Low-carbon treatment process for waste water from water washing of household garbage incineration fly ash

Abstract

The present application belongs to the technical field of waste incineration fly ash treatment, and particularly relates to a low-carbon treatment process for waste incineration fly ash water washing wastewater, which comprises the following steps: A1: water washing of waste incineration fly ash to wash and remove heavy metals in the fly ash; A2: water washing wastewater is removed of heavy metals by ferrous chloride and sulfide; A3: water washing wastewater after removal of heavy metals is mixed with sodium sulfate to remove calcium ions; A4: residual calcium ions are removed by sodium carbonate, and sodium carbonate removal liquid is subjected to plate and frame pressure filtration and then enters an ultrafiltration and nanofiltration membrane system, and concentrated liquid of the membrane system is returned to configure a sodium sulfate solution; A5: fresh water from the membrane system enters an evaporation system, and mother liquor of the evaporation system is first subjected to diatomite reaction and then enters a raw ash pre-slurry reaction tank for raw ash slurry, so that the above low-carbon process is used to reduce the amount of sodium carbonate and the amount of mother liquor treatment, and efficient and low-carbon treatment of waste incineration fly ash water washing wastewater can be realized.

Description

Technical Field

[0001] This invention belongs to the field of waste incineration fly ash treatment technology, specifically a low-carbon treatment process for wastewater washing from municipal solid waste incineration fly ash. Background Technology

[0002] As the mainstream of municipal solid waste treatment gradually shifts from sanitary landfill to incineration, fly ash from municipal solid waste incineration has become a significant pollutant. Fly ash refers to the residue collected in the flue gas purification system of municipal solid waste incineration power plants. Components with high content in fly ash include calcium chloride, calcium hydroxide, calcium sulfate, and calcium hydroxide. According to the "Standard for Pollution Control of Municipal Solid Waste Incineration" (GB18485-2014), "Fly ash from municipal solid waste incineration should be managed as hazardous waste." Therefore, fly ash must be collected separately and must not be mixed with municipal solid waste, incineration residue, or other hazardous waste.

[0003] Chinese patent CN115254923B describes a process for preparing high-purity calcium sulfate using fly ash from waste incineration. It mainly utilizes sulfate ions to prepare high-purity calcium sulfate, but it lacks a complete consideration of the subsequent evaporation of sulfate ions replacing carbonate ions and the entire system, and it also lacks consideration of the impact of sulfate ions remaining in the system on the process.

[0004] Chinese patent CN112777906B discloses a high-efficiency fly ash washing sludge dewatering process for municipal solid waste incineration, which solves the problem of plate and frame clogging during the dewatering process. Solving the problem of plate and frame clogging can also improve the complete operation of the system, which will not be described in detail here.

[0005] Chinese patent CN115138022B discloses a method for dechlorinating fly ash from municipal solid waste incineration. The method involves mixing fly ash from municipal solid waste incineration with a specially formulated dechlorinating agent to obtain a mixture; then sintering the mixture to form dechlorinated fly ash and gaseous chlorosilane; finally, liquid-phase absorption of the exhaust gas is performed, simultaneously recovering the dechlorinating agent and generating hydrochloric acid. The former is reused, and the latter is recycled. The dechlorinating agent used is quartz, which did not effectively promote the water washing process.

[0006] Chinese patent CN109396162B discloses an energy-saving treatment process for fly ash from waste incineration, comprising steps of fly ash washing, heavy metal removal, decolorization, calcium removal, and evaporation crystallization, or steps of fly ash washing, heavy metal removal, decolorization, and evaporation crystallization. The fly ash washing is a multi-stage counter-current washing process. The washing liquid from the final stage of the multi-stage counter-current washing is subjected to reverse osmosis membrane desalination treatment. The purified water produced by the reverse osmosis membrane desalination treatment is reused as the water source for the final stage washing, and the concentrated water produced by the reverse osmosis membrane desalination treatment is used as the water source for the next stage washing. The mass ratio of fly ash to water in the first stage washing is controlled to be 1:1-1.1. After the first stage washing, solid-liquid separation is performed. The solid is pulverized and enters the next stage washing, while the liquid enters the heavy metal removal step. This invention can significantly reduce energy consumption during evaporation crystallization and lower production costs without increasing the number of washing stages.

[0007] Chinese Invention Patent 202311326463.2 discloses a method for preparing calcium fluoride from municipal solid waste incineration fly ash. The method involves first acid washing / water washing of the fly ash to obtain an aqueous fly ash slurry. The slurry undergoes solid-liquid separation to obtain a high-calcium-content crude brine, with the solids proceeding to the next stage. The high-calcium-content crude brine undergoes a degravation process, followed by settling. The clarified liquid then undergoes denitrification, oxidation, and neutralization reactions, resulting in a high-calcium-content refined brine. Pretreated waste hydrofluoric acid is added to the high-calcium-content refined brine and stirred thoroughly, resulting in solid-liquid separation. The obtained solids undergo three-stage countercurrent oxygen washing, followed by thermal desorption and catalytic thermal pyrolysis to obtain the calcium fluoride product. However, this process is only suitable for preparing relatively low-grade calcium chloride, as it contains many impurities that affect its usability.

[0008] The aforementioned fly ash washing wastewater treatment technologies failed to systematically combine the requirements of low-carbon and high-efficiency treatment processes. Innovative research was conducted in the fields of water-ash ratio control, calcium carbonate product control, membrane system application, and efficient treatment of evaporation mother liquor, resulting in a waste incineration fly ash washing wastewater treatment process with low-carbon properties.

[0009] Therefore, the present invention provides a low-carbon treatment process for fly ash washing wastewater from municipal solid waste incineration. Summary of the Invention

[0010] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0011] The technical solution adopted by this invention to solve its technical problem is: a low-carbon treatment process for fly ash washing wastewater from municipal solid waste incineration, as described in this invention.

[0012] A1: The traditional three-stage countercurrent rinsing process is used to wash the fly ash from waste incineration with water to remove heavy metals from the fly ash and allow it to enter the liquid phase;

[0013] A2: The washing wastewater is treated by water treatment processes. In the heavy metal removal section, ferrous chloride and sodium sulfide are used for precipitation treatment.

[0014] A3: The deweighted washing wastewater is first transported to the reaction tank through the inlet. Then, sodium sulfate is put into the weighing and dissolving tank through the feeding component and discharged through the conveying component to contact the washing wastewater entering the reaction tank. Finally, the deweighted washing wastewater and sodium sulfate are mixed through the mixing component to remove calcium ions from the washing wastewater.

[0015] A4: The remaining calcium ions are removed using sodium carbonate. The sodium carbonate removal solution is then filtered through a plate and frame filter press and then enters the ultrafiltration and nanofiltration membrane system. The concentrate from the membrane system is refluxed to the sodium sulfate preparation system for the preparation of sodium sulfate solution.

[0016] A5: Freshwater from the membrane system enters the evaporation system. The mother liquor from the evaporation system first undergoes a diatomaceous earth reaction and precipitation, and then enters the raw ash pre-slurry reaction tank for raw ash slurry preparation.

[0017] The liquid inlet is located at the top of the reaction vessel;

[0018] The mixing assembly includes a rotating rod, a stirring rod, and a power assembly. The rotating rod is rotatably mounted inside the reaction vessel, and the stirring rod is fixedly mounted on the outer wall of the rotating rod. The rotation of the rotating rod is controlled by the power assembly.

[0019] The power assembly includes a drive motor, a drive wheel, and a driven wheel. The drive motor is fixedly installed at the top of the reaction vessel. The drive wheel is fixedly connected to the output shaft of the drive motor. The driven wheel is fixedly installed on the outer wall of the rotating rod. The drive wheel and the driven wheel are connected by a belt.

[0020] A flow guide block is fixedly installed inside the reaction vessel. The top of the flow guide block is open and tilted downwards towards the rotating rod. A filter plate is fixedly installed inside the liquid inlet. The filter plate is located directly above the flow guide block. The wastewater from the weight removal process passes through the filter plate and flows onto the flow guide block.

[0021] The conveying assembly includes a weighing and dissolving tank, a conveying auger, a water inlet, and a water outlet. The weighing and dissolving tank is hollow and fixedly installed inside the reaction vessel. The rotating rod passes through the weighing and dissolving tank. The conveying auger is located inside the weighing and dissolving tank and is fixedly installed on the outer wall of the rotating rod. The water inlet is opened on the bottom outer wall of the weighing and dissolving tank. The water outlet is located on the top outer wall of the weighing and dissolving tank and is located above the guide block.

[0022] The solution inside the reaction tank enters the weighing and dissolving tank through the inlet, and is discharged from the outlet pipe by a conveying auger to mix with the washing wastewater flowing on the guide block.

[0023] The feeding assembly includes a feeding port and holes. The rotating rod has a cavity inside. The feeding port is located at the top of the rotating rod and communicates with the cavity inside. The holes are located on the outer wall of the rotating rod. There are multiple holes, and all of the holes are located inside the weighing and dissolving tank.

[0024] A rotating rod is rotatably mounted on the stirring rod, a rotating ring is rotatably mounted on the outer wall of the rotating rod, and a stirring blade is fixedly mounted on the outer wall of the rotating ring.

[0025] The reaction vessel is equipped with multiple blocking rods fixedly installed inside its interior.

[0026] When the rotating rod drives the stirring rod to rotate, the rotating rod will drive the stirring blade to rotate synchronously. The stirring blade will rotate along the axis of the rotating rod due to the obstruction of the blocking rod.

[0027] The guide block is fixedly mounted with a first mounting bracket and a second mounting bracket. A water turbine blade is rotatably mounted on the first mounting bracket, and a striking plate is elastically mounted on the second mounting bracket via a torsion spring.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. The present invention provides a low-carbon treatment process for fly ash washing wastewater from municipal solid waste incineration. This process offers a significant carbon reduction and economical low-carbon treatment method for fly ash washing wastewater from waste incineration, saving costs while maximizing compliance with the requirements of low-carbon development. Through low-carbon processes such as sulfate replacement of carbonate decalcification, ultrafiltration / nanofiltration membrane interception of sulfate ions, diatomaceous earth adsorption of evaporation mother liquor, and slurry adsorption of evaporation mother liquor, efficient and low-carbon treatment of fly ash washing wastewater can be achieved.

[0030] 2. The low-carbon treatment process for fly ash washing wastewater from municipal solid waste incineration described in this invention not only has significant economic advantages, reducing costs by more than 50%, but also allows for continuous feeding and discharging throughout the entire process, ensuring stable operation of the entire system. Furthermore, the method is simple to operate, highly adaptable, and suitable for the treatment needs of fly ash washing wastewater of different scales and with different sulfate and chlorine contents, while also having numerous practical applications to support it.

[0031] 3. The present invention provides a low-carbon treatment process for fly ash washing wastewater from municipal solid waste incineration. Solid sodium sulfate is fed into a weighing and dissolving tank through a feeding port. A drive motor controls a rotating rod to drive a stirring rod and a conveying auger to rotate synchronously. The solution in the weighing and dissolving tank is discharged from the outlet pipe and impacts the washing wastewater flowing on the guide block for pre-mixing. The stirring rod and stirring blades further enhance the effect of sodium sulfate in removing calcium ions inside the reaction tank. Attached Figure Description

[0032] The invention will now be further described with reference to the accompanying drawings.

[0033] Figure 1 This is a perspective view of the present invention;

[0034] Figure 2 This is a cross-sectional view of the reaction vessel in this invention;

[0035] Figure 3 In this invention Figure 2 Enlarged view of point A in the image;

[0036] Figure 4 This is a schematic diagram of the hole structure in this invention;

[0037] Figure 5 In this invention Figure 4 Enlarged view of point B in the image;

[0038] Figure 6 This is a schematic diagram of the reconstituted drug tank in this invention;

[0039] Figure 7 This is a schematic diagram of the flow guide block in this invention;

[0040] Figure 8 In this invention Figure 7 Enlarged view of point C in the image;

[0041] Figure 9 This is a process flow diagram of the present invention.

[0042] In the diagram: 1. Reaction vessel; 2. Rotating rod; 3. Liquid inlet; 4. Drive motor; 5. Driving wheel; 6. Driven wheel; 7. Guide block; 8. Filter plate; 9. Water outlet pipe; 10. Weighing and dissolving tank; 11. Water inlet; 12. Stirring rod; 13. Conveying auger; 14. Rotating rod; 15. Rotating ring; 16. Stirring blade; 17. Blocking rod; 18. First mounting frame; 19. Water wheel blade; 20. Impact plate; 21. Second mounting frame; 22. Feeding port; 23. Hole. Detailed Implementation

[0043] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0044] Example 1: As Figure 9 As shown in the embodiment of the present invention, a low-carbon treatment process for fly ash washing wastewater from municipal solid waste incineration includes the following steps:

[0045] A1: The traditional three-stage countercurrent rinsing process is used to wash the fly ash from waste incineration with water to remove heavy metals from the fly ash and allow it to enter the liquid phase;

[0046] A2: The washing wastewater is treated by water treatment processes. In the heavy metal removal section, ferrous chloride and sodium sulfide are used for precipitation treatment.

[0047] A3: The deweighted washing wastewater is first transported to the reaction tank 1 through the inlet 3. Then, sodium sulfate is put into the weighing and dissolving tank 10 through the feeding component and discharged through the conveying component to contact the washing wastewater entering the reaction tank 1. Finally, the deweighted washing wastewater and sodium sulfate are mixed through the mixing component to remove calcium ions from the washing wastewater.

[0048] A4: The remaining calcium ions are removed using sodium carbonate. The sodium carbonate removal solution is then filtered through a plate and frame filter press and then enters the ultrafiltration and nanofiltration membrane system. The concentrate from the membrane system is refluxed to the sodium sulfate preparation system for the preparation of sodium sulfate solution.

[0049] A5: Freshwater from the membrane system enters the evaporation system. The mother liquor from the evaporation system first undergoes a diatomaceous earth reaction and precipitation, and then enters the raw ash pre-slurry reaction tank for raw ash slurry preparation.

[0050] The fly ash washing process for waste incineration employs a traditional three-stage countercurrent rinsing process to wash away calcium, chloride, sodium, potassium, and sulfate ions from the fly ash, ensuring that the chloride content of the washed fly ash is less than 1%. Simultaneously, it maximizes the dissolution of soluble heavy metals from the fly ash into the liquid phase. Part of the washing wastewater is recycled to the first-stage washing process. This wastewater is then treated in the water treatment section. The heavy metal removal section uses ferrous chloride and sodium sulfide for precipitation. After heavy metal removal, the wastewater is first treated with sodium sulfate to remove calcium ions. The remaining calcium ions are then removed using sodium carbonate. The sodium carbonate removal solution is filtered through a plate and frame filter press and then enters the ultrafiltration and nanofiltration membrane systems. Calcium carbonate is subsequently decomposed into carbon dioxide in the cement kiln. The concentrate from the membrane system is recycled to the sodium sulfate preparation system, further reducing sodium sulfate usage and thus reducing carbon emissions from a raw material perspective. The desalinated water from the membrane system enters the evaporation system, and the condensate from the evaporation is reused in the washing process. The mother liquor from the evaporation system first undergoes a diatomaceous earth reaction and precipitation process, and then enters the raw ash pre-slurry reaction tank for raw ash slurry preparation, reducing the amount of mother liquor discharged and lowering energy consumption compared to steam drying of the mother liquor.

[0051] As a preferred option, the reflux ratio of the primary water washing filtrate is 30%-90%, thus the water-ash ratio in the water washing process is 1-1.5:1 (mass ratio);

[0052] As a preferred option, sodium sulfate removes 80-90% of the total calcium ions, and the remaining calcium ions are removed by sodium carbonate, controlling the calcium ion concentration entering the evaporator to be less than 10 mg / L;

[0053] As a preferred option, the water production rate of the ultrafiltration / nanofiltration system is 50-70%.

[0054] As a preferred option, the discharge rate of the mother liquor from evaporation is 2-3% of the evaporation rate, and the temperature after discharge is controlled to be less than 40°C by a heat exchanger.

[0055] As a preferred option, the concentration of diatomaceous earth added to the evaporation mother liquor is 10-50 times the TOC concentration.

[0056] The fly ash washing process for waste incineration employs a traditional three-stage countercurrent rinsing process to remove calcium, chloride, sodium, potassium, and sulfate ions from the fly ash. The water-to-ash ratio is set at 1.5:1 (mass ratio), and the chloride content of the washed fly ash is less than 0.8%. Simultaneously, it maximizes the dissolution of soluble heavy metals in the fly ash, allowing them to enter the liquid phase. The recirculation ratio of the washed wastewater to the primary washing process is set at 60%.

[0057] The wastewater is treated using a liquid-phase water treatment process. In the heavy metal removal section, ferrous chloride and sodium sulfide are used for precipitation. The sodium sulfide dosage is 20 times the concentration of dissolved heavy metals, and the ferrous chloride dosage is the same mass as the sodium sulfide. After heavy metal removal, the washing wastewater is first treated with sodium sulfate to remove calcium ions, with a calcium ion concentration of 18000 mg / L. After sodium sulfate addition, the remaining calcium ion concentration is 1800 mg / L. After adding sodium carbonate, the remaining calcium ion concentration is 8.6 mg / L. The sulfate ion concentration after ultrafiltration / nanofiltration is less than 1%. 00 mg / L enters the subsequent evaporation system. The circulation rate of the evaporation mother liquor is 2.6%, and the discharge treatment rate is 0.46% of the evaporation rate. The mother liquor in the evaporation system is first precipitated by diatomaceous earth reaction at a concentration of 10000 mg / L, and then enters the raw ash pre-slurry reaction tank for raw ash slurrying. The powdered activated carbon containing 0.4% in fly ash adsorbs the harmful components in the mother liquor, reducing the amount of evaporation mother liquor discharged, thus forming a stable water washing wastewater treatment process, while greatly reducing carbon emissions during the water washing process.

[0058] The method of this invention utilizes the widely available and stable wastewater from the fly ash washing process of municipal solid waste incineration for process development and research. It has a spectral range and, while pursuing high treatment efficiency, meets the requirements for low-carbon treatment.

[0059] The process employed in this invention not only boasts significant economic advantages, reducing costs by more than 50%, but also allows for continuous feeding and discharging throughout the entire process, ensuring stable operation of the entire system. Furthermore, the method is simple to operate, highly adaptable, and suitable for treating fly ash washing wastewater of different scales and with varying sulfate and chlorine contents. It also has numerous practical applications to support its effectiveness.

[0060] This invention provides a low-carbon treatment process for fly ash washing wastewater from waste incineration that significantly reduces carbon emissions and is economical. While saving costs, it maximizes compliance with low-carbon development requirements. Through low-carbon processes such as sulfate replacement of carbonate decalcification, ultrafiltration / nanofiltration membrane interception of sulfate ions, diatomaceous earth adsorption in the evaporation mother liquor, and slurry adsorption in the evaporation mother liquor, efficient and low-carbon treatment of fly ash washing wastewater can be achieved. After treatment with this process, carbon emissions during the fly ash washing wastewater treatment process can be reduced by more than 40%, and the process operation is stable.

[0061] Experimental data:

[0062] The carbon emission reduction of the sodium sulfate process for fly ash washing wastewater treatment is calculated as follows:

[0063] 1) Assuming 1 ton of fly ash produces 3 tons of washing liquid, and the average concentration of calcium ions in the washing liquid is 18000 mg / L, which is 18 kg / ton, then 54 kg of calcium ions need to be removed from 1 ton of fly ash. The precipitation reaction formula is:

[0064] Ca 2+ +Na₂SO₄——CaSO₄(s)+2Na + Equation 1 - Sodium Sulfate Method

[0065] Ca 2+ +Na₂CO₃——CaCO₃(s)+2Na + Equation 2 - Sodium Carbonate Method

[0066] 2) Removing 1 kg of calcium ions requires adding 3.55 kg of sodium sulfate, while simultaneously generating 3.4 kg of calcium sulfate.

[0067] Removing 1 kg of calcium ions requires adding 2.65 kg of sodium carbonate, while simultaneously generating 2.5 kg of calcium carbonate.

[0068] In the sodium sulfate decalcification process, the total calcium removal rate is 85% for sodium sulfate and 15% for sodium carbonate.

[0069] 3) Carbon emissions include: carbon emissions from the production of calcium removal agents, carbon emissions from electricity consumption during calcium removal operations, and carbon emissions from the use of cement kilns. Sodium sulfate is prepared using the vacuum evaporation method of Glauber's salt for carbon emission calculation, and sodium carbonate is prepared using the ammonia-soda method for carbon emission calculation.

[0070] 4) The national average emission factor of the power grid in 2022 was 0.5703 tCO2 / MWh, and the carbon dioxide emission per unit of purchased steam was 305.14 kgCO2 / t steam.

[0071] The carbon emission factor of sodium sulfate is 0.228tCO2 / tsodium sulfate.

[0072] Carbon emission factor for sodium carbonate preparation: 1.05 tCO2 / t sodium carbonate.

[0073] Based on an annual fly ash processing capacity of 80,000 tons, the amount of calcium ions that need to be removed is 80,000 * 54 / 1,000 = 4,320 tons.

[0074] 5) Carbon emissions from calcium removal agents:

[0075] The sodium sulfate + sodium carbonate process involves the following dosages: 4320 * 3.55 * 0.15 = 13035.6 t; and 4320 * 2.65 * 0.15 = 1717.2 t.

[0076] The carbon emissions of sodium sulfate are: 15336 * 0.228 = 2977.51 t; the carbon emissions of sodium carbonate are: 1717.2 * 1.05 = 1803.6 t.

[0077] Sodium carbonate process: The amount of sodium carbonate added is 4320 * 2.65 = 11448 t. The carbon emissions of the sodium carbonate reagent are 11448 * 1.05 = 12020.4 t.

[0078] 6) The energy consumption and carbon emissions from calcium removal using sodium sulfate and sodium carbonate are:

[0079] The electricity consumption per ton of fly ash in the sodium sulfate dosing system is 200 kWh / fly ash. Therefore, the electricity consumption and emissions required for sodium sulfate to remove calcium are: 80000*200*0.5703 / 1000=9124.8t.

[0080] The electricity consumption per ton of fly ash in the sodium carbonate dosing system is 180 kWh / fly ash. Therefore, the electricity consumption and emissions required for sodium carbonate to remove calcium are: 80000*180*0.5703 / 1000=8212.32t.

[0081] 7) Carbon emissions from subsequent cement kilns:

[0082] The "calcium sulfate + sodium carbonate" process: 15% calcium ion removal uses sodium carbonate, resulting in carbon dioxide emissions of 4320*44 / 40*0.15 = 712.8 tCO2. The sodium carbonate process: high-temperature decomposition generates carbon dioxide, resulting in carbon dioxide emissions of 4320*44 / 40 = 4752 tCO2.

[0083] Table 1 Calculation of Carbon Reduction in Fly Ash Washing Wastewater Process Unit

[0084]

[0085] The total carbon reduction was 10,366.55 t / a, with a carbon reduction rate of 41.49%.

[0086] Example 2: Figures 1 to 8 As shown in Example 1, another embodiment of the present invention is as follows:

[0087] The liquid inlet 3 is located at the top of the reaction vessel 1;

[0088] The mixing assembly includes a rotating rod 2, a stirring rod 12, and a power assembly. The rotating rod 2 is rotatably installed inside the reaction vessel 1, and the stirring rod 12 is fixedly installed on the outer wall of the rotating rod 2. The rotation of the rotating rod 2 is controlled by the power assembly.

[0089] One end of the rotating rod 2 extends out of the top of the reaction vessel 1, and the other end extends into the interior of the reaction vessel 1. The rotating rod 2 is controlled to rotate by the power component, which can drive the stirring rod 12 to stir and mix the solution inside the reaction vessel 1.

[0090] The power assembly includes a drive motor 4, a drive wheel 5, and a driven wheel 6. The drive motor 4 is fixedly installed on the top of the reaction vessel 1. The drive wheel 5 is fixedly connected to the output shaft of the drive motor 4. The driven wheel 6 is fixedly installed on the outer wall of the rotating rod 2. The drive wheel 5 and the driven wheel 6 are connected by a belt.

[0091] The start of the drive motor 4 can drive the drive wheel 5 to rotate, which in turn drives the driven wheel 6 to rotate synchronously under the action of the belt. At this time, the rotating rod 2 can be driven to rotate, so that the stirring rod 12 can stir and mix the solution inside the reaction tank 1.

[0092] Inside the reaction vessel 1, a flow guide block 7 is fixedly installed. The top of the flow guide block 7 is open and tilted downwards towards the rotating rod 2. Inside the liquid inlet 3, a filter plate 8 is fixedly installed. The filter plate 8 is located directly above the flow guide block 7. The wastewater after weight removal flows through the filter plate 8 and onto the flow guide block 7.

[0093] The guide block 7 is located below the liquid inlet 3. When the washing wastewater enters the interior of the reaction tank 1 from the liquid inlet 3, it will flow above the guide block 7. The washing wastewater can be transported towards the rotating rod 2 through the inclined opening on the guide block 7, and finally fall into the bottom of the reaction tank 1. The impurities in the washing wastewater can be filtered through the filter plate 8.

[0094] The conveying assembly includes a weighing and dissolving tank 10, a conveying auger 13, a water inlet 11, and a water outlet 9. The weighing and dissolving tank 10 is hollow and fixedly installed inside the reaction tank 1. The rotating rod 2 passes through the weighing and dissolving tank 10. The conveying auger 13 is located inside the weighing and dissolving tank 10 and is fixedly installed on the outer wall of the rotating rod 2. The water inlet 11 is opened on the bottom outer wall of the weighing and dissolving tank 10. The water outlet 9 is set on the top outer wall of the weighing and dissolving tank 10 and is located above the guide block 7.

[0095] The inlet 11 is located below the liquid surface inside the reaction tank 1, allowing the solution inside the reaction tank 1 to enter the inner cavity of the weighing and dissolving tank 10 through the inlet 11. Under the action of the conveying auger 13, the solution can be conveyed upwards and finally discharged from the outlet pipe 9 located at the top, impacting the washing wastewater flowing on the guide block 7. When the rotating rod 2 rotates, it can simultaneously drive the stirring rod 12 and the conveying auger 13 to rotate.

[0096] The solution inside the reaction tank 1 enters the weighing and dissolving tank 10 through the inlet 11, and is discharged from the outlet pipe 9 by the conveying screw 13 to mix with the washing wastewater flowing on the guide block 7.

[0097] The feeding assembly includes a feeding port 22 and a hole 23. The rotating rod 2 has a cavity inside. The feeding port 22 is located at the top of the rotating rod 2 and communicates with the cavity inside. The hole 23 is located on the outer wall of the rotating rod 2. There are multiple holes 23, and all of the multiple holes 23 are located inside the weighing and dissolving tank 10.

[0098] Solid sodium sulfate can be added through the feeding port 22. At this time, due to the setting of the hole 23, the inner cavity of the rotating rod 2 will conduct the solution in the weighing and dissolving tank 10 to the inside of the rotating rod 2, and complete the mixing inside the weighing and dissolving tank 10. Due to the setting of the weighing and dissolving tank 10, the sodium sulfate can be quickly dissolved in a small area. Then the sodium sulfate solution is discharged from the water outlet pipe 9 and directly mixed with the washing wastewater flowing on the guide block 7, further improving the effect of sodium sulfate in removing calcium ions.

[0099] A rotating rod 14 is rotatably mounted on the stirring rod 12, a rotating ring 15 is rotatably mounted on the outer wall of the rotating rod 14, and a stirring blade 16 is fixedly mounted on the outer wall of the rotating ring 15.

[0100] A baffle rod 17 is fixedly installed inside the reaction vessel 1, and multiple baffle rods 17 are provided;

[0101] When the rotating rod 2 drives the stirring rod 12 to rotate, the rotating rod 14 will drive the stirring blade 16 to rotate synchronously. The stirring blade 16 will be blocked by the blocking rod 17, causing the stirring blade 16 to rotate along the axis of the rotating rod 14.

[0102] The rotating rod 14 is vertically mounted on the stirring rod 12. When the stirring rod 12 rotates, it will drive the rotating rod 14 to rotate synchronously along the rotation trajectory of the stirring rod 12. At this time, the stirring blade 16 can change the movement trajectory of the solution when the solution in the reaction tank 1 rotates in the same direction, thereby improving the mixing effect and further improving the calcium ion removal effect.

[0103] When the stirring blade 16 rotates, it will come into contact with the blocking rod 17 installed inside the reaction vessel 1. The blocking rod 17 can block the stirring blade 16 and cause the stirring blade 16 to drive the rotating ring 15 to rotate on the outer wall of the rotating rod 14. This method can avoid water flow impact, which would affect the rotation of the stirring blade 16.

[0104] A first mounting bracket 18 and a second mounting bracket 21 are fixedly installed on the flow guide block 7. A water turbine blade 19 is rotatably installed on the first mounting bracket 18, and a striking plate 20 is elastically installed on the second mounting bracket 21 via a torsion spring.

[0105] When the washing wastewater passes through the inlet 3 and the filter plate 8, the impact force of the water flow drives the water turbine blade 19 to rotate. At this time, the blades of the water turbine blade 19 strike one end of the striking plate 20. Under the action of the torsion spring, the other end of the striking plate 20 will be raised. By releasing the elastic potential energy through the torsion spring, the raised striking plate 20 can be driven to strike the surface of the filter plate 8. Vibration can reduce the clogging of the filter plate 8 mesh and improve the efficiency of water flow.

[0106] Working principle: Solid sodium sulfate is fed into the weighing and dissolving tank 10 through the feeding port 22. The start of the drive motor 4 drives the drive wheel 5 to rotate, which in turn drives the driven wheel 6 to rotate synchronously under the action of the belt. At this time, the rotating rod 2 drives the stirring rod 12 and the conveying auger 13 to rotate synchronously, so that the solution in the weighing and dissolving tank 10 is discharged from the water outlet pipe 9 and impacts the washing wastewater flowing on the guide block 7 for pre-mixing. The stirring rod 12 and stirring blade 16 further improve the effect of sodium sulfate in removing calcium ions inside the reaction tank 1.

[0107] When the washing wastewater passes through the inlet 3 and the filter plate 8, the impact force of the water flow drives the water turbine blade 19 to rotate. At this time, the blades of the water turbine blade 19 strike one end of the striking plate 20. Under the action of the torsion spring, the other end of the striking plate 20 will be raised. By releasing the elastic potential energy through the torsion spring, the raised striking plate 20 can be driven to strike the surface of the filter plate 8. Vibration can reduce the clogging of the filter plate 8 mesh and improve the efficiency of water flow.

[0108] The terms "front," "back," "left," "right," "top," and "bottom" all refer to the figures in the accompanying drawings. Figure 1 Based on the perspective of the observer, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0109] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0110] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-carbon treatment process for municipal solid waste incineration fly ash washing wastewater, characterized in that: A1: the fly ash is washed by a traditional three-stage countercurrent rinsing process to wash out heavy metals in the fly ash into the liquid phase; A2: the washing wastewater is treated by a water treatment process, and ferrous chloride and sodium sulfide are used in the heavy metal removal section for precipitation treatment; A3: the washing wastewater after heavy metal removal is first delivered into the reaction tank (1) through the liquid inlet (3), then sodium sulfate is fed into the weighing medicine barrel (10) through the feeding assembly, and is discharged through the conveying assembly to contact with the washing wastewater in the reaction tank (1), finally the washing wastewater after heavy metal removal is mixed with sodium sulfate through the mixing assembly to remove calcium ions from the washing wastewater; A4: residual calcium ions are removed by sodium carbonate, and the sodium carbonate removal liquid is filtered by a plate and frame filter, then enters an ultrafiltration and nanofiltration membrane system, and the concentrated liquid of the membrane system is returned to the sodium sulfate weighing medicine barrel (10) system for sodium sulfate solution preparation; A5: the fresh water from the membrane system enters an evaporation system, the mother liquor of the evaporation system is first precipitated by diatomite reaction, then enters a raw ash pre-sizing reaction tank for raw ash sizing; the liquid inlet (3) is arranged at the top end of the reaction tank (1); the mixing assembly comprises a rotating shaft (2), a stirring rod (12) and a power assembly, the rotating shaft (2) is rotatably installed in the interior of the reaction tank (1), the stirring rod (12) is fixedly installed on the outer wall of the rotating shaft (2), and the rotation of the rotating shaft (2) is controlled by the power assembly; a flow guide block (7) is fixedly installed in the interior of the reaction tank (1), the top end of the flow guide block (7) is provided with an opening, and the opening is inclined downward toward the position of the rotating shaft (2), a filter plate (8) is fixedly installed in the interior of the liquid inlet (3), the filter plate (8) is arranged directly above the flow guide block (7), and the washing wastewater after heavy metal removal passes through the filter plate (8) and flows onto the flow guide block (7); the conveying assembly comprises a weighing medicine barrel (10), a conveying auger (13), a water inlet (11), an outlet pipe (9), the weighing medicine barrel (10) is hollowly arranged and fixedly installed in the interior of the reaction tank (1), the rotating shaft (2) penetrates through the weighing medicine barrel (10), the conveying auger (13) is located in the interior of the weighing medicine barrel (10) and is fixedly installed on the outer wall of the rotating shaft (2), the water inlet (11) is arranged at the bottom end of the outer wall of the weighing medicine barrel (10), the outlet pipe (9) is arranged at the top end of the outer wall of the weighing medicine barrel (10), and the outlet pipe (9) is located above the flow guide block (7); the solution in the interior of the reaction tank (1) enters the interior of the weighing medicine barrel (10) through the water inlet (11), and the solution is discharged from the outlet pipe (9) through the conveying auger (13) to mix with the washing wastewater flowing on the flow guide block (7). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The feeding assembly comprises a feeding port (22) and holes (23), the inside of the rotating rod (2) is provided with a cavity, the feeding port (22) is arranged at the top end of the rotating rod (2) and communicates with the inside cavity, and the holes (23) are arranged on the outer wall of the rotating rod (2), a plurality of holes (23) are arranged, and the plurality of holes (23) are all located in the weighing medicine barrel (10). The water wheel blade (19) is rotatably arranged on the first mounting frame (18), and the knock plate (20) is elastically arranged on the second mounting frame (21) through a torsional spring.

2. The low-carbon treatment process for waste water from water washing of household waste incineration fly ash according to claim 1, characterized in that: The power assembly comprises a driving motor (4), a driving wheel (5) and a driven wheel (6), the driving motor (4) is fixedly arranged at the top end of the reaction tank (1), the driving wheel (5) is fixedly connected with the output shaft of the driving motor (4), the driven wheel (6) is fixedly arranged on the outer wall of the rotating rod (2), and the driving wheel (5) and the driven wheel (6) are connected through a belt.

3. The low-carbon treatment process for waste water from water washing of household waste incineration fly ash according to claim 2, characterized in that: The rotating rod (14) is rotatably arranged on the stirring rod (12), the rotating ring (15) is rotatably arranged on the outer wall of the rotating rod (14), and the stirring blade (16) is fixedly arranged on the outer wall of the rotating ring (15).

4. The low-carbon treatment process for waste water from water washing of household waste incineration fly ash according to claim 3, characterized in that: The inside of the reaction tank (1) is fixedly provided with a plurality of blocking rods (17). When the rotating rod (2) drives the stirring rod (12) to rotate, the rotating rod (14) drives the stirring blade (16) to rotate synchronously at this time, the blocking rod (17) blocks the stirring blade (16), and the stirring blade (16) rotates along the axis direction of the rotating rod (14).

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