Method for co-processing and recycling three wastes in incineration power plant

Abstract

The invention provides a method for co-processing and recycling three wastes of an incineration power plant, and belongs to the technical field of treatment and recycling of the three wastes. According to the method, heavy metals and soluble chlorine salts in the fly ash are eluted by utilizing the leachate, the fly ash is subjected to low-temperature pyrohydrolysis by adopting an anaerobic environment provided by the flue gas, dioxin in the fly ash and the flue gas is degraded, and residual heavy metals and soluble chlorine salts in the fly ash are deeply eluted by utilizing the leachate again; fly ash is subjected to wet mineralization through CO2 in flue gas, heavy metal in eluent is precipitated and separated through the CO2 in the flue gas, and KCl and NaCl in concentrated eluent are recycled through membrane filtration and membrane evaporation technologies. The three-waste landfill leachate generated in the production process of the waste incineration power plant, the household waste incineration fly ash and the flue gas are subjected to collaborative harmless treatment and resource utilization, and the problems of high-salinity wastewater and solid waste resource utilization and flue gas deep decarburization are creatively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of three wastes treatment and resource utilization, and in particular relates to a method for coordinated disposal and resource utilization of three wastes from an incineration power plant. Background Art

[0002] With the improvement of residents' living standards, the output of domestic waste has increased rapidly. Domestic waste incineration technology has been widely promoted in recent years due to its obvious advantages of reduction, stabilization and resource utilization. During the incineration process of domestic waste, power plants will produce solid, liquid and gas wastes such as domestic waste leachate, incineration fly ash and flue gas.

[0003] Since garbage leachate contains high concentrations of ammonia nitrogen, COD, heavy metals, organic matter and other substances, the organic matter such as chlorinated aromatics in the leachate is extremely difficult to biodegrade, and there is also the influence of high concentrations of ammonia nitrogen, resulting in low efficiency of conventional biological methods in destroying pollutants. Although conventional physical and chemical methods can effectively remove heavy metals in leachate, they are expensive and insufficient to remove various organic matters in the leachate at the same time.

[0004] Fly ash from the incineration of domestic waste refers to tiny particles emitted during the incineration process and collected by the terminal dust collector. It is rich in heavy metals and carcinogenic dioxins, and has extremely high leaching toxicity. The main treatment and disposal technologies for fly ash from the incineration of domestic waste include three technical routes: entering hazardous waste landfills after solidification, sanitary landfill after stabilization, and resource utilization. Commonly used solidification and stabilization technologies include cement solidification, melt solidification, and chelation stabilization technology. After stabilization, fly ash enters the landfill for disposal. Most hazardous waste treatment plants charge an entrance fee of more than 1,000 yuan per ton of fly ash. In some areas where disposal sites are scarce, the cost of hazardous waste disposal sites is as high as 3,000 yuan / ton. After strict pretreatment, it enters the domestic waste landfill for disposal, and the treatment cost is as high as 500 to 1,000 yuan / ton, which increases the treatment cost of domestic waste by 80 to 300 yuan / ton. Therefore, developing fly ash resource technology and reducing the cost of fly ash landfill are the current research hotspots and application mainstream development directions of incineration fly ash treatment and disposal technology. Due to differences in production processes, the SiO2 and Al2O3 contents of grate furnace fly ash are generally less than 2%, and it contains a large amount of soluble salts such as NaCl, KCl and CaClOH, which seriously limits its use value as an auxiliary cementitious material for traditional Portland cement and geopolymer cement.

[0005] The flue gas produced by garbage incineration often contains excess carbon dioxide after desulfurization and denitrification treatment. Direct discharge into the atmosphere will accelerate the formation of the greenhouse effect. How to make full use of the carbon dioxide in the flue gas is also a problem that needs to be solved urgently. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a method for coordinated disposal and resource utilization of three wastes in an incineration power plant, so as to realize the coordinated disposal and resource utilization of domestic waste leachate, incineration fly ash and incineration flue gas generated during the incineration process of domestic waste.

[0007] To achieve the above object, the present invention provides a method for the coordinated disposal of three wastes from an incineration power plant, comprising the following steps:

[0008] S1. The waste incineration fly ash and the landfill leachate are passed through a three-stage countercurrent washing device, mixed and reacted, and then solid-liquid separation is performed to obtain preliminary washed fly ash and washing liquid;

[0009] S2. The preliminary washed fly ash obtained in step S1 is introduced into a high temperature and high pressure reactor, and flue gas and landfill leachate are introduced into the high temperature and high pressure reactor, and after low temperature and hot water hydrolysis reaction, centrifugation and solid-liquid separation are performed to obtain mineralized and detoxified fly ash, so as to realize resource utilization;

[0010] S3. The washing liquid obtained by solid-liquid separation in steps S1 and S2 is treated by a nanofiltration membrane to obtain a concentrated solution containing COD and heavy metals and a filtrate;

[0011] S4. The concentrated solution obtained in step S3 and the remaining flue gas in step S2 are passed into a high-pressure reactor, and the metal in the concentrated solution is removed by supercritical CO2 precipitation to form a metal carbonate precipitate. The metal carbonate precipitate is separated by centrifugation and the solid is stably landfilled. The obtained concentrated solution containing COD is sprayed back into the waste incinerator, and the decarbonized flue gas is discharged under reduced pressure;

[0012] S5. The filtrate obtained in step S3 is treated with a reverse osmosis membrane to remove monovalent salts, and the high-salt concentrate enters a high-pressure reverse osmosis and thermal evaporation process, and then industrial salt is obtained by concentration and crystallization. The obtained clear liquid or condensed clear liquid meets the discharge standards.

[0013] Furthermore, the solid-liquid ratio of the waste incineration fly ash to the waste leachate in S1 is 1: (2-10) kg / L.

[0014] Furthermore, the temperature of the mixed reaction in S1 is 25-55° C., the rotation speed is 120-200 rpm, and the pH is 4-5.

[0015] Furthermore, one or more of salicylic acid, citric acid and acetic acid is added to adjust the pH to 4-5.

[0016] Furthermore, the solid-liquid ratio of the preliminary washed fly ash to the landfill leachate in S2 is 1: (2-10) kg / L.

[0017] Furthermore, the temperature of the low-temperature thermal hydrolysis reaction in S2 is 300-400° C., and the reaction time is 2-5 hours.

[0018] Furthermore, the pressure of the high-pressure reactor in S4 is 7.5-8.5 MPa, and the temperature is 31-35°C.

[0019] Furthermore, the waste incineration fly ash is captured by a flue gas purification system during the incineration and disposal of domestic waste.

[0020] Furthermore, the landfill leachate is an acidic liquid produced when domestic waste is piled up for 5 to 7 days before incineration.

[0021] Furthermore, the flue gas is the flue gas that meets the standards and is discharged by a flue gas purification system during the incineration and disposal of domestic waste.

[0022] More specifically, a method for the coordinated disposal of three wastes from an incineration power plant for resource utilization comprises the following steps:

[0023] S1. The waste incineration fly ash and the landfill leachate are passed through a three-stage countercurrent washing device, the solid-liquid ratio of the waste incineration fly ash to the landfill leachate is 1: (2-10) kg / L, at 25-55°C and a rotation speed of 120-200 rpm, one or more of salicylic acid, citric acid and acetic acid are added to adjust the pH to 4-5, the heavy metals and soluble salts in the waste incineration fly ash are separated by the landfill leachate, and the mixed reaction is carried out for 30 minutes to 1 hour, and then solid-liquid separation is performed to obtain preliminary washed fly ash and water washing liquid;

[0024] S2. The preliminary washed fly ash obtained in step S1 is introduced into a high-temperature and high-pressure reactor, and flue gas and landfill leachate are introduced into the high-temperature and high-pressure reactor, the solid-liquid ratio of the preliminary washed fly ash to the landfill leachate is 1: (2-10) kg / L, the temperature is maintained at 300-400°C by using steam waste heat, and the reaction time is maintained for 2-5 hours to degrade dioxins in the flue gas and fly ash, and the CO2 in the flue gas is used to mineralize the fly ash, and after low-temperature hot water hydrolysis reaction, the fly ash and the washing liquid are centrifuged and solid-liquid separated to obtain mineralized and detoxified fly ash, and the washing liquid is used together with the bottom ash for resource utilization;

[0025] S3. The washing liquid obtained by the solid-liquid separation in steps S1 and S2 is treated with a nanofiltration membrane (nanofiltration NF) to remove COD, ammonia nitrogen and heavy metals (HMs) to obtain a concentrated solution containing COD and heavy metals and a filtrate;

[0026] S4. The concentrated solution obtained in step S3 is passed into a high-pressure reactor, the pressure of the high-pressure reactor is 7.5-8.5 MPa, the temperature is 31-35 ° C, the remaining flue gas in step S2 is passed into the high-pressure reactor, under this condition, supercritical CO2 is formed, and the CO2 in the flue gas and the Pb in the concentrated solution are used. 2+ 、Cd 2+ , Cu 2+ 、Zn 2+ Cr 3+ Heavy metals and divalent Ca 2+Mg 2+ The ions form metal carbonate precipitation, which is then centrifuged and then landfilled. The concentrated liquid containing COD is sprayed back into the incinerator to adjust the incineration furnace temperature, slow down coking, and reduce NO in the furnace flue gas. x content, decarbonized flue gas reduced pressure emission;

[0027] S5. The filtrate obtained in step S3 is treated with a reverse osmosis membrane (RO) to remove monovalent salts of NaCl and KCl. The high-salt concentrate enters the high-pressure reverse osmosis DTRO / HPRO and thermal evaporation MVR process, and then KCl and NaCl industrial salts are obtained by concentration and crystallization. The clear liquid or condensed clear liquid obtained by the RO, DTRO / HPRO, MVR, and concentration process meets the discharge standards.

[0028] On the one hand, the present invention utilizes leachate to elute heavy metals and soluble chloride salts in fly ash; on the other hand, the anaerobic environment provided by flue gas and low-temperature thermal hydrolysis of fly ash are used to degrade dioxins in fly ash and flue gas, and the leachate is used again to deeply elute the residual heavy metals and soluble chloride salts in fly ash, and the fly ash is wet-mineralized using CO2 in flue gas; in the third aspect, the present invention utilizes CO2 in flue gas to precipitate and separate heavy metals in the eluate, and uses membrane filtration and membrane evaporation technology to recover KCl and NaCl in the concentrated eluate. The total amount of dioxin residues in the fly ash finally obtained meets the requirements of HJ 1134; the heavy metal leaching concentration meets the national standard of GB 8978, and can be mixed into bottom ash for resource utilization; the leachate is discharged in compliance with the standards, and the concentrated solution is sprayed back into the furnace; the volume fraction of CO2 in the flue gas is reduced to below 2%.

[0029] Compared with the prior art, the present invention has the following advantages and technical effects:

[0030] (1) The present invention treats the three wastes generated in the production process of the waste incineration power plant, namely, landfill leachate, domestic waste incineration fly ash and flue gas, in a coordinated and harmless manner and utilizes them as resources, creatively solving the problems of high-salinity wastewater, solid waste resource utilization and deep decarbonization of flue gas:

[0031] The method of the present invention utilizes the weak acidity of a part of the landfill leachate to perform three-stage countercurrent water washing on the fly ash from the incineration of domestic waste to remove more than 90% of the soluble salts and heavy metals in the fly ash from the domestic waste, and then the remaining leachate, the washed fly ash and the flue gas are subjected to a low-temperature hot water hydrolysis process to further remove the soluble salts and heavy metals in the fly ash, and degrade the dioxins in the fly ash and the flue gas, and utilize part of the CO2 in the flue gas to form mineralized and detoxified fly ash, so that the total amount of dioxin residues in the finally obtained fly ash meets the requirements of HJ 1134; the heavy metal leaching concentration meets the national standard GB 8978, and the fly ash can be mixed into the bottom ash for resource utilization.

[0032] The washing liquid produced by the three-stage countercurrent washing and low-temperature thermal hydrolysis process is rich in COD, ammonia nitrogen, Na + , K + , Cl - , heavy metal ions, and high CO2 content in flue gas. The nanofiltration process is used to separate the clear solution of monovalent salts and the concentrated solution containing high COD and heavy metals. The supercritical CO2 reactor is further used to promote the formation of a supercritical state of CO2 in the flue gas, greatly increasing its solubility in the concentrated solution to more than 30,000 ppm, promoting the removal of heavy metals and Ca in the concentrated solution. 2+ Mg 2+ The ions produce carbonate precipitation, and the COD and ammonia nitrogen concentrate are separated and sprayed back into the incinerator furnace. They enter the incinerator to adjust the incinerator furnace temperature, slow down coking, and reduce NO in the furnace flue gas. x The decarbonized flue gas is discharged under reduced pressure; the reduced carbonate precipitate is stabilized and solidified before landfill. The CO2 volume fraction of the flue gas drops to less than 2% after supercritical CO2 deep decarbonization. The monovalent salt clear liquid after nanofiltration continues to be separated and crystallized by reverse osmosis, high-pressure reverse osmosis, thermal evaporation and concentration processes to obtain separated and crystallized salts NaCl and KCl. The clear liquid is discharged or enters the three-stage countercurrent water washing process and high-temperature thermal hydrolysis process as supplementary water.

[0033] (2) The resource utilization method of the present invention does not require drug consumption, reduces the procurement cost of fly ash treatment chelating agents and leachate treatment flocculants in municipal solid waste incineration plants, and utilizes the flue gas heat energy of the boiler and the electricity generated by incineration power generation, which is clean and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0035] Figure 1 This is a flow chart of the method for coordinated disposal of three wastes from an incineration power plant for resource utilization according to the present invention;

[0036] Figure 2 The XRD mineral composition spectra of the original fly ash, the mineralized and detoxified fly ash in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0041] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0042] The embodiment of the present invention provides a method for the coordinated disposal of three wastes from an incineration power plant (see the flowchart for Figure 1 ), including the following steps:

[0043] S1. The waste incineration fly ash and the landfill leachate are passed through a three-stage countercurrent washing device to separate the heavy metals and soluble salts in the waste incineration fly ash by landfill leachate, and then solid-liquid separation is performed after mixed reaction to obtain preliminary washed fly ash and washing liquid;

[0044] S2. The preliminarily washed fly ash obtained in step S1 is introduced into a high-temperature and high-pressure reactor, and flue gas and landfill leachate are introduced into the high-temperature and high-pressure reactor to degrade dioxins in the flue gas and fly ash, and the fly ash is mineralized by CO2 in the flue gas, and the mineralized and detoxified fly ash is obtained by centrifugation and solid-liquid separation after low-temperature and hot hydrolysis reaction, and is utilized as a resource together with the bottom ash;

[0045] S3. The washing liquid obtained by the solid-liquid separation in steps S1 and S2 is treated with a nanofiltration membrane (nanofiltration NF) to remove COD, ammonia nitrogen and heavy metals (HMs) to obtain a concentrated solution containing COD and heavy metals and a filtrate;

[0046] S4. The concentrated solution obtained in step S3 is passed into a high-pressure reactor, and the remaining flue gas in step S2 is passed into a high-pressure reactor. Under this condition, supercritical CO2 is formed, and the CO2 in the flue gas and the Pb in the concentrated solution are used. 2+ 、Cd 2+ , Cu 2+ 、Zn 2+ Cr 3+ Heavy metals and divalent Ca 2+ Mg 2+ The ions form metal carbonate precipitation, which is then centrifuged and then landfilled. The concentrated liquid containing COD is sprayed back into the incinerator to adjust the incineration furnace temperature, slow down coking, and reduce NO in the furnace flue gas. x content, decarbonized flue gas reduced pressure emission;

[0047] S5. The filtrate obtained in step S3 is treated with a reverse osmosis membrane (RO) to remove monovalent salts of NaCl and KCl. The high-salt concentrate enters the high-pressure reverse osmosis DTRO / HPRO and thermal evaporation MVR process, and then KCl and NaCl industrial salts are obtained through concentration and crystallization. The clear liquid or condensed clear liquid obtained by the RO, DTRO / HPRO, MVR, and concentration process meets the discharge standards.

[0048] In the embodiment of the present invention, the solid-liquid ratio of the waste incineration fly ash to the waste leachate in S1 is 1: (2-10) kg / L.

[0049] In the embodiment of the present invention, the temperature of the mixed reaction in S1 is 25-55° C., the rotation speed is 120-200 rpm, and the pH is 4-5.

[0050] In an embodiment of the present invention, one or more of salicylic acid, citric acid and acetic acid is added to adjust the pH to 4-5.

[0051] In the embodiment of the present invention, the solid-liquid ratio of the preliminary washed fly ash to the landfill leachate in S2 is 1: (2-10) kg / L.

[0052] In the embodiment of the present invention, the temperature of the low-temperature thermal hydrolysis degradation reaction in S2 is 300-400° C., and the reaction time is 2-5 hours.

[0053] In the embodiment of the present invention, the pressure of the high-pressure reactor in S4 is 7.5-8.5 MPa, and the temperature is 31-35°C.

[0054] In an embodiment of the present invention, the waste incineration fly ash is captured by a flue gas purification system during the incineration and disposal of domestic waste.

[0055] In the embodiment of the present invention, the landfill leachate is an acidic liquid generated when domestic waste is piled up for 5 to 7 days before incineration.

[0056] In the embodiment of the present invention, the flue gas is the flue gas that meets the emission standards from the flue gas purification system during the incineration process of domestic waste.

[0057] In the embodiments of the present invention, the three-stage countercurrent water washing device, high temperature and high pressure reactor, reverse osmosis RO process, nanofiltration NF treatment process, high pressure reverse osmosis DTRO / HPRO and thermal evaporation MVR process used are all conventional technical devices and technical means in the field.

[0058] In the embodiment of the present invention, the specific sources of the waste incineration fly ash, landfill leachate and flue gas used are a waste incineration power plant in Wuhan, and the technology used is the grate furnace process. After measurement, the content of characteristic pollutants in the waste incineration fly ash, landfill leachate and flue gas is shown in Table 1.

[0059] Table 1 Characteristic pollutant contents of three wastes in waste incineration power plants

[0060]

[0061] The technical solution of the present invention is further illustrated by the following embodiments.

[0062] Example 1

[0063] A method for the coordinated disposal of three wastes from an incineration power plant for resource utilization comprises the following steps:

[0064] S1. The waste incineration fly ash and the landfill leachate are passed through a three-stage countercurrent washing device (using the three-stage countercurrent washing device for fly ash treatment disclosed in CN114798681A), the solid-liquid ratio of the waste incineration fly ash to the landfill leachate is 1:8 (kg / L), at 35°C and a rotation speed of 180 rpm, salicylic acid is added to adjust the pH to 4, and the heavy metals and soluble salts in the waste incineration fly ash are separated by landfill leachate, and the mixed reaction is carried out for 50 minutes, and then solid-liquid separation is performed to obtain preliminary washed fly ash and washing liquid;

[0065] S2. The preliminary washed fly ash obtained in step S1 is introduced into a high-temperature and high-pressure reactor, and flue gas and landfill leachate are introduced into the high-temperature and high-pressure reactor, the solid-liquid ratio of the preliminary washed fly ash to the landfill leachate is 1:8 (kg / L), the temperature is maintained at 380°C by using steam waste heat, the reaction time is maintained for 3 hours, dioxins in the flue gas and fly ash are degraded, and CO2 in the flue gas is used to mineralize the fly ash, and after low-temperature hot water hydrolysis reaction, the fly ash is centrifuged and solid-liquid separated to obtain mineralized and detoxified fly ash, which is utilized as a resource together with the bottom ash;

[0066] S3. The washing liquid obtained by the solid-liquid separation in steps S1 and S2 is treated with a nanofiltration membrane (nanofiltration NF) to remove COD, ammonia nitrogen and heavy metals (HMs) to obtain a concentrated solution containing COD and heavy metals and a filtrate;

[0067] S4. The concentrated solution obtained in step S3 is passed into a high-pressure reactor at a pressure of 8 MPa and a temperature of 32 ° C. The remaining flue gas in step S2 is passed into the high-pressure reactor to form supercritical CO2 under this condition. The CO2 in the flue gas and the Pb in the concentrated solution are used to 2+ 、Cd 2+ , Cu 2+ 、Zn 2+ Cr 3+ Heavy metals and divalent Ca 2+ Mg 2+ The ions form metal carbonate precipitation, which is then centrifuged and then landfilled. The concentrated liquid containing COD is sprayed back into the incinerator to adjust the incineration furnace temperature, slow down coking, and reduce NO in the furnace flue gas. x content, decarbonized flue gas reduced pressure emission;

[0068] S5. The filtrate obtained in step S3 is treated with a reverse osmosis membrane (RO) to remove monovalent salts of NaCl and KCl. The high-salt concentrate enters the high-pressure reverse osmosis DTRO / HPRO and thermal evaporation MVR process, and then KCl and NaCl industrial salts are obtained through concentration and crystallization. The clear liquid or condensed clear liquid obtained by the RO, DTRO / HPRO, MVR, and concentration process meets the discharge standards.

[0069] It was determined that the total amount of dioxin residues in the mineralized and detoxified fly ash obtained in step S2 was 0.028 μgTEQ / kg, the leaching concentrations of heavy metals Pb, Cd, Cu, Zn, and Cr were 0.07 mg / L, 0.08 mg / L, 0.01 mg / L, 0.1 mg / L, and 0.02 mg / L, respectively, and the soluble chlorine content was 0.8%, which met the requirements for the treatment and disposal of fly ash from incineration of domestic waste in the Technical Specifications for Pollution Control of Fly Ash from Incineration of Domestic Waste (Trial) (HJ 1134-2020); the volume fraction of CO2 in the decarbonized flue gas in S4 was 1.5%, and the CO2 removal ratio reached 91%. The COD and NH4+ in the clear liquid or condensed clear liquid in S5 were 1.5% and 91% respectively. 4- -N, turbidity, chloride ion, total Pb, total Cd, total Cu, total Zn and total Cr concentrations were 44 mg / L, 0.8 mg / L, 4.7 NTU, 55 mg / L, 0.58 mg / L, 0.05 mg / L, 0.32 mg / L, 1.13 mg / L and 0.61 mg / L, respectively, which were all lower than the allowable discharge concentrations of the Comprehensive Sewage Discharge Standard (GB 8978-1996).

[0070] Example 2

[0071] A method for the coordinated disposal of three wastes from an incineration power plant for resource utilization comprises the following steps:

[0072] S1. The waste incineration fly ash and landfill leachate are passed through a three-stage countercurrent washing device, the solid-liquid ratio of the waste incineration fly ash to the landfill leachate is 1:2 (kg / L), at 25°C and a rotation speed of 200rpm, citric acid is added to adjust the pH to 4, and heavy metals and soluble salts in the waste incineration fly ash are separated by landfill leachate, and the mixed reaction is carried out for 1h, and then solid-liquid separation is performed to obtain preliminary washed fly ash and water washing liquid;

[0073] S2. The preliminary washed fly ash obtained in step S1 is introduced into a high-temperature and high-pressure reactor, and flue gas and landfill leachate are introduced into the high-temperature and high-pressure reactor, the solid-liquid ratio of the preliminary washed fly ash to the landfill leachate is 1:2 (kg / L), the temperature is maintained at 400°C by using steam waste heat, the reaction time is maintained for 2 hours, dioxins in the flue gas and fly ash are degraded, and CO2 in the flue gas is used to mineralize the fly ash, and after the low-temperature hot water hydrolysis degradation reaction, the fly ash is centrifuged and solid-liquid separated to obtain mineralized and detoxified fly ash, which is utilized as a resource together with the bottom ash;

[0074] S3. The washing liquid obtained by the solid-liquid separation in steps S1 and S2 is treated with a nanofiltration membrane (nanofiltration NF) to remove COD, ammonia nitrogen and heavy metals (HMs) to obtain a concentrated solution containing COD and heavy metals and a filtrate;

[0075] S4. The concentrated solution obtained in step S3 is passed into a high-pressure reactor at a pressure of 8.5 MPa and a temperature of 31 ° C. The remaining flue gas in step S2 is passed into the high-pressure reactor to form supercritical CO2 under this condition. The CO2 in the flue gas and the Pb in the concentrated solution are used to 2+ 、Cd 2+ , Cu 2+ 、Zn 2+ Cr 3+ Heavy metals and divalent Ca 2+ Mg 2+ The ions form metal carbonate precipitation, which is then centrifuged and then landfilled. The concentrated liquid containing COD is sprayed back into the incinerator to adjust the incineration furnace temperature, slow down coking, and reduce NO in the furnace flue gas. x content, decarbonized flue gas reduced pressure emission;

[0076] S5. The filtrate obtained in step S3 is treated with a reverse osmosis membrane (RO) to remove monovalent salts of NaCl and KCl. The high-salt concentrate enters the high-pressure reverse osmosis DTRO / HPRO and thermal evaporation MVR process, and then KCl and NaCl industrial salts are obtained through concentration and crystallization. The clear liquid or condensed clear liquid obtained by the RO, DTRO / HPRO, MVR, and concentration process meets the discharge standards.

[0077] It was determined that the total amount of dioxin residues in the mineralized and detoxified fly ash obtained in step S2 was 0.011 μgTEQ / kg, the leaching concentrations of heavy metals Pb, Cd, Cu, Zn, and Cr were 0.23 mg / L, 0.1 mg / L, 0.04 mg / L, 0.22 mg / L, and 0.10 mg / L, respectively, and the soluble chlorine content was 1.37%, which met the requirements for the treatment and disposal of fly ash from incineration of domestic waste in the Technical Specifications for Pollution Control of Fly Ash from Incineration of Domestic Waste (Trial) (HJ 1134—2020); the volume fraction of CO2 in the decarbonized flue gas in S4 was 1.2%, and the CO2 removal ratio reached 93%; the COD and NH4+ in the clear liquid or condensed clear liquid in S5 were 1.2% and 93% respectively. 4- -N, turbidity, chloride ion, total Pb, total Cd, total Cu, total Zn and total Cr concentrations were 46 mg / L, 0.9 mg / L, 4.9 NTU, 51 mg / L, 0.40 mg / L, 0.07 mg / L, 0.32 mg / L, 0.58 mg / L and 0.38 mg / L, respectively, which were all lower than the allowable discharge concentrations of the Comprehensive Sewage Discharge Standard (GB 8978-1996).

[0078] Example 3

[0079] A method for the coordinated disposal of three wastes from an incineration power plant for resource utilization comprises the following steps:

[0080] S1. The waste incineration fly ash and landfill leachate are passed through a three-stage countercurrent washing device, the solid-liquid ratio of the waste incineration fly ash to the landfill leachate is 1:10 (kg / L), acetic acid is added to adjust the pH to 5 at 55°C and a rotation speed of 120rpm, and the heavy metals and soluble salts in the waste incineration fly ash are separated by landfill leachate, and the mixed reaction is carried out for 30 minutes, and then the solid-liquid separation is carried out to obtain preliminary washed fly ash and water washing liquid;

[0081] S2. The preliminary washed fly ash obtained in step S1 is introduced into a high-temperature and high-pressure reactor, and flue gas and landfill leachate are introduced into the high-temperature and high-pressure reactor, the solid-liquid ratio of the preliminary washed fly ash to the landfill leachate is 1:10 (kg / L), the temperature is maintained at 300°C by using steam waste heat, the reaction time is maintained for 5 hours, dioxins in the flue gas and fly ash are degraded, and CO2 in the flue gas is used to mineralize the fly ash, and after the low-temperature hot water hydrolysis degradation reaction, the fly ash is centrifuged and solid-liquid separated to obtain mineralized and detoxified fly ash, which is utilized as a resource together with the bottom ash;

[0082] S3. The washing liquid obtained by the solid-liquid separation in steps S1 and S2 is treated with a nanofiltration membrane (nanofiltration NF) to remove COD, ammonia nitrogen and heavy metals (HMs) to obtain a concentrated solution containing COD and heavy metals and a filtrate;

[0083] S4. The concentrated solution obtained in step S3 is passed into a high-pressure reactor at a pressure of 7.5 MPa and a temperature of 35 ° C. The remaining flue gas in step S2 is passed into the high-pressure reactor to form supercritical CO2 under this condition. The CO2 in the flue gas and the Pb in the concentrated solution are used to 2+ 、Cd 2+ , Cu 2+ 、Zn 2+ Cr 3+ Heavy metals and divalent Ca 2+ Mg 2+ The ions form metal carbonate precipitation, which is then centrifuged and then landfilled. The concentrated liquid containing COD is sprayed back into the incinerator to adjust the incineration furnace temperature, slow down coking, and reduce NO in the furnace flue gas. x content, decarbonized flue gas reduced pressure emission;

[0084] S5. The filtrate obtained in step S3 is treated with a reverse osmosis membrane (RO) to remove monovalent salts of NaCl and KCl. The high-salt concentrate enters the high-pressure reverse osmosis DTRO / HPRO and thermal evaporation MVR process, and then KCl and NaCl industrial salts are obtained through concentration and crystallization. The clear liquid or condensed clear liquid obtained by the RO, DTRO / HPRO, MVR, and concentration process meets the discharge standards.

[0085] It was determined that the total amount of dioxin residues in the mineralized and detoxified fly ash obtained in step S2 was 0.048 μgTEQ / kg, the leaching concentrations of heavy metals Pb, Cd, Cu, Zn, and Cr were undetectable, 0.02 mg / L, undetectable, 0.18 mg / L, and 0.03 mg / L, respectively, and the soluble chlorine content was 0.5%, which met the requirements for the treatment and disposal of fly ash from incineration of domestic waste in the Technical Specifications for Pollution Control of Fly Ash from Incineration of Domestic Waste (Trial) (HJ 1134-2020); the volume fraction of CO2 in the decarbonized flue gas in S4 was 1.8%, and the CO2 removal ratio reached 89%; the COD and NH4+ in the clear liquid or condensed clear liquid in S5 were 0.1% and 0.2% respectively. 4- -N, turbidity, chloride ion, total Pb, total Cd, total Cu, total Zn and total Cr concentrations were 44 mg / L, 0.8 mg / L, 4.4 NTU, 66 mg / L, 0.37 mg / L, 0.03 mg / L, 0.10 mg / L, 0.42 mg / L and 0.53 mg / L, respectively, which were all lower than the allowable discharge concentrations of the Comprehensive Sewage Discharge Standard (GB 8978-1996).

[0086] Comparative Example 1

[0087] The same as Example 1, except that in S2, the preliminary water-washed fly ash obtained in step S1 is introduced into a high-temperature and high-pressure reactor, flue gas and landfill leachate are introduced into the high-temperature and high-pressure reactor, the solid-liquid ratio of the preliminary water-washed fly ash to the landfill leachate is 1:1 (kg / L), the temperature is maintained at 380°C using steam waste heat, and the reaction time is maintained for 3 hours.

[0088] It has been determined that the total amount of dioxin residues in the mineralized and detoxified fly ash obtained in step S2 is 0.07 μgTEQ / kg, the leaching concentrations of heavy metals Pb, Cd, Cu, Zn, and Cr are 0.79 mg / L, 1.17 mg / L, 0.47 mg / L, 13.4 mg / L, and 2.37 mg / L, respectively, and the soluble chlorine content is 11.3%. The leaching concentrations of Cd, Zn, and Cr, as well as the soluble chlorine content exceed the pollution control requirements for the treatment and disposal of fly ash from incineration of domestic waste in the Technical Specifications for Pollution Control of Fly Ash from Incineration of Municipal Solid Waste (Trial) (HJ 1134-2020).

[0089] Comparative Example 2

[0090] The same as Example 1, except that in S2, the preliminary water-washed fly ash obtained in step S1 is introduced into a high-temperature and high-pressure reactor, and flue gas and landfill leachate are introduced into the high-temperature and high-pressure reactor, the solid-liquid ratio of the preliminary water-washed fly ash to the landfill leachate is 1:8 (kg / L), the temperature is maintained at 200°C by using steam waste heat, the reaction time is maintained for 3 hours, dioxins in the flue gas and fly ash are degraded, and the CO2 in the flue gas is used to mineralize the fly ash, and after low-temperature hot water hydrolysis reaction, centrifugation and solid-liquid separation are performed to obtain mineralized and detoxified fly ash, which is utilized as a resource together with bottom ash.

[0091] It was determined that the total amount of dioxin residues in the mineralized and detoxified fly ash obtained in step S2 was 14.21 μgTEQ / kg, the leaching concentrations of heavy metals Pb, Cd, Cu, Zn, and Cr were 0.08 mg / L, 0.08 mg / L, not detected, 0.13 mg / L, and 0.04 mg / L, respectively, and the soluble chlorine content was 0.8%. The dioxin content exceeded the pollution control requirements for the treatment and disposal of fly ash from incineration of domestic waste in the Technical Specifications for Pollution Control of Fly Ash from Incineration of Municipal Solid Waste (Trial) (HJ 1134-2020).

[0092] Comparative Example 3

[0093] The same as Example 1, except that in S4, the concentrated solution obtained in step S3 is introduced into a high-pressure reactor, the pressure of the high-pressure reactor is 5 MPa, and the temperature is 32°C. The remaining flue gas in step S2 is introduced into the high-pressure reactor to form supercritical CO2 under this condition, and the CO2 in the flue gas is used to react with the Pb in the concentrated solution. 2+ 、Cd 2+ , Cu 2+ 、Zn 2+Cr 3+ Heavy metals and divalent Ca 2+ Mg 2+ The ions form metal carbonate precipitation, which is then centrifuged and then landfilled. The concentrated liquid containing COD is sprayed back into the incinerator to adjust the incineration furnace temperature, slow down coking, and reduce NO in the furnace flue gas. x content, decarbonized flue gas is discharged at reduced pressure.

[0094] It has been determined that the volume fraction of CO2 in the decarbonized flue gas in S4 is 14.5%, and the CO2 removal ratio is 13%.

[0095] Comparative Example 4

[0096] The same as Example 1, except that in S4, the concentrated solution obtained in step S3 is introduced into a high-pressure reactor, the pressure of the high-pressure reactor is 8 MPa, and the temperature is 25°C. The remaining flue gas in step S2 is introduced into the high-pressure reactor to form supercritical CO2 under this condition. The CO2 in the flue gas reacts with the Pb in the concentrated solution to form a supercritical CO2. 2+ 、Cd 2+ , Cu 2+ 、Zn 2+ Cr 3+ Heavy metals and divalent Ca 2+ Mg 2+ The ions form metal carbonate precipitation, which is then centrifuged and then landfilled. The concentrated liquid containing COD is sprayed back into the incinerator to adjust the incineration furnace temperature, slow down coking, and reduce NO in the furnace flue gas. x content, decarbonized flue gas is discharged at reduced pressure.

[0097] It has been determined that the volume fraction of CO2 in the decarbonized flue gas in S4 is 15.2%, and the CO2 removal ratio is 9%.

[0098] The results of characteristic pollutant concentrations of solid, liquid and gas products in the examples and comparative examples are detailed in Table 2.

[0099] Table 2 Characteristic pollutant concentrations of solid, liquid and gas products in the examples and comparative examples

[0100]

[0101]

[0102] It can be seen that compared with Example 1, the concentration of some heavy metals in the mineralized detoxified fly ash in Comparative Example 1 exceeds the standard, and the soluble chlorine content does not meet the requirements of fly ash resource utilization. The reason is that the solid-liquid ratio of the initial water-washed fly ash to the landfill leachate is 1:1 (kg / L), and the leaching efficiency of the leachate for heavy metals and soluble chlorides in the fly ash is not high at this ratio. The XRD mineral composition spectra of the original fly ash, Example 1 and the mineralized detoxified fly ash in Comparative Example 1 are shown in Figure 2 ,from Figure 2 It can also be seen from the XRD minerals of the mineralized detoxification fly ash that the fly ash in the comparative example still contains some sodium chloride and potassium chloride, while the mineralized detoxification fly ash in Example 1 only contains obvious calcium carbonate, quartz, calcium sulfate and amorphous aluminosilicate.

[0103] Compared with Example 1, the residual dioxin in the mineralized and detoxified fly ash of Comparative Example 2 is higher, far higher than the requirement for fly ash resource utilization. The reason is that when the low-temperature hot water hydrolysis process is adopted, the temperature is maintained at 200°C using the waste heat of steam, which is lower than the temperature requirement of the supercritical water reaction, resulting in a sharp drop in the dioxin degradation efficiency.

[0104] Compared with Example 1, the volume fraction of CO2 in the decarbonized flue gas in S4 is higher in Comparative Example 3. The reason is that the concentrated solution obtained in S3 is passed into a high-pressure reactor. The pressure of the high-pressure reactor is 5 MPa, which is lower than the critical pressure of supercritical carbon dioxide, which reduces the diffusion and solubility of CO2 in water, and reduces the capture capacity of alkaline earth metals Ca, Mg and heavy metals in fly ash for CO2.

[0105] Compared with Example 1, the volume fraction of CO2 in the decarbonized flue gas in Comparative Example 4 is higher in S4. The reason is that the concentrated solution obtained in S3 is passed into the high-pressure reactor. The temperature of the high-pressure reactor is 25°C, which is lower than the critical temperature of supercritical carbon dioxide, which reduces the diffusion and solubility of CO2 in water, and reduces the capture capacity of alkaline earth metals Ca, Mg and heavy metals in fly ash for CO2. In summary, it can be seen that the total amount of dioxin residues in the fly ash finally obtained in the embodiment of the present invention meets the requirements of HJ 1134; the heavy metal leaching concentration meets the national standard GB 8978, and can be mixed into the bottom ash for resource utilization; the leachate is discharged in compliance with the standards, and the concentrated solution is sprayed back into the furnace; the volume fraction of CO2 in the flue gas drops to less than 2%. In addition, the treatment process does not require drug consumption, which reduces the procurement costs of fly ash treatment chelating agents, leachate treatment flocculants, etc. in domestic waste incineration plants, and utilizes the flue gas heat energy of the boiler and the electricity generated by incineration power generation, which is clean and environmentally friendly.

[0106] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for the coordinated disposal of three wastes from incineration power plants, characterized in that: The following steps are involved: S1. The waste incineration fly ash and the landfill leachate are passed through a three-stage countercurrent washing device, mixed and reacted, and then solid-liquid separation is performed to obtain preliminary washed fly ash and washing liquid; S2. The preliminary washed fly ash obtained in step S1 is introduced into a high temperature and high pressure reactor, and flue gas and landfill leachate are introduced into the high temperature and high pressure reactor, and after low temperature and hot water hydrolysis reaction, centrifugation and solid-liquid separation are performed to obtain mineralized and detoxified fly ash and washing liquid, so as to realize resource utilization; S3. The washing liquid obtained by solid-liquid separation in steps S1 and S2 is treated by a nanofiltration membrane to obtain a concentrated solution containing COD and heavy metals and a filtrate; S4. The concentrated solution obtained in step S3 and the remaining flue gas in step S2 are passed into a high-pressure reactor, and the metal in the concentrated solution is removed by supercritical CO2 precipitation to form a metal carbonate precipitate. The metal carbonate precipitate is separated by centrifugation and the solid is stably landfilled. The obtained concentrated solution containing COD is sprayed back into the waste incinerator, and the decarbonized flue gas is discharged under reduced pressure; S5. The filtrate obtained in step S3 is treated with a reverse osmosis membrane to remove monovalent salts, and the high-salt concentrate enters a high-pressure reverse osmosis and thermal evaporation process, and then industrial salt is obtained by concentration and crystallization. The obtained clear liquid or condensed clear liquid meets the discharge standards.

2. The method for coordinated disposal of three wastes from incineration power plants according to claim 1 is characterized in that: The solid-liquid ratio of the waste incineration fly ash to the waste leachate in S1 is 1:(2-10) kg / L.

3. The method for coordinated disposal of three wastes from incineration power plants according to claim 1 is characterized in that: The temperature of the mixed reaction in S1 is 25-55°C, the rotation speed is 120-200 rpm, and the pH is 4-5.

4. The method for coordinated disposal of three wastes from incineration power plants according to claim 3 is characterized in that: One or more of salicylic acid, citric acid and acetic acid is added to adjust the pH to 4-5.

5. The method for coordinated disposal of three wastes from incineration power plants according to claim 1 is characterized in that: The solid-liquid ratio of the preliminary washed fly ash to the landfill leachate in S2 is 1: (2-10) kg / L.

6. The method for coordinated disposal of three wastes from incineration power plants according to claim 1 is characterized in that: The temperature of the low-temperature thermal hydrolysis reaction in S2 is 300-400° C., and the reaction time is 2-5 hours.

7. The method for coordinated disposal of three wastes from incineration power plants according to claim 1 is characterized in that: The pressure of the high-pressure reactor in S4 is 7.5-8.5 MPa, and the temperature is 31-35°C.

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