A system and method for treating incinerator fly ash with flue gas

Abstract

The application discloses a system and method for treating incineration fly ash by using flue gas, and belongs to the technical field of fly ash treatment of waste incineration, which comprises a fly ash pretreatment system and a reaction device, wherein the fly ash pretreatment system comprises a ball mill and a stirring device; fly ash and a dehalogenating agent are simultaneously added into the ball mill for mixing and ball milling; a mineralizing agent is further added, and after stirring, the mixture is introduced into the reaction device to be contacted with flue gas for reaction. The system can reuse the flue gas, and the concentrations of heavy metals and dioxins in the treated fly ash can meet the pollution concentration limit value in the Standard for Pollution Control on Domestic Waste Landfill Sites (GB 16889-2008).

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste incineration fly ash treatment, and particularly relates to a system and method for treating incineration fly ash by using flue gas. BACKGROUND

[0002] With the development of the times, municipal solid waste, medical waste and industrial production waste are increasing, and incineration of municipal solid waste, medical waste and industrial production waste is the main way to deal with these wastes in China at present. Incineration fly ash not only contains elements such as Cl, Ca, K, Na, Si, Al and O, but also contains high concentrations of heavy metals such as Hg, Pb, Cd, Cu, Cr and Zn, as well as very harmful dioxins. If not properly treated, it will cause serious environmental pollution, and these pollutants can pollute water bodies and soil, and further endanger the health of animals, plants and human bodies. How to treat fly ash and prevent dioxins and heavy metals from causing harm to nature is a problem that needs to be solved at present. In the prior art, heat treatment technology is often used, that is, sintering, melting, vitrification and gasification of fly ash, which is effective, but consumes a lot of energy, has high cost, and increases the risk of secondary pollution caused by pollutants entering the gas phase. In addition, the flue gas generated by waste incineration often contains excess carbon dioxide after desulfurization and denitrification treatment, which will directly enter the atmosphere and accelerate the formation of the greenhouse effect. How to fully utilize the carbon dioxide in the flue gas is also a problem that needs to be solved at present. Therefore, it is particularly necessary to invent a system and method for treating incineration fly ash by using flue gas. SUMMARY

[0003] In view of the above shortcomings of the prior art, the first aspect of the present application provides a fly ash pretreatment system which can pretreat fly ash and activate fly ash to prepare for subsequent reactions. The second aspect of the present application provides a system for treating incineration fly ash by using flue gas, which fully utilizes the waste heat generated by incineration of waste and flue gas containing a large amount of carbon dioxide to treat fly ash. The third aspect of the present application provides a method for treating incineration fly ash by using flue gas, which combines flue gas containing a large amount of carbon dioxide with dehalogenating agent and mineralizing agent to treat fly ash, so that the concentration of dioxins and heavy metals in the final fly ash meets the pollution concentration limit value in the Standard for Pollution Control on the Landfill Site of Municipal Solid Waste (GB 16889-2008). The specific implementation is as follows:

[0004] The first aspect of the present application provides a fly ash pretreatment system, which comprises a first batching tank, a second batching tank, a third batching tank, a ball mill, a stirring device and a motor; the outlets of the first batching tank and the second batching tank are connected to the inlet of the ball mill; the ball mill is provided with a first gear at one end, and the outlet of the ball mill is connected to the stirring device; the output end of the motor is provided with a second gear; the stirring device comprises a stirring container and a stirring paddle, and the top end of the stirring paddle is provided with a third gear; the first gear and the third gear are respectively engaged with the second gear; the outlet of the third batching tank is connected to the stirring container; and the first batching tank, the second batching tank, the third batching tank and the stirring device are all provided with a weighing sensor.

[0005] The second aspect of the present application provides a system for treating incineration fly ash by using flue gas, which comprises the fly ash pretreatment system and a reaction device; the reaction device comprises a cavity, and the cavity is connected to the outlet of the stirring device; the bottom of the reaction device is provided with a slurry outlet, and the upper part of the reaction device is provided with a flue gas inlet and a flue gas outlet.

[0006] In the system of the present application, the original fly ash enters the ball mill through the first batching tank, and the dehalogenating agent enters the ball mill through the second batching tank at the same time; the weight ratio of the original fly ash and the dehalogenating agent can be controlled within a suitable range through the weighing sensors at the bottom of the first batching tank and the second batching tank; after the grinding of the ball mill is completed, the ground fly ash is introduced into the stirring device, and the mineralizing agent is added into the stirring device through the third batching tank; the weight ratio of the ground fly ash and the mineralizing agent can be controlled within a suitable range through the weighing sensors at the bottom of the stirring container and the third batching tank; water is added into the stirring container, and the stirring container is stirred to obtain a slurry; the slurry is introduced into the reaction device, and flue gas is introduced into the reaction device through the flue gas inlet; the flue gas and the slurry are fully contacted and reacted in the reaction device; the reacted slurry is introduced into the next process through the slurry outlet, and the flue gas is discharged through the flue gas outlet.

[0007] Preferably, the reaction device is provided with a compressor, the compressor is connected to the cavity, and the cavity is provided with a pressure sensor. The pressure sensor is electrically connected to the compressor, so that the pressure in the reaction device can be controlled. Further preferably, the pressure in the reaction device is 0-2 MPa.

[0008] Preferably, the cavity is provided with a temperature sensor. The temperature sensor can monitor the temperature in the cavity.

[0009] Preferably, the system further comprises a fly ash drying device. The fly ash drying device is used to reduce the water content of the fly ash, and can accelerate the reaction of the fly ash with the dehalogenating agent, the mineralizing agent and carbon dioxide in the flue gas.

[0010] Preferably, the fly ash drying device comprises a drying pipe, a sandwich layer is arranged outside the drying pipe, and a pipe is arranged in the sandwich layer. Through the pipe in the sandwich layer, an external heat source can be applied to the drying pipe to increase the temperature in the drying pipe. Further preferably, a flue gas treatment device and a condensation system of the incineration system are further included, and an outlet pipe of the condensation system is connected to the pipe. The sandwich layer and the pipe can utilize the condensate water with a large amount of heat after the over-condensation of the incineration system, and the heat can be used twice to dry the fly ash. The flue gas treatment device can treat the flue gas by desulfurization and denitrification, and then use the treated flue gas for subsequent reactions.

[0011] Preferably, a storage tank is further included. The storage tank can temporarily store the dried fly ash, and then the fly ash can be treated by solidification after reaching a certain amount.

[0012] Preferably, a fly ash solidification device is further included. The fly ash can be obtained after the fly ash solidification device, which is convenient for disposal, such as landfill.

[0013] Preferably, a blowing device is arranged in the first batching tank, the second batching tank, the third batching tank, the ball mill and the stirring device. The blowing device can clean the inner wall of the pipe and help to exhaust the contents.

[0014] The third aspect of the present application provides a method for treating fly ash by using flue gas, which uses the system for treating fly ash by using flue gas, and comprises the following steps:

[0015] Mixing and grinding the original fly ash with a dehalogenizing agent to obtain dehalogenized fly ash; mixing the dehalogenized fly ash with a mineralizing agent, adding water, and stirring to obtain a slurry; reacting the slurry with flue gas treated by desulfurization and denitrification, drying, solidifying, and curing to obtain a fly ash solidification body;

[0016] Preferably, the dehalogenizing agent comprises aluminum and aluminum oxide.

[0017] In the present application, the Al / γ-Al2O3 has two functions, first, the surface of γ-Al2O3 has active five-coordinated [AlO5] 7-The group provides electrons under the driving force of local temperature rise, dislocation, surface activation and the like caused by the mechanical force of the ball mill, can break the C-O bond in dioxin, and has the effect of ring opening; the Al powder has metal ductility, and will first become a sheet structure under the extrusion of the ball, and then will be broken to generate a large amount of surface under the action of the crystalline salt such as NaCl and KCl in the fly ash which has an angular structure, has a high reduction effect, can break the C-Cl bond in dioxin, and has the effect of efficient dechlorination; the Al and gamma-Al2O3 have a synergistic effect, and under the mechanochemical action, the dioxin in the fly ash is degraded; secondly, after the ball milling, the particle size of the Al / gamma-Al2O3 powder is greatly reduced, the Al is gradually oxidized into Al2O3, together with the gamma-Al2O3, has very high alkali solubility, can provide [Al(OH)4 - ] under the conditions of mineralization and hydration, promotes the generation of the hydration products such as hydrated calcium silicate, AFm and AFt, and provides a material basis for the mineralization of carbon dioxide and the solidification of heavy metals.

[0018] In the method of the application, the reaction of the slurry and the flue gas is divided into two stages of carbonization and hydration: in the carbonization stage, the magnesium oxide can release hydroxyl ions, the sodium disilicate has the effect of slow release of alkalinity, and the mutual action of the two can ensure that the fly ash system in the carbonization stage is in the pH range of efficient carbonization, avoids the problem that the low alkalinity after carbonization leads to difficult solidification, and also avoids the problem that the rapid release of alkalinity leads to low utilization efficiency, and causes the problem of reverse alkaline of the solidified body in the later stage; at the same time, in the process of the contact of the fly ash and the flue gas, the carbonates such as calcium carbonate and magnesium carbonate generated by carbonization can be used as raw materials for the hydration reaction; in the hydration stage, the sodium disilicate plays the role of ion exchange, improves the Ca / Al ratio and Ca / Si ratio in the slurry, provides silicate needed for hydration, and the magnesium oxide can react with the chloride salt in the fly ash to promote the generation of 3Mg(OH)2·MgCl2·8H2O and 5Mg(OH)2·MgCl2·8H2O, which can exist stably in a lower pH range (pH=9-10), and ensures the long-term safety performance of the solidified fly ash in the landfill site; the carbonates generated in the carbonization stage are combined with the raw materials, the fly ash and the aluminum to generate layered Ca-(Al / Fe)-CO3-LDH materials and columnar Ca-(Al / Fe)-CO3-AFt materials, thereby solidifying the heavy metals, and the Ca-(Al / Fe)-CO3-LDH and Ca-(Al / Fe)-CO3-AFt of the carbonate type have lower solubility than the hydroxyl type and halogen type LDH and AFt, are easier to generate, and are more stable. The reaction process is as follows:

[0019] Slow release of alkalinity of sodium disilicate:

[0020]

[0021] Ion exchange of sodium disilicate:

[0022]

[0023] Other reaction processes:

[0024] 5Mg(OH)2·MgCl2·8H2O + 2CO2→ Mg(OH)2·MgCl2·2MgCO3·8H2O + 2Mg(OH)2 + 2H2O

[0025] 3Mg(OH)2·MgCl2·8H2O + 2CO2→ Mg(OH)2·MgCl2·2MgCO3·6H2O + 4H2O

[0026] In the following reaction formula, M is Ca or Mg:

[0027] 3CaO·Al2O3·Ca(OH)2·10H2O + MCO3 + H2O→ 3CaO·Al2O3·CaCO3·11H2O + M(OH)2

[0028] 3CaO·Al2O3·CaCl2·10H2O + MCO3 + H2O→ 3CaO·Al2O3·CaCO3·11H2O + MCl2

[0029] 3CaO·Al2O3·CaSO4·12H2O + MCO3→ 3CaO·Al2O3·CaCO3·11H2O + MSO4 + H2O

[0030] The set retarding type water reducing agent in the application can effectively improve the consistency of fly ash slurry and delay the hydration time, so as to ensure that the slurry is in a flowing state in the entire carbonation stage and facilitate fluidization. The air entraining agent can make the carbon dioxide in the gas phase uniformly dispersed in the fly ash slurry during the fly ash fluidization movement, increase the contact between the gaseous carbon dioxide and the fly ash slurry, and improve the carbonation efficiency. In the method of the application, aluminum and aluminum oxide are added, which not only activates the fly ash in the grinding stage and is beneficial to the degradation of dioxin and other pollutants in the fly ash, but also promotes the contact reaction between the fly ash and the carbon dioxide in the flue gas to generate carbonates in the carbonation stage, and also participates in the generation of layered Ca-(Al / Fe)-CO3-LDH materials and columnar Ca-(Al / Fe)-CO3-AFt materials to solidify heavy metals in the hydration stage.

[0031] Preferably, the mineralizer comprises 50-70% sodium disilicate, 30-40% magnesium oxide, 0.5-1.5% set retarding type water reducing agent, and 0.005-0.015% air entraining agent.

[0032] Preferably, the mass ratio of aluminum and aluminum oxide is (2-5): 1.

[0033] Preferably, the mass ratio of the original fly ash to the dehalogenizing agent is (5-8): 1.

[0034] Preferably, the grinding time is 3-8h.

[0035] Preferably, the mass ratio of dehalogenated fly ash to mineralizing agent is (4-9):1.

[0036] Preferably, the mass of water is 50-70% of the total mass of dehalogenated fly ash and mineralizing agent.

[0037] Preferably, the concentration of carbon dioxide in the flue gas is >15%.

[0038] Preferably, the carbonization time is 0.5-1.5h.

[0039] Preferably, after the fly ash is dried, the water content of the fly ash is ≤30%.

[0040] Preferably, the solidification is carried out by pressurized solidification, the pressure of the pressurization is 25-45kN, and the time of the pressurization is 17-28s.

[0041] Preferably, the curing time is 3-7d.

[0042] Compared with the prior art, the present application has the advantages of:

[0043] 1、The system of the present application utilizes the flue gas containing a large amount of carbon dioxide after desulfurization and denitrification treatment, not only saving cost, but also realizing carbon reduction treatment of the flue gas;

[0044] 2、The system of the present application can use the heat generated during the fly ash incineration process to dry the carbonized fly ash, avoiding the waste of heat energy and saving the processing cost of fly ash;

[0045] 3、The system of the present application is simple and easy to operate, with the aid of the gear structure, only one motor is used to control the ball mill and the stirring paddle at the same time, not only saving the installation space, but also reducing the cost;

[0046] 4、The dehalogenating agent of the present application can act on fly ash dioxin degradation and carbonization at the same time, and the mineralizing agent can act on fly ash carbonization and heavy metal stabilization at the same time, both of which are widely available, and through the combination of the system of the present application, fly ash dioxin degradation-carbon capture-heavy metal stabilization is realized. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a structural schematic view of the system of the present application for treating incinerated fly ash with flue gas;

[0048] Figure 2 is a structural schematic view of the reaction device of the present application;

[0049] Figure 3 is a schematic view of the position relationship of the reaction device and the compressor of the present application;

[0050] Figure 4 Structure diagram of the system for treating incineration fly ash by using flue gas and waste heat according to the present application;

[0051] Figure 5 Structure diagram of the drying pipe according to the present application;

[0052] In the figure: 1, first batching tank; 2, second batching tank; 3, third batching tank; 4, ball mill; 41, inlet; 42, first gear; 5, stirring device; 51, stirring container; 52, stirring paddle; 6, motor; 61, second gear; 8, cavity; 9, weighing sensor; 10, first pipeline; 11, third gear; 12, inlet end; 13, second pipeline; 14, slurry outlet; 15, flue gas inlet; 16, flue gas outlet; 17, drying pipe; 171, interlayer; 172, third pipeline; 1721, inlet end; 173, inlet end; 174, outlet end; 18, incineration system; 19, condensation system; 191, third pipeline; 20, storage tank; 21, purging device; 22, flue gas treatment system; 221, fourth pipeline; 23, valve; 24, water injection port; 25, fly ash solidification equipment; 26, sampling port; 27, compressor; 271, fifth pipeline; 28, pressure sensor; 29, temperature sensor. DETAILED DESCRIPTION

[0053] In order to further illustrate the present application, the technical solutions provided by the present application are described in detail below in conjunction with examples, but they should not be understood as limiting the protection scope of the present application.

[0054] A method for treating incineration fly ash by using flue gas according to the present application, comprising the following steps:

[0055] Mixing and grinding the original fly ash with a dehalogenizing agent to obtain dehalogenized fly ash;

[0056] Mixing the dehalogenized fly ash with a mineralizing agent, adding water, and stirring to obtain a slurry;

[0057] Introducing the slurry and flue gas treated by desulfurization and denitrification into a closed container for reaction, drying, solidification, and curing to obtain a fly ash solidification body;

[0058] The mineralizing agent comprises sodium disilicate, magnesium oxide, a retarder-type water reducing agent, and an air entraining agent; and the dehalogenizing agent comprises aluminum and aluminum oxide.

[0059] Preferably, the mineralizing agent comprises 50-70% of sodium disilicate, 30-40% of magnesium oxide, 0.5-1.5% of a retarder-type water reducing agent, and 0.005-0.015% of an air entraining agent.

[0060] Alternatively, the mass ratio of aluminum to aluminum oxide is (2-5):1.

[0061] Optionally, the mass ratio of the original fly ash to the dehalogenating agent is (5-8):1.

[0062] Optionally, the grinding time is 3-8h.

[0063] Optionally, the mass ratio of the dehalogenated fly ash to the mineralizing agent is (4-9):1.

[0064] Optionally, the mass of the water is 50-70% of the total mass of the dehalogenated fly ash and the mineralizing agent.

[0065] Optionally, the concentration of carbon dioxide in the flue gas is >15%.

[0066] Optionally, the reaction time is 0.5-1.5h.

[0067] Optionally, after the fly ash is dried, the water content of the fly ash is ≤30%.

[0068] Optionally, the curing is performed by pressurized curing, the pressure of the pressurization is 25-45kN, and the time of the pressurization is 17-28s.

[0069] Optionally, the curing time is 3-7d.

[0070] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0071] Embodiments

[0072] Referring to Figure 1 The embodiments of the present application provide a system for treating incineration fly ash by using flue gas, which comprises a fly ash pretreatment system and a reaction device. The fly ash pretreatment system comprises a first batching tank 1, a second batching tank 2, a third batching tank 3, a ball mill 4, a stirring device 5, and a motor 6. The outlet of the first batching tank 1 and the outlet of the second batching tank 2 are both connected to the inlet 41 of the ball mill 4 through a first pipeline 10. A first gear 42 is arranged around the ball mill 4 at an end of the ball mill 4 away from the inlet 41. The outlet of the ball mill 4 is connected to the stirring device 5 through the first pipeline 10. The output end of the motor 6 is provided with a second gear 61. The stirring device 5 comprises a stirring container 51 and a stirring paddle 52. The top end of the stirring paddle 52 is provided with a third gear 11. The outlet of the third batching tank 3 is connected to the stirring container 51 through the first pipeline 10. Weighing sensors 9 are arranged in the first batching tank 1, the second batching tank 2, the third batching tank 3, and the stirring device 5.

[0073] Referring to Figure 2As shown, the reaction device comprises a cavity 8, the inlet end 12 of the reaction device is connected with the outlet of the stirring device 5 through a second pipeline 13; the bottom of the reaction device away from the inlet end 12 is provided with a slurry outlet 14, and the upper ends of the reaction device are respectively provided with a flue gas inlet 15 and a flue gas outlet 16.

[0074] In the system of the embodiment of the present application, the raw fly ash is weighed in the first batching tank 1 and then enters the ball mill 4, the dehalogenating agent is weighed in the second batching tank 2 and then enters the ball mill 4, the motor 6 is started, the raw fly ash and the dehalogenating agent are mixed and ground in the ball mill 4, the ground fly ash is introduced into the stirring device 5 through the first pipeline 10, the mineralizing agent is weighed in the third batching tank 3 and then is added into the stirring device 5; water is added into the stirring container 51 and is stirred to obtain a slurry; the slurry is introduced into the cavity 8 of the reaction device through the second pipeline 13, and flue gas is introduced into the cavity 8 through the flue gas inlet 15 of the reaction device at the same time, so that the flue gas and the slurry are fully contacted and reacted in the cavity 8; the reacted slurry is introduced into the next process through the slurry outlet 14, and the flue gas is discharged through the flue gas outlet 16.

[0075] Referring to Figure 3 As shown, in order to control the pressure and temperature in the cavity 8, the embodiment of the present application is provided with a pressure sensor 28 and a temperature sensor 29 in the cavity 8, and a compressor 27 is arranged on one side of the reaction device, the compressor 27 is connected with the cavity 8 through a fifth pipeline 271, and the pressure sensor 28 is electrically connected with the compressor 27, so that the pressure in the cavity 8 can be controlled.

[0076] Referring to Figures 4-5 As shown, in order to reduce the water content of the fly ash and promote further reaction, optionally, the system for treating incineration fly ash by using flue gas according to the embodiment of the present application further comprises a fly ash drying device. Further optionally, the fly ash drying device comprises a drying pipe 17, a cladding layer 171 is arranged around the drying pipe 17, and a third pipeline 172 is arranged in the cladding layer 171. Through the third pipeline 172 in the cladding layer 171, an external heat source can be applied to the drying pipe 17 to increase the temperature in the drying pipe 17 and thus dry the fly ash. The inlet end 173 of the drying pipe 17 is connected with the slurry outlet 14 of the reaction device through the second pipeline 13; and the outlet end 174 of the drying pipe 17 is led out through the first pipeline 10. Further preferably, the system for treating incineration fly ash by using flue gas according to the embodiment of the present application further comprises an incineration system 18, the incineration system 18 is provided with a condensation system 19, and the outlet end of the condensation system 19 is connected with the inlet end 1721 of the third pipeline 172 through a third pipeline 191, so that the waste heat of the incineration fly ash is utilized. Valves 23 are arranged at the inlet ends of the first pipeline 10, the second pipeline 13, the third pipeline 191 and the fourth pipeline 221.

[0077] Referring to Figure 4As shown, in order to temporarily store the dried fly ash, and to concentrate the fly ash for solidification treatment after reaching a certain amount, the system for treating incineration fly ash by using flue gas according to the embodiment of the application further comprises a storage tank 20. In order to further solidify the fly ash and facilitate subsequent disposal, the system for treating incineration fly ash by using flue gas according to the embodiment of the application further comprises a fly ash solidification device 25. In order to facilitate cleaning of the inner wall of the pipe and help to exhaust the contents, the first batching tank 1, the second batching tank 2, the third batching tank 3, the ball mill 4 and the stirring device 5 are each provided with a blowing device 21. In order to realize reuse of the flue gas, the system for treating incineration fly ash by using flue gas according to the embodiment of the application further comprises a flue gas treatment system 22, and the outlet end of the flue gas treatment system 22 is connected to the flue gas inlet 15 of the reaction device through a fourth pipeline 221. In order to facilitate water addition, the stirring container 51 is provided with a water inlet 24.

[0078] Referring to Figure 5 As shown, in order to facilitate sampling and moisture content measurement of the dried fly ash, the embodiment of the application is provided with a sampling port 26 at one end of the drying pipe 17 close to the outlet end 174.

[0079] The embodiment of the application further provides a method for treating incineration fly ash by using flue gas, comprising the following steps:

[0080] S1, the raw fly ash generated by the incineration system 18 is introduced into the first batching tank 1 through the first pipeline 10, and weighed; the aluminum and aluminum oxide in the dehalogenizing agent are uniformly mixed at a ratio of 3:1, and the raw fly ash and the dehalogenizing agent are mixed at a ratio of 6:1, and the amount of the dehalogenizing agent is calculated; the dehalogenizing agent is added to the second batching tank, and weighed; the valve 23 on the first pipeline 10 below the outlets of the first batching tank 1 and the second batching tank 2 is opened, and the raw fly ash and the dehalogenizing agent are introduced into the ball mill 4;

[0081] S2, the motor 6 is started, the ball mill 4 is driven to rotate and grind by the second gear 61 and the first gear 42, after 6 hours, the motor 6 is turned off, and the dehalogenated fly ash is obtained; the dehalogenated fly ash is introduced into the stirring container 51 through the pipeline 10, and weighed; the dehalogenated fly ash and the mineralizing agent are mixed at a ratio of 7:1, the weight of the mineralizing agent is calculated, the mineralizing agent is added to the third batching tank 3, and weighed; water is added to the stirring container 51 through the water inlet 24, the amount of water added is 60% of the total mass of the dehalogenated fly ash and the mineralizing agent, and stirring is performed for 1h, and the slurry is obtained;

[0082] S3, the slurry of step S2 is introduced into the cavity 8 of the reaction device through the second pipeline 13, and the flue gas discharged from the flue gas treatment system 22 is introduced into the cavity 8 of the reaction device through the fourth pipeline 221 and the flue gas inlet 15 of the reaction device, so that the slurry and the flue gas are fully contacted and reacted. The reaction time is 1h;

[0083] S4. After the reaction in step S3 is completed, the reacted slurry is introduced into the drying pipe 17 through the slurry outlet 14 and the second pipe 13. The inlet end 1721 of the third pipe 172 in the jacket 171 of the drying pipe 17 is connected to the outlet end of the condensation system 19 that is matched with the incineration system 18. The residual heat of the incineration fly ash is used to dry the fly ash. An appropriate amount of fly ash is taken through the sampling port 26 to measure the moisture content. The moisture content of the dried fly ash is 16%.

[0084] S5. The dried fly ash is stored in the storage tank 20. After accumulating to a suitable amount, it is introduced into the fly ash solidification equipment 25 through the first pipe 10 and pressurized to form a solidified fly ash body that can be safely disposed of.

[0085] Test case

[0086] (1) Sample category:

[0087] Sample 1: Raw fly ash

[0088] Sample 2: A mixture of raw fly ash and dehalogenating agent

[0089] Sample 3: Dehalogenated fly ash

[0090] Sample 4: Dried fly ash without dehalogenating agent

[0091] Sample 5: Dried fly ash without added mineralizer

[0092] Sample 6: Dried fly ash

[0093] Sample 7: Fly ash formed by pressing dried flowers

[0094] (2) Toxicity leaching test

[0095] Toxicity leaching tests were conducted on samples 1-7, and the pollution concentration limits were evaluated according to the "Pollution Control Standard for Municipal Solid Waste Landfills" (GB16889-2008).

[0096] Carbonation conversion rate η = Δm / m0 * 100%, where Δm is the mass loss of each sample after contact with 15% volume fraction of flue gas carbonation in the thermogravimetric experiment between 700-950℃, in g; m0 is the initial mass of each sample before contact with flue gas, in g.

[0097] The experimental results are shown in Table 1 below.

[0098] Table 1. Results of toxicity leaching tests on samples 1-7

[0099]

[0100] As can be seen from Table 1, the heavy metal leaching concentration and dioxin content in sample 1-2 have little change, because sample 2 only mixes the original fly ash with the dehalogenating agent without any reaction, so the test results of sample 1-2 have little difference, and the fly ash content is diluted due to the introduction of the dehalogenating agent in sample 2, and the carbonation conversion rate of the fly ash decreases.

[0101] Sample 3 only grinds and mixes the original fly ash with the dehalogenating agent, the dioxin in the fly ash is decomposed and the content is greatly reduced, while the heavy metal is only activated, part of the trivalent Cr is oxidized to the more toxic hexavalent Cr, and the total Cr and hexavalent Cr leaching concentrations even slightly increase, the Pb and Cd belong to cationic heavy metals, and the leaching concentrations change little, and the carbonation conversion rate of the fly ash slightly increases to 9.25%, because the ball milling process makes the fly ash particle size finer, increases the specific surface area, and promotes the carbonation process.

[0102] Compared with sample 1, the heavy metal Pb and Cd leaching concentrations in sample 4 decrease to below the standard limit value of the Standard for Pollution Control on the Landfill Site for Domestic Waste (GB 16889-2008), while the total Cr and hexavalent Cr leaching concentrations decrease, but are still higher than the leaching concentration limit value requirement, and the dioxin content almost does not change, because the dehalogenating agent is not used in sample 4, the dioxin cannot be decomposed, the Al content in the fly ash system is not enough to generate the layered Ca-(Al / Fe)-CO3-LDH material and the columnar Ca-(Al / Fe)-CO3-AFt material to solidify the heavy metal hexavalent Cr, and the mineralizer has a high solidification efficiency for Pb and Cd, and the fly ash carbonation conversion rate greatly increases to 16.55%, because the mineralizer is added to provide alkalinity and Mg2+, which promotes the fly ash carbon capture efficiency.

[0103] Compared with sample 1, the heavy metal Pb and Cd leaching concentrations in sample 5 decrease, but are still higher than the leaching concentration limit value requirement, the total Cr leaching concentration changes little, the hexavalent Cr leaching concentration increases, and the dioxin content greatly decreases to below the standard limit requirement, because the mineralizer is not used in sample 5, the dioxin is decomposed under the action of the dehalogenating agent, the dehalogenated fly ash produces carbonation products PbCO3 and CdCO3 after carbonation, and the leaching concentrations decrease, but the sufficient hydration products are not produced, the stabilization degree is limited, and the leaching concentrations are still high, while the fly ash is activated by ball milling, and the hexavalent Cr leaching concentration increases, and because the mineralizer is not added, the fly ash carbonation conversion rate almost does not change compared with the original ash.

[0104] Compared with sample 1, the concentrations of heavy metal leaching and dioxin in samples 6-7 meet the pollution concentration limit value in the Standard for Pollution Control on Solid Waste Landfill Sites (GB 16889-2008), and the concentration of sample 7 is lower than that of sample 6, which shows that the combination of dehalogenating agent and mineralizing agent can effectively utilize flue gas to treat fly ash, so that the heavy metals and dioxins in fly ash meet the Standard for Pollution Control on Solid Waste Landfill Sites (GB 16889-2008); compared with sample 6, sample 7 greatly reduces the porosity of dried fly ash through static pressure, produces physical encapsulation, and further reduces the heavy metal leaching concentration, therefore, the concentrations of heavy metals and dioxins in samples 6-7 meet the pollution concentration limit value in the Standard for Pollution Control on Solid Waste Landfill Sites (GB 16889-2008); the carbonation conversion rate of fly ash is greatly increased to 21.3% and 21.5%, because the mineralizing agent provides alkalinity and Mg2+, and the dehalogenating agent promotes the generation of layered Ca-(Al / Fe)-CO3-LDH and columnar Ca-(Al / Fe)-CO3-AFt carbonation products, further promoting the carbon capture efficiency of fly ash.

[0105] The above detailed description of the embodiments of the present application, but the present application is not limited to the specific details of the above-described embodiments. Within the scope of the claims and technical concepts of the present application, the technical solutions of the present application can be modified and changed in many simple ways, and these simple modifications all belong to the protection scope of the present application.

Claims

1. A system for treating incineration fly ash using flue gas, characterized in that, Includes fly ash pretreatment system and reaction unit; The fly ash pretreatment system includes a first batching tank, a second batching tank, a third batching tank, a ball mill, a stirring device, and a motor; the outlets of the first batching tank and the second batching tank are both connected to the inlet of the ball mill; a first gear is provided at one end of the ball mill, and the outlet of the ball mill is connected to the stirring device; a second gear is provided at the output end of the motor; the stirring device includes a stirring container and a stirring paddle, and a third gear is provided at the top of the stirring paddle; the first gear and the third gear respectively mesh with the second gear; the third gear... The outlets of the three batching tanks are connected to the mixing container; each of the first, second, and third batching tanks and the mixing device is equipped with a weighing sensor; the first batching tank contains raw fly ash, the second batching tank contains a dehalogenating agent, and the third batching tank contains a mineralizing agent; the dehalogenating agent includes aluminum and alumina, and the mineralizing agent comprises, by mass fraction, 50-70% sodium disilicate, 30-40% magnesium oxide, 0.5-1.5% retarding water-reducing agent, and 0.005-0.015% air-entraining agent; The reaction device includes a cavity that is connected to the outlet of the stirring device; the bottom of the reaction device is provided with a slurry outlet, and the upper part of the reaction device is provided with a flue gas inlet and a flue gas outlet; It also includes a fly ash drying device, which includes a drying pipe, an outer layer around the drying pipe, and a pipe inside the outer layer; It also includes a condensation system for the flue gas treatment device and the incineration system, wherein the outlet pipe of the condensation system is connected to the pipeline.

2. The system for treating incineration fly ash using flue gas according to claim 1, characterized in that, The mixing container is equipped with a water inlet.

3. The system for treating incineration fly ash using flue gas according to claim 1, characterized in that, It also includes fly ash curing equipment.

4. The system for treating incineration fly ash using flue gas according to claim 1, characterized in that, The first batching tank, the second batching tank, the third batching tank, the ball mill, and the stirring device are all equipped with a purging device.

5. A method for treating incineration fly ash using flue gas, characterized in that, The system for treating incinerator fly ash using flue gas as described in any one of claims 1-4 includes the following steps: The raw fly ash is mixed with the dehalogenating agent and ground to obtain dehalogenated fly ash; The dehalogenated fly ash is mixed with a mineralizing agent, water is added, and the mixture is stirred to obtain a slurry. The slurry is reacted with flue gas that has undergone desulfurization and denitrification treatment, and then dried, solidified, and cured to obtain solidified fly ash. The dehalogenating agent includes aluminum and aluminum oxide.

6. The method for treating incineration fly ash using flue gas according to claim 5, characterized in that, The mineralizing agent comprises, by mass fraction, 50-70% sodium disilicate, 30-40% magnesium oxide, 0.5-1.5% retarding water-reducing agent, and 0.005-0.015% air-entraining agent.

Images