume required for fly ash washing. It has advantages such as low treatment cost, high treatment efficiency, good treatment effect, and both environmental and economic benefits, as well as being efficient, environmentally friendly, and simple to operate. However, the method does not involve the adjustment of specific treatment process parameters for different types of fly ash, and the method is relatively general. Summary of the Invention

[0006] In view of the above problems, the present invention provides an apparatus and method for efficiently removing chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation.

[0007] The technical solution of the present invention is as follows:

[0008] Equipment for efficiently removing chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation, comprising a fly ash silo, a stirring tank, a peristaltic pump, two cavitation tubes, a water storage tank, a filter press and a wastewater reuse assembly. The discharge pipe of the fly ash silo is connected to the inlet of the stirring tank. The discharge opening of the stirring tank is connected to the peristaltic pump. The peristaltic pump is connected to the two cavitation tubes respectively through a three-way valve. The water storage tank is connected to the stirring tank and the two cavitation tubes respectively. Both cavitation tubes are connected to the filter press;

[0009] The cavitation tube comprises an inlet section, a contraction section, a throat, a diffusion section and an outlet section. The diameter of the inlet section is 1 - 100 cm, the diameter of the throat is 0.1 - 15 cm, the diameter of the inlet section is 1 - 100 cm, and the diameters at both ends of the throat are equal;

[0010] The solid discharge pipe of the filter press is connected to a dechlorination silo. The wastewater reuse assembly comprises a steam compressor connected to the liquid discharge pipe of the filter press. One discharge port of the steam compressor is connected to a concentration tank, and the other discharge port of the steam compressor is connected to a water return tank.

[0011] Further, a controller for controlling the fly ash feeding amount and water inflow amount is provided on the stirring tank.

[0012] Note: The controller can automatically control the feeding amount of the fly ash silo and the mass concentration of the fly ash slurry inside the stirring tank, thus facilitating and ensuring subsequent staged hydrodynamic cavitation.

[0013] Further, the outlet end of the water return tank is connected to the stirring tank through a variable frequency pump, and a flowmeter is provided at the outlet end of the variable frequency pump.

[0014] Note: The water return tank collects recycled water to achieve the purpose of water resource conservation.

[0015] The present invention also provides a method for efficiently removing chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation. Based on the equipment for efficiently removing chlorides from municipal solid waste incineration fly ash according to any one of the above, the method comprises the following steps:

[0016] S1. Preparation of fly ash slurry: Add the fly ash to be treated in the fly ash silo into the stirring tank through the discharge pipe. At the same time, inject water into the stirring tank from the water storage tank or the water return tank and stir to obtain a fly ash slurry, and the mass concentration of the fly ash slurry is 5 - 45%;

[0017] S2. Hydraulic cavitation parameter fitting: Inject the prepared fly ash slurry into the cavitation tube through the peristaltic pump for hydraulic cavitation. The flow velocity at the throat of the cavitation tube during hydraulic cavitation is the cavitation flow velocity, and the cavitation flow velocity is 12 - 30 m / s. After hydraulic cavitation, the fly ash slurry is subjected to solid-liquid separation by the filter press to obtain fly ash residue and chlorine-containing wastewater. The fly ash residue enters the dechlorination silo, and the removal rate R of soluble chlorides is calculated. The optimal hydraulic cavitation parameter fitting formula is as follows:

[0018] R = aV 2 + bC 2 V + cC

[0019] In the formula, R is the removal rate of soluble chlorides in the fly ash slurry, in %; V is the cavitation flow velocity, in m / s; C is the mass concentration of the fly ash slurry, in %; a, b, and c are fitting parameters;

[0020] S3. Stepwise hydraulic cavitation:

[0021] S3-1. Determination of the optimal mass concentration: Prepare multiple portions of fly ash slurries with gradient mass concentrations from low to high, and perform hydraulic cavitation on each portion respectively. Control the cavitation flow velocity of all fly ash slurries to be the same, calculate the removal rate R of soluble chlorides in each portion of fly ash slurry, and substitute the values of R, V, and C of each portion of fly ash slurry into the fitting formula to calculate the optimal mass concentration for hydraulic cavitation of the fly ash slurry;

[0022] S3-2. Determination of the optimal cavitation flow velocity: Prepare multiple portions of fly ash slurries with the mass concentration being the optimal mass concentration, perform hydraulic cavitation on each portion respectively, control the cavitation flow velocity of all fly ash slurries to be set in a gradient from low to high, calculate the removal rate R of soluble chlorides in each portion of fly ash slurry, and substitute the values of R, V, and C of each portion of fly ash slurry into the fitting formula to calculate the optimal cavitation flow velocity of the fly ash slurry;

[0023] S4. Continuous hydraulic cavitation: Prepare the remaining fly ash in the fly ash silo into fly ash slurry according to the optimal mass concentration and perform continuous hydraulic cavitation at the optimal cavitation flow velocity;

[0024] S5. Post-treatment: Treat the chlorine-containing wastewater obtained by solid-liquid separation after step S3 stepwise hydraulic cavitation and step S4 continuous hydraulic cavitation through the wastewater reuse component to obtain reclaimed water.

[0025] Furthermore, the particle size of the fly ash to be treated in step S1 is below 200 mesh, the stirring speed of the fly ash to be treated in the stirring tank is 100 - 200 rpm, and the stirring time is 1 - 15 minutes.

[0026] Further, in the step S3-1, the fly ash slurries with gradient mass concentrations are fly ash slurries with mass concentrations of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, and 45% respectively, and the cavitation flow rates of all the fly ash slurries are controlled to be 14 m / s.

[0027] Note: By selecting fly ash slurries with gradient mass concentrations and substituting the results into the fitting formula, the optimal mass concentration can be obtained.

[0028] Further, in the step S3-2, when the cavitation flow rates are set in a gradient from low to high, the cavitation flow rates are sequentially controlled to be 12 m / s, 14 m / s, 16 m / s, 18 m / s, 20 m / s, 22 m / s, 24 m / s, 26 m / s, 28 m / s, and 30 m / s.

[0029] Note: By selecting gradient cavitation flow rates and substituting the results into the fitting formula, the optimal cavitation flow rate can be obtained.

[0030] Further, in the step S3-1, after a fly ash slurry with a certain mass concentration is prepared, it is injected into one of the cavitation tubes through the peristaltic pump and the three-way valve for hydrodynamic cavitation. Subsequently, clear water is injected through the water storage tank to wash the cavitation tube. The gate of the three-way valve is switched to connect the other cavitation tube with the peristaltic pump, and hydrodynamic cavitation of the next fly ash slurry with a different mass concentration is carried out. After completion, clear water is injected through the water storage tank to wash the cavitation tube, and the hydrodynamic cavitation of the fly ash slurries with gradient mass concentrations is completed in sequence through cyclic operation;

[0031] In the step S3-2, after a fly ash slurry is prepared, it is injected into one of the cavitation tubes through the peristaltic pump and the three-way valve for hydrodynamic cavitation. Subsequently, clear water is injected through the water storage tank to wash the cavitation tube. The gate of the three-way valve is switched to connect the other cavitation tube with the peristaltic pump, and the flow rate of the peristaltic pump is adjusted to the cavitation flow rate required for the next fly ash slurry, and hydrodynamic cavitation of the next fly ash slurry is carried out. After completion, clear water is injected through the water storage tank to wash the cavitation tube, and the hydrodynamic cavitation of the fly ash slurries with gradient cavitation flow rates is completed in sequence through cyclic operation.

[0032] Note: Through the cooperation of the three-way valve and the two cavitation tubes, fly ash slurries with different mass concentrations or flow rates can alternately pass through the two cavitation tubes, and after hydrodynamic cavitation is completed in one cavitation tube, clear water is used for washing to avoid interference of the residual fly ash slurry in the cavitation tube on the removal rate R of soluble chlorides in each fly ash slurry.

[0033] Further, in the step S5, the steps for treating the wastewater reuse component are as follows: the chloride salts precipitated after the chlorine-containing wastewater is evaporated by the steam compressor enter the concentration tank, and the water vapor generated by evaporation is condensed and enters the water return tank for recycling use.

[0034] Description: The recycled water obtained by treating wastewater through the wastewater recycling component can be used as the water source for preparing fly ash slurry, achieving the purpose of water resource conservation.

[0035] The beneficial effects of the present invention are as follows:

[0036] (1) The equipment and method for highly efficient removal of chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation of the present invention can effectively promote the dissolution of soluble chlorides through hydrodynamic cavitation, greatly improve the removal rate of soluble chlorides, and further reduce industrial water consumption. Moreover, the recycled water can be recycled, with low cost and good chloride removal effect. No chemical agents are used during the fly ash dechlorination process, and environmental protection and high-efficiency impurity removal of incinerated fly ash can be achieved.

[0037] (2) The equipment and method for highly efficient removal of chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation of the present invention optimize the parameters of hydrodynamic cavitation. The optimal mass concentration and optimal cavitation flow velocity are obtained through fitting formulas, and the cooperation of two cavitation tubes can determine the optimal parameters with high precision, and finally complete hydrodynamic cavitation efficiently. Brief Description of the Drawings

[0038] Figure 1 is the overall structural schematic diagram of the equipment for highly efficient removal of chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation of the present invention;

[0039] Figure 2 is the structural schematic diagram of the cavitation tube in the equipment for highly efficient removal of chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation of the present invention;

[0040] Figure 3 is the flow chart of the method for highly efficient removal of chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation of the present invention.

[0041] Among them, 1 - fly ash silo, 11 - discharge pipe, 2 - stirring tank, 21 - controller, 3 - peristaltic pump, 31 - three-way valve, 4 - cavitation tube, 41 - inlet section, 42 - contraction section, 43 - throat, 44 - diffusion section, 45 - outlet section, 5 - water storage tank, 6 - filter press, 61 - solid discharge pipe, 62 - liquid discharge pipe, 7 - wastewater recycling component, 71 - steam compressor, 72 - thickening tank, 73 - return water tank, 74 - variable frequency pump, 75 - flowmeter, 8 - dechlorination silo. Detailed Embodiments

[0042] Example 1

[0043] As Figure 1As shown in the figure, the device for efficiently removing chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation includes a fly ash silo 1, a stirring tank 2, a peristaltic pump 3, two cavitation tubes 4, a water storage tank 5, a filter press 6, and a wastewater recycling component 7. The discharge pipe 11 of the fly ash silo 1 is connected to the feed inlet of the stirring tank 2. The stirring tank 2 is provided with a controller 21 for controlling the fly ash feeding amount and water inflow amount. The controller 21 is a commercially available PLC controller. The discharge opening of the stirring tank 2 is connected to the peristaltic pump 3. The peristaltic pump 3 is respectively connected to the two cavitation tubes 4 through a three-way valve 31. The water storage tank 5 is respectively connected to the stirring tank 2 and the two cavitation tubes 4. Three water pumps are arranged inside the water storage tank 5 to supply water to the two cavitation tubes 4 and the stirring tank 2 respectively. The two cavitation tubes 4 are both connected to the filter press 6;

[0044] As Figure 2 shown in the figure, the cavitation tube 4 includes an inlet section 41, a contraction section 42, a throat 43, a diffusion section 44, and an outlet section 45. The diameter of the inlet section 41 is 32 cm, the diameter of the throat 43 is 8 cm, the diameter of the inlet section 41 is 32 cm, and the diameters at both ends of the throat 43 are equal;

[0045] As Figure 1 shown in the figure, the solid discharge pipe 61 of the filter press 6 is connected to a dechlorination silo 8. The wastewater recycling component 7 includes a steam compressor 71 connected to the liquid discharge pipe 62 of the filter press 6. One discharge port of the steam compressor 71 is connected to a thickening tank 72, and the other discharge port of the steam compressor 71 is connected to a water return tank 73. The outlet end of the water return tank 73 is connected to the stirring tank 2 through a variable frequency pump 74, and a flow meter 75 is provided at the outlet end of the variable frequency pump 74.

[0046] Example 2

[0047] The difference between this example and Example 1 is that:

[0048] The diameter of the inlet section 41 of the cavitation tube 4 is 1 cm, the diameter of the throat 43 is 0.1 cm, and the diameter of the inlet section 41 is 1 cm.

[0049] Example 3

[0050] The difference between this example and Example 1 is that:

[0051] The diameter of the inlet section 41 of the cavitation tube 4 is 75 cm, the diameter of the throat 43 is 10 cm, and the diameter of the inlet section 41 is 75 cm.

[0052] Example 4

[0053] The difference between this example and Example 1 is that:

[0054] The diameter of the inlet section 41 of the cavitation tube 4 is 100 cm, the diameter of the throat 43 is 15 cm, and the diameter of the inlet section 41 is 100 cm.

[0055] Note: The sizes of the components inside the cavitation tube 4 should be increased or decreased in proportion. A cavitation tube with a reasonable size should be selected according to the volume of fly ash slurry to be processed.

[0056] Example 5

[0057] This embodiment improves the method of efficiently removing chloride salts from waste incineration fly ash by hydraulic cavitation, based on the equipment for efficiently removing chloride salts from waste incineration fly ash by hydraulic cavitation in Example 1, such as Figure 3 As shown, the following steps are included:

[0058] S1, preparation of fly ash slurry: adding the fly ash to be treated in the fly ash silo 1 into the mixing barrel 2 through the discharge pipe 11, and injecting water into the mixing barrel 2 through the water storage tank 5 or the return water tank 73 and stirring to obtain fly ash slurry, the mass concentration of the fly ash slurry is 5-45%, the particle size of the fly ash to be treated is below 200 mesh, the stirring speed of the fly ash to be treated in the mixing barrel 2 is 150rpm, and the stirring time is 10 minutes;

[0059] S2. Hydraulic cavitation parameter fitting: The prepared fly ash slurry is injected into the cavitation tube 4 through the peristaltic pump 3. The flow rate range of the peristaltic pump 3 is 100-500m 3 / h, the pressure value range is 0.2~15.0MPa, the flow rate of the fly ash slurry in the throat is adjusted by adjusting the flow pressure of the peristaltic pump, and hydraulic cavitation is performed. During hydraulic cavitation, the flow rate of the throat 43 of the cavitation tube 4 is the cavitation flow rate, and the cavitation flow rate is 12~30m / s. The fly ash slurry after hydraulic cavitation passes through the filter press 6 for solid-liquid separation to obtain fly ash slag and chlorine-containing wastewater, and the fly ash slag enters the dechlorination silo 8. The removal rate R of soluble chloride salts is calculated. The optimal hydraulic cavitation parameter fitting formula is as follows:

[0060] R=aV 2 +bC 2 V+c

[0061] Where, R is the removal rate of soluble chloride salts in fly ash slurry, in %; V is the cavitation velocity, in m / s; C is the mass concentration of fly ash slurry, in %; a, b, c are fitting parameters;

[0062] The calculation formula for the removal rate R of soluble chloride salts in fly ash slurry is as follows:

[0063]

[0064] W0 and W1 are the mass fractions of soluble chloride salts in fly ash before and after impurities removal, respectively, in %;

[0065] S3, segmented hydraulic cavitation:

[0066] S3-1. Determination of the optimal mass concentration: Prepare multiple portions of fly ash slurry with gradient mass concentrations in ascending order, and perform hydrodynamic cavitation on each portion respectively. Control the cavitation flow velocity of all fly ash slurries to be the same at 14 m / s. Calculate the removal rate R of soluble chlorides in each portion of fly ash slurry, and substitute the values of R, V, and C of each portion of fly ash slurry into the fitting formula to calculate the optimal mass concentration of hydrodynamic cavitation of fly ash slurry. The fly ash slurries with gradient mass concentrations are fly ash slurries with mass concentrations of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, and 45% respectively. After a portion of fly ash slurry with a certain mass concentration is prepared, it is injected into one of the cavitation tubes 4 through the peristaltic pump 3 and the three-way valve 31 for hydrodynamic cavitation. Subsequently, clean water is injected through the water storage tank 5 to wash the cavitation tube 4. Switch the gate of the three-way valve 31 to connect the other cavitation tube 4 with the peristaltic pump 3 to perform hydrodynamic cavitation on the next portion of fly ash slurry with a different mass concentration. After completion, clean water is injected through the water storage tank 5 to wash the cavitation tube 4, and the hydrodynamic cavitation of fly ash slurries with gradient mass concentrations is completed in sequence by cycling;

[0067] S3-2. Determination of the optimal cavitation flow velocity: Prepare multiple portions of fly ash slurry, all with the optimal mass concentration, and perform hydrodynamic cavitation on each portion respectively. Control the cavitation flow velocity of all fly ash slurries to be set in gradients from low to high. Calculate the removal rate R of soluble chlorides in each portion of fly ash slurry, and substitute the values of R, V, and C of each portion of fly ash slurry into the fitting formula to calculate the optimal cavitation flow velocity of fly ash slurry. When the cavitation flow velocity is set in gradients from low to high, the cavitation flow velocity is controlled to be 12 m / s, 14 m / s, 16 m / s, 18 m / s, 20 m / s, 22 m / s, 24 m / s, 26 m / s, 28 m / s, and 30 m / s in sequence. After a portion of fly ash slurry is prepared, it is injected into one of the cavitation tubes 4 through the peristaltic pump 3 and the three-way valve 31 for hydrodynamic cavitation. Subsequently, clean water is injected through the water storage tank 5 to wash the cavitation tube 4. Switch the gate of the three-way valve 31 to connect the other cavitation tube 4 with the peristaltic pump 3, and adjust the flow rate of the peristaltic pump 3 to the cavitation flow velocity required for the next portion of fly ash slurry to perform hydrodynamic cavitation on the next portion of fly ash slurry. After completion, clean water is injected through the water storage tank 5 to wash the cavitation tube 4, and the hydrodynamic cavitation of fly ash slurries with gradient cavitation flow velocities is completed in sequence by cycling;

[0068] When cleaning the cavitation tube 4, ensure that the liquid discharged from the cavitation tube 4 after cleaning is properly disposed of separately to avoid affecting the calculation results;

[0069] S4. Continuous hydrodynamic cavitation: Prepare the remaining fly ash in the fly ash silo 1 into fly ash slurry according to the optimal mass concentration and perform continuous hydrodynamic cavitation according to the optimal cavitation flow velocity;

[0070] S5. Post-treatment: The chlorine-containing wastewater obtained by solid-liquid separation after the step S3 of segmented hydrodynamic cavitation and the step S4 of continuous hydrodynamic cavitation is treated by the wastewater reuse component 7 to obtain recycled water. The treatment steps of the wastewater reuse component 7 are as follows: The chloride salts precipitated after the chlorine-containing wastewater is evaporated by the steam compressor 71 enter the concentration tank 72, and the water vapor generated by evaporation enters the return water tank 73 through condensation for recycling.

[0071] Example 6

[0072] The difference between this example and Example 5 is as follows:

[0073] The fly ash to be treated is stirred in the stirring tank 2 at a stirring speed of 100 rpm for 1 minute.

[0074] Example 7

[0075] The difference between this example and Example 5 is as follows:

[0076] The fly ash to be treated is stirred in the stirring tank 2 at a stirring speed of 200 rpm for 15 minutes.

[0077] Note: When obtaining the fly ash slurry by stirring, the stirring speed and stirring time are reasonably adjusted according to the mass concentration of the target fly ash slurry. For example, when the mass concentration is 5%, the stirring speed is 100 rpm and the stirring time is 1 minute; when the mass concentration is 10%, the stirring speed is 110 rpm and the stirring time is 3 minutes; when the mass concentration is 15%, the stirring speed is 120 rpm and the stirring time is 5 minutes; when the mass concentration is 20%, the stirring speed is 130 rpm and the stirring time is 7 minutes, and so on. By analogy, when the mass concentration is 45%, the stirring speed is 200 rpm and the stirring time is 15 minutes.

[0078] Experimental Example

[0079] A field simulation experiment was carried out according to the method and related equipment in Example 5. After the end of step S3-1, the removal rates R of soluble chloride salts in the fly ash slurries with gradient mass concentrations of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, and 45% are shown in Table 1:

[0080] Table 1 Removal rates of soluble chloride salts in fly ash slurries at gradient mass concentrations

[0081]

[0082]

[0083] After fitting the R in Table 1 with the fitting formula, the fitting relationship between R and C is obtained as:

[0084] R = -0.099C 2 + 4.43C + 31.89

[0085] r 2 = 96; where a = 0.162716, b = -0.00709, c = 4.43052;

[0086] When C is 22.32, the maximum value of R is 81.34. At this time, the soluble chloride salt content is 3.73%, which is not much different from the maximum value of R in the actual test. Therefore, the optimal slurry concentration is determined to be 22.32%.

[0087] After step S3-2 ends, the removal rates R of soluble chloride salts in fly ash slurries with cavitation flow velocities controlled successively at 12 m / s, 14 m / s, 16 m / s, 18 m / s, 20 m / s, 22 m / s, 24 m / s, 26 m / s, 28 m / s, and 30 m / s are shown in Table 2:

[0088] Table 2 Removal rates of soluble chloride salts in fly ash slurries at gradient cavitation flow velocities

[0089]

[0090]

[0091] After fitting the R in Table 2 with the fitting formula, the fitting relationship between R and V is obtained as:

[0092] R = -0.13V 2 + 6.42C 2 V + 19.28C

[0093] r 2 = 97; where a = -0.13424, b = 0.012883, c = 0.863637.

[0094] When V is 23.91, the maximum value of R is 95.99. At this time, the soluble chloride salt content is 0.799%.

[0095] Parameter verification test and blank control test: Conduct tests respectively with a fly ash slurry mass concentration of 22.32% and a cavitation flow velocity of 23.91 m / s, and keep the rest of the experimental operations unchanged to verify the accuracy of the parameters fitted by this fitting formula. At the same time, stir the fly ash slurry with a mass concentration of 22.32% for 10 minutes, then perform solid-liquid separation, and then dry and detect it as the blank group for the non-cavitation test. The experimental results are shown in Table 3.

[0096] Table 3 Results of parameter verification test and blank control test

[0097] Test category Soluble chloride salt content % Removal rate of soluble chloride salt R% Parameter verification test 0.795 96.02 Blank control test 5.356 73.18 Raw ore 19.97 -

[0098] As can be seen from Table 3, when the experiment was carried out with a fly ash slurry mass concentration of 22.32% and a cavitation flow velocity of 23.91 m / s, the soluble chloride salt content was 0.795%, indicating that the fitting formula can accurately predict the slurry concentration and the slurry flow velocity at the throat of the cavitation tube during the fly ash cavitation dechlorination process. On the other hand, the blank control experiment found that when the method of this invention patent was not used for the experiment, the soluble chloride salt content was still as high as 5.356%, and the soluble chloride salt removal rate was only 73.18%. This shows that the method of this invention can efficiently remove the soluble chloride salt in fly ash.

Claims

1. A method for efficiently removing chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation, based on an apparatus for efficiently removing chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation, characterized in that, The equipment comprises a fly ash silo (1), a mixing barrel (2), a peristaltic pump (3), two cavitation tubes (4), a water storage tank (5), a filter press (6) and a wastewater recycling component (7); the discharge pipe (11) of the fly ash silo (1) is connected to the feed port of the mixing barrel (2); the discharge port of the mixing barrel (2) is connected to the peristaltic pump (3); the peristaltic pump (3) is respectively connected to the two cavitation tubes (4) via a three-way valve (31); the water storage tank (5) is respectively connected to the mixing barrel (2) and the two cavitation tubes (4); and the two cavitation tubes (4) are both connected to the filter press (6); The cavitation tube (4) comprises an inlet section (41), a contraction section (42), a throat (43), a diffusion section (44) and an outlet section (45); the diameter of the inlet section (41) is 1 to 100 cm, the diameter of the throat (43) is 0.1 to 15 cm, the diameter of the inlet section (41) is 1 to 100 cm, and the diameters at both ends of the throat (43) are equal; The solid discharge pipe (61) of the filter press (6) is connected to the dechlorination silo (8), and the wastewater recycling component (7) comprises a steam compressor (71) connected to the liquid discharge pipe (62) of the filter press (6), one discharge port of the steam compressor (71) is connected to the concentration tank (72), and the other discharge port of the steam compressor (71) is connected to the return water tank (73). The method comprises the following steps: S1. Preparation of fly ash slurry: adding the fly ash to be treated in the fly ash silo (1) into the mixing barrel (2) through the discharge pipe (11), and injecting water into the mixing barrel (2) through the water storage tank (5) or the return water tank (73) and stirring to obtain fly ash slurry, wherein the mass concentration of the fly ash slurry is 5-45%; S2. Fitting of hydraulic cavitation parameters: The prepared fly ash slurry is injected into the cavitation tube (4) through the peristaltic pump (3) to perform hydraulic cavitation. The flow velocity at the throat (43) of the cavitation tube (4) during hydraulic cavitation is the cavitation velocity, and the cavitation velocity is 12-30 m / s. The fly ash slurry after hydraulic cavitation is passed through the filter press (6) for solid-liquid separation to obtain fly ash residue and chlorine-containing wastewater. The fly ash residue enters the dechlorination silo (8). The removal rate R of soluble chloride salts is calculated. The optimal hydraulic cavitation parameter fitting formula is as follows: In the formula, R is the removal rate of soluble chlorides in fly ash slurry, with the unit of %; V is the cavitation flow velocity, with the unit of m / s; C is the mass concentration of fly ash slurry, with the unit of %; a, b, and c are fitting parameters; S3, segmented hydraulic cavitation: S3-1. Determination of the optimal mass concentration: prepare multiple fly ash slurries with gradient mass concentrations from low to high, perform hydraulic cavitation on each of them, control the cavitation flow rate of all fly ash slurries to be the same, calculate the removal rate R of soluble chloride salts in each fly ash slurry, and bring the values of R, V, and C of each fly ash slurry into the fitting formula to calculate the optimal mass concentration of the fly ash slurry for hydraulic cavitation; S3-2. Determination of the optimal cavitation flow rate: Prepare multiple portions of fly ash slurry with a mass concentration of the optimal mass concentration, and perform hydrodynamic cavitation on each portion respectively. Control the cavitation flow rate of all fly ash slurries to be set in a gradient from low to high. Calculate the removal rate R of soluble chlorides in each portion of fly ash slurry, and substitute the values of R, V, and C of each portion of fly ash slurry into the fitting formula to calculate the optimal cavitation flow rate of the fly ash slurry. S4. Continuous hydrodynamic cavitation: Prepare the remaining fly ash in the fly ash silo (1) into fly ash slurry according to the optimal mass concentration, and perform continuous hydrodynamic cavitation according to the optimal cavitation flow rate. S5. Post-treatment: Treat the chlorine-containing wastewater obtained by solid-liquid separation after the step S3 of segmented hydrodynamic cavitation and the step S4 of continuous hydrodynamic cavitation through the wastewater reuse component (7) to obtain recycled water.

2. The method for efficiently removing chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation according to claim 1, wherein A controller (21) for controlling the fly ash feeding amount and water inflow is provided on the stirring tank (2).

3. The method for efficiently removing chlorides in municipal solid waste incineration fly ash by hydrodynamic cavitation according to claim 1, characterized in that The outlet end of the return water tank (73) is connected to the stirring tank (2) through a variable-frequency pump (74), and a flow meter (75) is provided at the outlet end of the variable-frequency pump (74).

4. The method for efficiently removing chlorides from waste incineration fly ash by hydrodynamic cavitation according to claim 1, characterized in that In the step S1, the particle size of the fly ash to be treated is below 200 mesh, the stirring speed of the fly ash to be treated in the stirring tank (2) is 100 - 200 rpm, and the stirring time is 1 - 15 minutes.

5. The method for efficiently removing chlorides from waste incineration fly ash by hydrodynamic cavitation according to claim 1, characterized in that, In the step S3-1, the fly ash slurries with gradient mass concentrations are fly ash slurries with mass concentrations of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, and 45% respectively, and the cavitation flow rate of all fly ash slurries is controlled to be 14 m / s.

6. The method for efficiently removing chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation according to claim 1, characterized in that In the step S3-2, when the cavitation flow rate is set in a gradient from low to high, the cavitation flow rate is sequentially controlled to be 12 m / s, 14 m / s, 16 m / s, 18 m / s, 20 m / s, 22 m / s, 24 m / s, 26 m / s, 28 m / s, and 30 m / s.

7. The method for efficiently removing chlorides from waste incineration fly ash by hydrodynamic cavitation according to claim 1, wherein In the step S3-1, after a fly ash slurry with a certain mass concentration is prepared, it is injected into one of the cavitation tubes (4) through the peristaltic pump (3) and the three-way valve (31) for hydrodynamic cavitation. Subsequently, clear water is injected into the cavitation tube (4) through the water storage tank (5). Switch the gate of the three-way valve (31) to connect the other cavitation tube (4) with the peristaltic pump (3) to perform hydrodynamic cavitation on the fly ash slurry with the next mass concentration. After completion, clear water is injected into the cavitation tube (4) through the water storage tank (5), and the hydrodynamic cavitation of the fly ash slurries with gradient mass concentrations is completed in sequence by cycling. In the step S3-2, after a fly ash slurry is prepared, it is injected into one of the cavitation tubes (4) through the peristaltic pump (3) and the three-way valve (31) for hydrodynamic cavitation. Subsequently, clear water is injected into the cavitation tube (4) through the water storage tank (5). Switch the gate of the three-way valve (31) to connect the other cavitation tube (4) with the peristaltic pump (3), and adjust the flow rate of the peristaltic pump (3) to the cavitation flow rate required for the next fly ash slurry to perform hydrodynamic cavitation on the next fly ash slurry. After completion, clear water is injected into the cavitation tube (4) through the water storage tank (5), and the hydrodynamic cavitation of the fly ash slurries with gradient cavitation flow rates is completed in sequence by cycling.

8. The method for efficiently removing chlorides from municipal solid waste incineration fly ash by hydrodynamic cavitation according to claim 1, characterized in that The steps of treating by the wastewater reuse component (7) in the step S5 are as follows: the chloride salts precipitated after the chlorine-containing wastewater is evaporated by the steam compressor (71) enter the concentration tank (72), and the water vapor generated by evaporation enters the water return tank (73) through condensation for recycling.

Images