A purification and recovery system for synergistically treating fly ash and waste incineration flue gas

Abstract

The utility model discloses a kind of purification recovery systems of synergic processing fly ash and waste incineration flue gas. It includes flue gas processing unit and fly ash processing unit;Flue gas processing unit includes sequentially connected along flue gas flow direction: low-temperature coal economizer, activated carbon injection device, dust removal device, first stage deacidification reaction tower, second stage deacidification reaction tower;Fly ash processing unit includes: fly ash bunker, pickling reaction tank, first solid-liquid separation device, water washing reaction tank, second solid-liquid separation device;First stage deacidification reaction tower is equipped with hydrochloric acid wastewater collection pool, and the hydrochloric acid wastewater collection pool is connected with pickling reaction tank. Purification recovery system in the application, through the depth synergy of flue gas treatment and fly ash treatment, both realize the efficient purification and waste heat recovery of flue gas, and from source optimization fly ash production amount and component, reduce disposal cost, strengthen heavy metal removal effect, more achieve the recycling of salt resources Value-added, promote the green and sustainable development of waste incineration industry.

Description

Technical Field

[0001] This utility model relates to the field of flue gas purification technology, and in particular to a purification and recovery system for co-processing fly ash and waste incineration flue gas. Background Technology

[0002] Waste incineration is one of the main technical means for reducing and harmlessly treating municipal solid waste, and it is widely used in my country. The flue gas produced by incineration contains pollutants such as sulfur dioxide, hydrogen chloride, particulate matter, and heavy metals, which must be treated by a purification and recovery system to meet emission standards. Currently, the mainstream flue gas purification process in waste-to-energy plants mostly adopts a combination of "semi-dry acid removal + activated carbon injection + dry acid removal + bag filter + induced draft fan," the core of which is to remove acidic pollutants from the flue gas by injecting slaked lime.

[0003] However, existing processes have significant drawbacks in practical applications: First, the fly ash generation rate is high. The fly ash is mainly composed of hydrated lime deacidification products, accounting for more than 50%, and contains a large amount of unreacted excess hydrated lime. The fly ash generation rate is as high as about 3% of the waste fed into the furnace, which increases the pressure of subsequent disposal. Second, fly ash disposal costs are high. Existing fly ash resource utilization technologies (such as cement kiln co-processing, high-temperature melting, high-temperature sintering, and low-temperature thermal decomposition) generally rely on water washing pretreatment. The high-salt wastewater generated during the water washing process contains a large amount of calcium ions, requiring the addition of a large amount of decalcification agents, resulting in poor overall economic efficiency. Third, heavy metal removal is incomplete. Existing fly ash resource utilization processes have failed to effectively solve the problem of heavy metal pollution, and heavy metals still remain in fly ash or treatment products. Therefore, existing methods for purifying flue gas and disposing of fly ash from waste incineration suffer from drawbacks such as high fly ash generation rates, high fly ash disposal costs, and incomplete removal of heavy metals. These shortcomings hinder the green and sustainable development of the waste incineration industry, necessitating the development of a technological solution that can address these issues. Utility Model Content

[0004] This utility model discloses a purification and recovery system for the coordinated treatment of fly ash and waste incineration flue gas, in order to solve the technical problems of high fly ash generation rate, high fly ash disposal cost and incomplete heavy metal removal in the purification and treatment of waste incineration flue gas.

[0005] To solve the above problems, the present invention adopts the following technical solution: This application provides a purification and recovery system for co-processing fly ash and waste incineration flue gas, including a flue gas treatment unit and a fly ash treatment unit; The flue gas treatment unit comprises the following components connected sequentially along the flue gas flow direction: Low-temperature economizer is used to recover waste heat from flue gas; An activated carbon injection device is connected to the flue gas outlet pipe of the low-temperature economizer; The dust removal device is connected to the end of the flue gas outlet pipeline of the low-temperature economizer; A primary acid removal reaction tower is connected to the flue gas outlet of the dust removal device; A secondary acid removal reaction tower is connected to the flue gas outlet of the primary acid removal reaction tower; The fly ash treatment unit includes: Fly ash silo, connected to the fly ash discharge port of the dust removal device; Pickling reaction vessel, connected to the fly ash outlet of fly ash silo; The first solid-liquid separation device is connected to the outlet of the pickling reaction tank; A water-washing reaction tank is connected to the solid phase outlet of the first solid-liquid separation device; The second solid-liquid separation device is connected to the outlet of the water washing reaction tank; The primary deacidification reaction tower is equipped with a hydrochloric acid wastewater collection tank, which is connected to the acid washing reaction tank via a pipeline.

[0006] The technical solution adopted in this utility model can achieve the following beneficial effects: The purification and recovery system for co-processing fly ash and waste incineration flue gas provided in this application achieves efficient purification and waste heat recovery of flue gas through deep synergy between flue gas treatment and fly ash treatment. It also optimizes the amount and composition of fly ash generated at the source, reduces disposal costs, enhances heavy metal removal, and achieves added value through the recovery of salt resources, thus promoting the green and sustainable development of the waste incineration industry. Specifically, it has the following advantages: (1) This application adopts a combination of a primary deacidification reaction tower and a secondary deacidification reaction tower. Through two-stage wet deacidification, it can replace the traditional quicklime injection deacidification, thus avoiding the entry of quicklime deacidification products into fly ash from the source and significantly reducing the fly ash generation rate. At the same time, the fly ash composition is mainly composed of flue gas particulate matter and activated carbon, which greatly reduces the total amount of fly ash and fundamentally alleviates the pressure of subsequent fly ash disposal. Therefore, the purification and recovery system in this application can significantly reduce the amount of fly ash generated and optimize the fly ash composition when purifying the flue gas from waste incineration, thereby alleviating the pressure of subsequent disposal.

[0007] (2) This application utilizes a collaborative model of "flue gas deacidification wastewater - fly ash acid washing" to directly use hydrochloric acid wastewater generated by the primary deacidification reaction tower for fly ash acid washing, eliminating the need for additional acid washing reagents. Simultaneously, due to the significant reduction in calcium salt (derived from slaked lime) content in fly ash, the consumption of decalcification reagents during subsequent water washing and treatment processes is also reduced. Furthermore, the soluble chloride salts (sodium chloride, potassium chloride) separated during fly ash acid washing and water washing can be purified through membrane separation, evaporation crystallization, and other processes in the wastewater treatment unit and sold as products, realizing the transformation of pollutants into resources. Through the dual design of "waste treatment + resource recovery," not only is the reagent cost of fly ash disposal directly reduced, but additional economic benefits are also created, significantly improving the overall economic efficiency.

[0008] (3) The pickling reaction tank set up in this application uses hydrochloric acid wastewater generated by the first-stage deacidification reaction tower to pickle fly ash. Under acidic environment, it can effectively dissolve heavy metals in fly ash in the form of oxides, hydroxides, carbonates, etc., and convert them into soluble substances that enter the pickling waste liquid. Combined with the further treatment of the subsequent water washing reaction tank, it can significantly reduce the residue of heavy metals in fly ash and final treatment products. After subsequent heat treatment in the furnace, it can be directly used as building material.

[0009] (4) In this application, after recovering waste heat from the low-temperature economizer, the activated carbon injection device precisely injects activated carbon to adsorb heavy metals and dioxins in the flue gas. Then, the dust removal device efficiently captures particulate matter. Subsequently, hydrogen chloride is removed by water spraying in the primary deacidification reaction tower, and sulfur dioxide is removed by alkaline spraying in the secondary deacidification reaction tower, forming a multi-stage synergistic purification system. The links are closely connected and highly targeted, which can comprehensively remove acidic pollutants, particulate matter, heavy metals and persistent organic pollutants in the flue gas, ensuring that the purified flue gas indicators are stable and meet the strict environmental emission requirements, demonstrating a highly efficient flue gas treatment capability.

[0010] (5) In this application, a low-temperature economizer is installed at the front end of the flue gas treatment, which can recover the waste heat of the flue gas entering the subsequent purification stage, convert the originally idle flue gas heat energy into usable energy, reduce energy loss, and improve the energy utilization efficiency of the entire system. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a connection diagram of an embodiment of this application.

[0013] In the diagram: 1. Low-temperature economizer; 2. Flue gas inlet pipe; 3. Dust removal device; 4. Primary deacidification reaction tower; 5. Secondary deacidification reaction tower; 6. Fly ash silo; 7. Acid washing reaction tank; 8. First fly ash conveying system; 9. Second fly ash conveying system; 10. First solid-liquid separation device; 11. Second solid-liquid separation device; 12. Water washing reaction tank; 13. Activated carbon silo; 14. Activated carbon injection pipeline; 15. Jet blower; 16. Clear liquid pump; 17. Hydrochloric acid wastewater collection tank; 18. Second return liquid pipe; 19. Evaporation crystallization device; 20. pH online monitoring instrument; 21. First return liquid pipe; 22. First control valve; 23. Acid pump; 24. First pH sensor; 5. Water tank; 26. First water pump; 27. Second water pump; 28. Alkali tank; 29. ​​First alkali pump; 30. Second alkali pump; 31. Chimney; 32. Exhaust fan; 33. First slurry pump; 34. Second slurry pump; 35. Mixing machine; 36. Wastewater collection and treatment tank; 37. Second pH sensor; 38. Third solid-liquid separation device; 39. Membrane treatment system; 40. Deacidification wastewater collection tank; 41. Temperature sensor; 42. Second control valve; 43. First level switch; 44. Second level switch; 45. First level indicator; 46. Second level indicator; 47. Delivery pump; 48. Delivery pipeline; 49. Alkali pipeline; 50. Curing room. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0015] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0016] like Figure 1 As shown: This application provides a purification and recovery system for co-processing fly ash and waste incineration flue gas, including a flue gas treatment unit and a fly ash treatment unit; The flue gas treatment unit comprises the following components connected sequentially along the flue gas flow direction: Low-temperature economizer 1: Flue gas from the boiler enters the low-temperature economizer 1 through the flue gas inlet pipe 2, and waste heat of the flue gas is recovered through the low-temperature economizer 1. An activated carbon injection device is connected to the flue gas outlet pipe of the low-temperature economizer 1; the activated carbon injected by the activated carbon injection device is used to adsorb heavy metals and dioxin pollutants in the flue gas. Dust removal device 3 is connected to the end of the flue gas outlet pipe of low-temperature economizer 1; dust removal device 3 is used to collect particulate matter in flue gas, which includes particulate matter in the flue gas itself and activated carbon particles. The primary acid removal reaction tower 4 is connected to the flue gas outlet of the dust removal device 3; the primary acid removal reaction tower 4 uses water spraying to remove hydrogen chloride from the flue gas. The secondary acid removal reaction tower 5 is connected to the flue gas outlet of the primary acid removal reaction tower 4; the secondary acid removal reaction tower 5 uses alkaline solution (such as sodium hydroxide solution) spray to remove sulfur dioxide from the flue gas; thus, purified flue gas can be obtained and can be directly discharged into the external environment; The fly ash treatment unit includes: The fly ash silo 6 is connected to the fly ash outlet of the dust removal device 3. The fly ash is transported from the fly ash outlet of the dust removal device 3 to the fly ash silo 6 through a closed pipeline via the first fly ash conveying system 8. Pickling reaction tank 7 is connected to the fly ash outlet of fly ash silo 6 via a closed pipeline. Pickling reaction tank 7 is used for pickling fly ash. Residual heavy metals (such as Pb, Cd, Cr, Zn, etc.) in the fly ash exist mainly in the form of oxides, hydroxides, and carbonates, which dissolve under strongly acidic conditions. The resulting soluble heavy metal chlorides (such as PbCl2, CdCl2, etc.) enter the pickling waste liquid, thus removing heavy metals from the fly ash. Simultaneously, during the pickling of fly ash, any soluble chlorides (such as NaCl, KCl, etc.) that may be present in the fly ash dissolve directly in water without additional reaction and are separated with the pickling waste liquid. The first solid-liquid separation device 10 is connected to the discharge port of the pickling reaction tank 7; it is used to separate fly ash and pickling waste liquid after pickling. The water washing reaction tank 12 is connected to the solid phase outlet of the first solid-liquid separation device 10; The second solid-liquid separation device 11 is connected to the discharge port of the water washing reaction tank 12; it is used to separate fly ash and water washing waste liquid after water washing. The primary deacidification reaction tower 4 is equipped with a hydrochloric acid wastewater collection tank 17, which is connected to the pickling reaction tank 7 through a pipeline. The collected hydrochloric acid wastewater is used for pickling fly ash to achieve waste treatment and resource utilization of hydrochloric acid wastewater.

[0017] In some embodiments, the activated carbon injection device includes an activated carbon chamber 13 and an activated carbon injection pipeline 14 connected to the activated carbon chamber 13. An injection fan 15 is connected to the activated carbon injection pipeline 14, and the end of the activated carbon injection pipeline 14 is connected to the flue gas outlet pipeline of the low-temperature economizer 1. It is understood that by precisely delivering activated carbon to the flue gas outlet pipeline of the low-temperature economizer 1 through the injection fan 15, the activated carbon can be fully mixed and contacted with the flue gas before it enters subsequent treatment stages, enhancing the adsorption effect on pollutants such as heavy metals and dioxins in the flue gas. This design, which sets the injection point at the flue gas outlet of the low-temperature economizer 1, can utilize the appropriate flue gas temperature to enhance the activity of the activated carbon while avoiding the impact of high temperature on the adsorption performance of the activated carbon, ensuring adsorption efficiency and reducing the pollutant treatment pressure for subsequent purification processes.

[0018] In some embodiments, the jet blower 15 is a Roots blower, and there is at least one jet blower 15. It is understood that providing at least one jet blower 15, with the number selectable as needed, can flexibly adapt to the treatment requirements of different flue gas volumes and pollutant concentrations. Furthermore, a backup jet blower 15 can be configured, allowing for rapid switching in case of a failure of the main jet blower 15, preventing interruption of activated carbon injection due to equipment shutdown, ensuring the continuity and stability of the flue gas purification process, and reducing system operational risks.

[0019] In some embodiments, the purification and recovery system further includes a water tank 25 and an alkali tank 28; the water tank 25 is connected to a spray pipeline in the primary deacidification tower via a liquid delivery pipeline 48, and a first water pump 26 is connected to the liquid delivery pipeline 48 for pumping the liquid in the water tank 25. The alkali tank 28 is connected to the spray pipeline in the secondary deacidification tower via the alkali pipeline 49. The alkali pipeline 49 is equipped with a first alkali pump 29 for pumping alkali.

[0020] In some embodiments, a second water pump 27 is also included, which is connected in parallel with the first water pump 26 on the liquid delivery line 48; a second alkali pump 30 is also included, which is connected in parallel with the first alkali pump 29 on the alkali line 49; both the second water pump 27 and the second alkali pump 30 can be used as standby pumps.

[0021] In some embodiments, a pH online monitoring instrument 20 is connected to the outlet pipe of the primary deacidification reaction tower 4; the purification and recovery system further includes a hydrochloric acid wastewater circulation pipeline, which includes: The first return pipe 21 has its inlet end connected to the outlet pipe of the first-stage deacidification reaction tower 4 and connected to the outlet meter of the pH online monitor 20. The outlet end of the first return pipe 21 is connected to the first-stage deacidification reaction tower 4. The first control valve 22 is connected to the first return pipe 21; The second control valve 42 is connected to the liquid outlet pipeline of the first-stage deacidification reaction tower 4.

[0022] The first control valve 22 and the second control valve 42 are used to control the hydrochloric acid wastewater to be reused for further spraying into the primary deacidification reaction tower 4 or into the hydrochloric acid wastewater collection tank 17 according to the pH value of the hydrochloric acid wastewater monitored by the pH online monitoring instrument 20. It is understandable that by installing an online pH monitor 20 on the outlet pipe of the primary deacidification reaction tower 4, and constructing a linkage control mechanism through the first return pipe 21, the first control valve 22, and the second control valve 42 of the hydrochloric acid wastewater circulation pipeline, the precise diversion and recycling of hydrochloric acid wastewater can be achieved: the online pH monitor 20 monitors the pH of the hydrochloric acid wastewater in real time (indirectly monitoring the concentration of the hydrochloric acid wastewater). When the pH (concentration) of the hydrochloric acid wastewater meets the spraying requirements, the first control valve 22 is opened and the second control valve 42 is closed, allowing the hydrochloric acid wastewater to flow back to the primary deacidification reaction tower 4 through the first return pipe 21 for reuse in spraying, thus realizing resource recycling; when the pH (concentration) of the hydrochloric acid wastewater reaches the discharge conditions, the control valve states are switched, the first control valve 22 is closed and the second control valve 42 is opened, allowing the hydrochloric acid wastewater to enter the hydrochloric acid wastewater collection tank 17, ensuring the acid supply for subsequent fly ash pickling. This design not only improves the utilization rate of water resources and acid solution through recycling, but also ensures the synergistic matching of spray deacidification efficiency and fly ash acid washing effect through the linkage control of pH online monitoring instrument 20. At the same time, it avoids the lag of manual control and enhances the stability and economy of the operation of the first-stage deacidification reaction tower 4.

[0023] In some embodiments, the pH online monitoring instrument 20 is replaced with a conductivity meter and / or an online titration analyzer. It is understood that the pH online monitoring instrument 20 is used to monitor the concentration of hydrochloric acid wastewater. When it is replaced with a conductivity meter and / or an online titration analyzer, the concentration of hydrochloric acid wastewater can be monitored separately using either the conductivity meter or the online titration analyzer, or the conductivity meter and the online titration analyzer can be used in combination. When used in combination, the conductivity meter is used for real-time monitoring, and the online titration analyzer is used for intermittent calibration and verification, which can effectively balance the timeliness and accuracy of monitoring.

[0024] In some embodiments, an acid pump 23 is also connected to the first return pipe 21.

[0025] In some embodiments, the purification and recovery system further includes a chimney 31 connected to the end of the flue gas outlet pipe of the secondary deacidification reaction tower 5, and an induced draft fan 32 is connected to the flue gas outlet pipe of the secondary deacidification reaction tower 5; the purified flue gas can be discharged to the external environment through the chimney 31.

[0026] In some embodiments, a first slurry pump 33 is provided on the connecting pipe between the pickling reaction tank 7 and the first solid-liquid separation device 10; a second slurry pump 34 is connected on the connecting pipe between the water washing reaction tank 12 and the second solid-liquid separation device 11.

[0027] In some embodiments, the purification and recovery system further includes a mixer 35 for treating fly ash after water washing and a second fly ash conveying system 9; the mixer 35 is connected to the solid phase outlet of the second solid-liquid separation device 11; the second fly ash conveying system 9 is connected to the discharge port of the mixer 35. It is understood that after the fly ash undergoes acid washing and water washing, the resulting water-washed filter cake is mixed with cement in the mixer 35, bagged, and then sent to the curing chamber 50 via the second fly ash conveying system 9 for curing. After curing, it is mixed with fresh waste and incinerated in a grate furnace. The ash residue obtained after grate furnace incineration can be directly used as building material.

[0028] In some embodiments, the first solid-liquid separation device 10 includes any one of a plate and frame filter press, a horizontal screw centrifuge, and a vacuum filter.

[0029] In some embodiments, the second solid-liquid separation device 11 includes any one of a plate and frame filter press, a horizontal screw centrifuge, and a vacuum filter.

[0030] In some embodiments, the dust removal device 3 is a bag filter or an electrostatic precipitator.

[0031] In some implementations, the filter bags of the baghouse dust collector are made of PTFE-coated fiberglass. It is understood that PTFE-coated fiberglass combines high-temperature resistance, chemical corrosion resistance, and a smooth surface, making it suitable for the complex operating conditions of high-temperature and corrosive components in waste incineration flue gas. Furthermore, the membrane structure enhances the retention efficiency of fine particulate matter, reducing particulate escape. Simultaneously, the smooth surface reduces fly ash adhesion, facilitates dust removal, ensures long-term stable operation of the dust collector, and provides a clean flue gas environment for subsequent spray desulfurization units.

[0032] In some embodiments, the pickling reaction tank 7 is equipped with a first pH sensor 24. It is understood that the first pH sensor 24 can monitor the pH changes during the fly ash pickling process in real time, providing accurate parameter data for the pickling reaction. This facilitates timely adjustment of the acid addition amount or reaction conditions, controlling the pH during the fly ash pickling process, ensuring efficient removal of heavy metals and soluble chlorides from the fly ash, and preventing the pickling effect from being affected by excessively high or low acidity, thus improving the stability and reliability of fly ash treatment.

[0033] In some embodiments, a temperature sensor 41 is provided at the flue gas outlet of the low-temperature economizer 1. It is understood that the temperature sensor 41 can monitor the temperature of the flue gas after treatment by the low-temperature economizer 1 in real time, providing data support for adjusting the flue gas waste heat recovery efficiency, ensuring that the flue gas temperature is within the suitable operating range of the subsequent activated carbon injection device, avoiding the impact of excessively high temperature on the adsorption performance of activated carbon on pollutants, and ensuring the stable operation of the entire flue gas treatment system.

[0034] In some embodiments, the purification and recycling system further includes a wastewater treatment unit, which comprises, in sequence: Wastewater collection and treatment pond 36 is used to collect wastewater from fly ash pickling and fly ash washing treatment, and the collected wastewater is sequentially treated for heavy metal removal and decalcification and magnesium removal. The third solid-liquid separation device 38 is connected to the outlet of the wastewater collection and treatment tank 36 and is used to initially separate suspended solids and dissolved solids in the wastewater. Membrane treatment system 39 is connected to the liquid phase outlet of the third solid-liquid separation device 38 and is used to further remove organic matter, heavy metals and trace impurities from wastewater. Evaporation crystallization device 19 is connected to the freshwater outlet of membrane treatment system 39; The secondary deacidification reaction tower 5 is equipped with a deacidification waste liquid collection tank 40, which is connected to the wastewater collection and treatment tank 36 through a pipeline. A liquid delivery pump 47 is connected to the pipeline. The collected deacidification waste liquid can be used to treat the wastewater for calcium and magnesium removal, thereby realizing the reuse of the deacidification waste liquid. The evaporation crystallization device 19 is connected to the water washing reaction tank 12 via the second return liquid pipe 18, and is used to reuse the condensate for the water washing of fly ash. It is understood that the wastewater collection and treatment tank 36 not only centrally collects wastewater generated from fly ash acid washing and water washing, but also performs heavy metal removal and decalcification / magnesium removal within the wastewater collection and treatment tank 36. The removal of heavy metals from the wastewater is first completed within the wastewater collection and treatment tank 36, reducing the pressure on subsequent treatment from the source. Furthermore, it innovatively introduces the deacidification waste liquid from the secondary deacidification reaction tower 5, which can be directly used for decalcification / magnesium removal of the wastewater. This adopts a waste-to-waste approach, realizing the resource utilization of the deacidification waste liquid and reducing the consumption of additional decalcification / magnesium removal agents. The third solid-liquid separation device 38 performs preliminary separation on the pretreated wastewater, removing suspended solids and some dissolved substances, providing suitable feed for the membrane treatment system 39. The membrane treatment system 39 further purifies the wastewater, efficiently removing organic matter, residual heavy metals, and trace impurities, ensuring effluent quality. The evaporation crystallization device 19 recovers water resources and salts (sodium chloride, potassium chloride), achieving closed-loop wastewater treatment. Furthermore, the condensate from the evaporation crystallization device 19 is reused in fly ash washing via the second return pipe 18, further improving the system's water circulation loop. The condensate from the evaporation crystallization device 19 directly participates in the fly ash washing process as a clean water source, reducing the need for external fresh water and lowering water consumption. This application enables efficient reuse of condensate in wastewater treatment, linking it with the material cycle of "deacidification waste liquid - wastewater treatment," strengthening the system's resource self-sufficiency, improving wastewater treatment efficiency while reducing operating costs, balancing environmental protection and economy, and forming a synergistic closed-loop treatment process.

[0035] In some embodiments, a clean liquid pump 16 is connected to the second return pipe 18.

[0036] In some embodiments, the membrane treatment system 39 is a nanofiltration system; Alternatively, the membrane treatment system 39 may be an ultrafiltration system; Alternatively, the membrane treatment system 39 may be a combination of an ultrafiltration system and a nanofiltration system. It is understood that a nanofiltration system alone can precisely remove small-molecule organic matter and multivalent ions from wastewater while retaining some monovalent ions; an ultrafiltration system alone excels at removing suspended solids, colloids, and large-molecule impurities from water; and the combination of ultrafiltration and nanofiltration allows for a progressive treatment process of "removing impurities first, then fine filtration." Ultrafiltration first removes large-particle impurities to prevent them from clogging the nanofiltration membrane pores and extending the nanofiltration membrane's lifespan. Nanofiltration then further removes small-molecule pollutants and specific ions, ultimately obtaining higher-purity effluent. The overall treatment effect is more stable, the purification efficiency is better, and it provides high-quality feed for the subsequent evaporation and crystallization unit 19, ensuring the purity of the recovered water and salts and improving the feasibility and stability of resource utilization.

[0037] In some embodiments, the third solid-liquid separation device 38 is a precision filter. It is understood that a precision filter can effectively trap fine suspended solids, colloids, and other particulate impurities in wastewater, preventing them from entering the subsequent membrane treatment system 39 and causing membrane fouling or clogging, thus extending the service life of the membrane module and reducing maintenance costs. Simultaneously, its pretreatment function can improve the quality of the influent to the membrane treatment system 39, ensuring deep purification efficiency and providing fundamental support for the stable operation of the entire wastewater treatment unit.

[0038] In some embodiments, a second pH sensor 37 is installed in the wastewater collection and treatment tank 36. It is understood that pickling wastewater and washing wastewater are collected in the wastewater collection and treatment tank 36, where heavy metals and calcium / magnesium ions are removed sequentially. Before these removal processes, an alkaline solution (such as sodium hydroxide or calcium hydroxide) needs to be added to the wastewater collection and treatment tank 36 to adjust the pH value to 8-9, creating a suitable alkaline environment for the subsequent precipitation reaction of heavy metals and calcium / magnesium ions. Therefore, the second pH sensor 37 can monitor the acidity or alkalinity of the wastewater in the wastewater collection and treatment tank 36 in real time after it enters the tank. By promptly monitoring pH changes, the dosage of treatment agents can be adjusted in advance, avoiding the impact of abnormal acidity or alkalinity on the removal of heavy metals and calcium / magnesium ions, thus ensuring the stable operation and treatment effect of the wastewater treatment unit.

[0039] In some embodiments, the water washing reaction tank 12 includes a single-stage water washing treatment device or a multi-stage water washing treatment device. It is understood that the purpose of setting up a single-stage or multi-stage water washing treatment device is to remove soluble chloride salts from the acid washing cake, as long as the soluble chloride salt content in the washed cake is ultimately reduced to below 1%. Therefore, the number of water washing stages can be flexibly adjusted according to the initial chloride salt content in the fly ash, ensuring that the desalination effect meets the standards while avoiding water waste caused by excessive washing, improving the accuracy and economy of fly ash treatment, and creating favorable conditions for the subsequent resource utilization of fly ash.

[0040] In some implementations, the first fly ash conveying system 8 employs a scraper conveyor.

[0041] In some implementations, the second fly ash conveying system 9 employs a belt conveyor.

[0042] In some embodiments, the pickling reaction tank 7 is further equipped with a first level switch 43 and a first level indicator 45; the water washing pickling reaction tank 7 is further equipped with a second level switch 44 and a second level indicator 46. It is understood that by setting the first level switch 43 and the first level indicator 45 on the pickling reaction tank 7, and the second level switch 44 and the second level indicator 46 on the water washing reaction tank 12, dual monitoring and control of the liquid levels in both reaction tanks can be achieved. The level indicator can display the liquid level height in the tank in real time, providing operators with a clear reference for the liquid level status; the level switch can trigger a switch signal when the liquid level reaches the preset upper or lower limit, used to control the start and stop of the liquid inlet and outlet equipment, avoiding overflow due to excessively high liquid levels or affecting the reaction effect due to excessively low liquid levels. The combination of these two features ensures the stability of the liquid level in the reaction tanks, ensuring that the pickling and water washing reactions are carried out under suitable liquid level conditions, and also reduces manual intervention through automatic interlocking control, improving the safety and stability of the fly ash treatment process.

[0043] In some embodiments, the purification and recycling system further includes a control device; The low-temperature economizer 1, activated carbon injection device, primary deacidification reaction tower 4, secondary deacidification reaction tower 5, acid washing reaction tank 7, first solid-liquid separation device 10, water washing reaction tank 12, second solid-liquid separation device 11, third solid-liquid separation device 38, membrane treatment system 39, evaporation crystallization device 19, temperature sensor 41, first pH sensor 24, second pH sensor 37, pH online monitoring instrument 20, first control valve 22, second control valve 42, jet blower 15, first water pump 26, second water pump 27, first alkali pump 29, second alkali pump 30, induced draft fan 32, first slurry pump 33, second slurry pump 34, mixer 35, clear liquid pump 16, first fly ash conveying system 8, second fly ash conveying system 9, liquid delivery pump 47, first liquid level switch 43, first liquid level indicator 45, second liquid level switch 44 and second liquid level indicator 46 are respectively electrically connected to the control device. Understandably, by setting up a control device and electrically connecting all key equipment, sensors, and actuators (such as various reaction towers, separation devices, pumps, fans, and sensors) in the system to the control device, an intelligent centralized control system for the entire system is constructed. The control device can receive various monitoring data such as temperature and pH value in real time, and automatically adjust the operating parameters of each device according to preset logic, such as adjusting the activated carbon injection volume of the jet fan 15 and switching the opening and closing states of the first control valve 22 and the second control valve 42. This design realizes the linkage and coordination of each link, reduces the intervention of manual operation, not only improves the accuracy and stability of system operation, but also can quickly respond and adjust according to changes in operating conditions, ensuring the optimization of pollutant removal efficiency and resource recovery effect, while reducing the risk of human operation error, providing intelligent guarantee for the efficient and stable operation of the entire purification and recovery system, and further enhancing resource recovery efficiency and pollutant removal effect through real-time parameter optimization.

[0044] In some implementations, the control device is a PLC.

[0045] The working process of the purification and recovery system for co-processing fly ash and waste incineration flue gas in this application is as follows: S1. Flue gas pretreatment and waste heat recovery: Flue gas from the boiler enters the low-temperature economizer 1 through the flue gas inlet pipe 2. The low-temperature economizer 1 recovers the waste heat of the flue gas. The temperature sensor 41 at the flue gas outlet monitors the flue gas temperature in real time to ensure that the temperature is within the appropriate range for subsequent treatment. S2. Activated carbon adsorbs pollutants: The flue gas treated by the low-temperature economizer 1 enters its outlet pipeline. The activated carbon injection device uses the injection fan 15 to accurately inject the activated carbon in the activated carbon bin 13 into the flue gas through the injection pipeline. The activated carbon adsorbs heavy metals and dioxin pollutants in the flue gas. S3. Flue gas dust removal and fly ash collection: The adsorbed flue gas enters the dust removal device 3 (bag dust collector or electrostatic precipitator) to capture particulate matter (including native particulate matter and activated carbon particles) in the flue gas. The resulting fly ash is transported to the fly ash silo 6 for temporary storage through the first fly ash conveying system 8 (scraper conveyor) via a closed pipeline. S4. Primary Deacidification and Hydrochloric Acid Wastewater Circulation: The flue gas after dust removal enters the primary deacidification reaction tower 4. It is sprayed with water supplied by the first water pump 26 (or the backup second water pump 27) through the water tank 25 to remove hydrogen chloride from the flue gas. The generated hydrochloric acid wastewater is transported through the outlet pipeline. The pH (concentration) of the hydrochloric acid wastewater is monitored in real time by the pH online monitoring instrument 20. If the pH (concentration) of the hydrochloric acid wastewater meets the spraying requirements, the first control valve 22 is opened and the second control valve 42 is closed. The wastewater flows back to the primary deacidification reaction tower 4 for circulating spraying through the first return pipe 21. If the pH (concentration) of the hydrochloric acid wastewater reaches the acid washing requirements, the control valve status is switched. The first control valve 22 is closed and the second control valve 42 is opened. The hydrochloric acid wastewater enters the hydrochloric acid wastewater collection tank 17. S5. Secondary Deacidification and Flue Gas Emission: The flue gas from the primary deacidification stage enters the secondary deacidification reaction tower 5. The sulfur dioxide in the flue gas is removed by spraying alkaline solution supplied by the first alkaline solution pump 29 (or the backup second alkaline solution pump 30) into the alkaline solution tank 28. The purified flue gas is discharged to the external environment through the chimney 31 under the action of the induced draft fan 32. The deacidification waste liquid generated by the secondary deacidification stage is collected in the deacidification waste liquid collection tank 40. S6. Fly ash pickling treatment: Fly ash in fly ash silo 6 enters pickling reaction tank 7 through a closed pipeline. Hydrochloric acid wastewater in hydrochloric acid wastewater collection tank 17 is introduced into pickling reaction tank 7. The first pH sensor 24 monitors the pH value in real time during the pickling process to ensure efficient removal of heavy metals and soluble chloride salts from fly ash. The first liquid level switch 43 and the first liquid level indicator 45 of pickling reaction tank 7 work together to control the liquid level stability. S7. Solid-liquid separation after pickling: The mixture after pickling is transported to the first solid-liquid separation device 10 by the first slurry pump 33 to separate the pickling waste liquid and solid phase (pickling mud cake). S8. Fly ash washing treatment: The pickled mud cake enters the washing reaction tank 12 and removes residual soluble chloride salts through one or more stages of washing. The second liquid level switch 44 and the second liquid level indicator 46 of the washing reaction tank 12 work together to control the liquid level stability. S9. Solid-liquid separation and fly ash resource utilization after water washing: The mixture after water washing is transported to the second solid-liquid separation device 11 by the second slurry pump 34 to separate the water washing waste liquid and solid phase (water washing mud cake); the water washing mud cake enters the mixer 35 to mix with cement, and then is sent to the curing room 50 for curing by the second fly ash conveying system 9 (belt conveyor). After curing, it is mixed with fresh garbage and incinerated, and the ash residue is used as building material. S10. Centralized wastewater treatment: Pickling waste liquid and washing waste liquid enter the wastewater collection and treatment tank 36. Under the monitoring of the second pH sensor 37, heavy metal removal and calcium and magnesium removal are completed in sequence. The deacidification waste liquid of the secondary deacidification reaction tower 5 is introduced into the tank by the liquid delivery pump 47 for calcium and magnesium removal. S11. Deep purification of wastewater: The pretreated wastewater enters the third solid-liquid separation device 38 (precision filter) to remove suspended solids and some dissolved solids. The liquid phase enters the membrane treatment system 39 (ultrafiltration, nanofiltration or a combination of both) to further remove organic matter, residual heavy metals and trace impurities. The retained soluble salts (sodium chloride, potassium chloride) enter the subsequent treatment stage. S12. Water Resources and Salt Recovery and Recycling: The fresh water after membrane treatment enters the evaporation crystallization device 19, and the salts (sodium chloride and potassium chloride) are recovered through evaporation crystallization. The generated condensate is returned to the water washing reaction tank 12 via the second return liquid pipe 18 (transported by the clear liquid pump 16), realizing the synergistic recovery and closed-loop utilization of water resources and salts. Throughout the process, the control device (PLC) receives signals from various sensors in real time and coordinates the operating parameters of each device to ensure stable and coordinated operation of the system.

[0046] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0047] Furthermore, it should be noted that the scope of the methods and apparatus in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0048] The above description is only a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model.

Claims

1. A purification and recovery system for co-processing fly ash and waste incineration flue gas, characterized in that, Includes flue gas treatment unit and fly ash treatment unit; The flue gas treatment unit comprises the following components connected sequentially along the flue gas flow direction: Low-temperature economizer is used to recover waste heat from flue gas; An activated carbon injection device is connected to the flue gas outlet pipe of the low-temperature economizer; The dust removal device is connected to the end of the flue gas outlet pipeline of the low-temperature economizer; A primary acid removal reaction tower is connected to the flue gas outlet of the dust removal device; A secondary acid removal reaction tower is connected to the flue gas outlet of the primary acid removal reaction tower; The fly ash treatment unit includes: Fly ash silo, connected to the fly ash discharge port of the dust removal device; Pickling reaction vessel, connected to the fly ash outlet of fly ash silo; The first solid-liquid separation device is connected to the outlet of the pickling reaction tank; A water-washing reaction tank is connected to the solid phase outlet of the first solid-liquid separation device; The second solid-liquid separation device is connected to the outlet of the water washing reaction tank; The primary deacidification reaction tower is equipped with a hydrochloric acid wastewater collection tank, which is connected to the acid washing reaction tank via a pipeline.

2. The purification and recovery system for co-processing fly ash and waste incineration flue gas according to claim 1, characterized in that, A pH online monitoring instrument is connected to the effluent pipeline of the primary deacidification reaction tower; the purification and recovery system also includes a hydrochloric acid wastewater circulation pipeline, which includes: The first return pipe has its inlet end connected to the outlet pipe of the first-stage deacidification reaction tower and is also connected to the outlet measurement of the pH online monitoring instrument. The first control valve is connected to the first return pipe; The second control valve is connected to the liquid outlet pipeline of the first-stage deacidification reaction tower; The first control valve and the second control valve are used to control the hydrochloric acid wastewater to be reused for further spraying or enter the hydrochloric acid wastewater collection tank according to the pH value of the hydrochloric acid wastewater monitored by the pH online monitoring instrument.

3. The purification and recovery system for co-processing fly ash and waste incineration flue gas according to claim 2, characterized in that, The activated carbon injection device includes an activated carbon chamber and an activated carbon injection pipeline connected to the activated carbon chamber. An injection fan is connected to the activated carbon injection pipeline, and the end of the activated carbon injection pipeline is connected to the flue gas outlet pipeline of the low-temperature economizer.

4. The purification and recovery system for co-processing fly ash and waste incineration flue gas according to claim 3, characterized in that, The purification and recovery system also includes a water tank and an alkali tank; the water tank is connected to the spray pipeline in the primary deacidification tower through a liquid delivery pipeline, and a first water pump is connected to the liquid delivery pipeline; the alkali tank is connected to the spray pipeline in the secondary deacidification tower through an alkali pipeline, and a first alkali pump is installed on the alkali pipeline.

5. The purification and recovery system for co-processing fly ash and waste incineration flue gas according to claim 4, characterized in that, The purification and recovery system also includes a chimney connected to the end of the flue gas outlet pipe of the secondary deacidification reaction tower, through which the purified flue gas is discharged to the external environment; an induced draft fan is connected to the flue gas outlet pipe of the secondary deacidification reaction tower. And / or, the purification and recovery system further includes a mixer and a fly ash conveying system for treating fly ash after water washing; the mixer is connected to the solid phase outlet of the second solid-liquid separation device; the fly ash conveying system is connected to the discharge port of the mixer.

6. The purification and recovery system for co-processing fly ash and waste incineration flue gas according to claim 5, characterized in that, The acid washing reaction vessel is equipped with a first pH sensor; And / or, a temperature sensor is installed at the flue gas outlet of the low-temperature economizer.

7. The purification and recovery system for co-processing fly ash and waste incineration flue gas according to claim 6, characterized in that, The dust removal device is a bag filter or an electrostatic precipitator; And / or, the first solid-liquid separation device includes any one of a plate and frame filter press, a horizontal screw centrifuge, and a vacuum filter. And / or, the second solid-liquid separation device includes any one of a plate and frame filter press, a horizontal screw centrifuge, and a vacuum filter.

8. The purification and recovery system for co-processing fly ash and waste incineration flue gas according to claim 7, characterized in that, The purification and recycling system also includes a wastewater treatment unit, which comprises, in sequence: Wastewater collection and treatment pond; The third solid-liquid separation device is connected to the discharge port of the wastewater collection and treatment tank; A membrane treatment system is connected to the liquid phase outlet of the third solid-liquid separation unit; An evaporation crystallization device is connected to the freshwater outlet of a membrane treatment system; The secondary deacidification reaction tower is equipped with a deacidification waste liquid collection tank, which is connected to a wastewater collection and treatment tank through a pipeline. The evaporation crystallization device is connected to the water washing reaction tank through a second return liquid pipe, and a clear liquid pump is connected to the second return liquid pipe.

9. The purification and recovery system for co-processing fly ash and waste incineration flue gas according to claim 8, characterized in that, The membrane treatment system is an ultrafiltration system; And / or, the membrane treatment system is a nanofiltration system; And / or, the membrane treatment system is a combination of an ultrafiltration system and a nanofiltration system; And / or, the third solid-liquid separation device is a precision filter; And / or, a second pH sensor is provided in the wastewater collection and treatment tank.

10. The purification and recovery system for co-processing fly ash and waste incineration flue gas according to claim 9, characterized in that, The purification and recycling system also includes a control device; The low-temperature economizer, activated carbon injection device, primary deacidification reaction tower, secondary deacidification reaction tower, acid washing reaction tank, first solid-liquid separation device, water washing reaction tank, second solid-liquid separation device, third solid-liquid separation device, membrane treatment system, evaporation crystallization device, temperature sensor, first pH sensor, second pH sensor, pH online monitoring instrument, first control valve, second control valve, jet blower, first water pump, second water pump, first alkali pump, second alkali pump, induced draft fan, first slurry pump, second slurry pump, mixer, clear liquid pump, first fly ash conveying system, and second fly ash conveying system are all electrically connected to the control device.

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