CN-121972490-A - Low-temperature decoupling flue gas treatment system and method for household garbage incineration fly ash

CN121972490ACN 121972490 ACN121972490 ACN 121972490ACN-121972490-A

Abstract

The invention discloses a low-temperature pyrolysis flue gas coupling treatment system and method for household garbage incineration fly ash, and belongs to the field of treatment of household garbage incineration fly ash. The system comprises a fly ash pretreatment unit, a pyrolysis unit, a shielding gas supply unit and a flue gas purification unit, wherein CO 2 obtained by carbon capture of waste incineration flue gas is used as pyrolysis shielding gas, fly ash is mixed with additives and then sent to the pyrolysis unit to complete low-temperature pyrolysis, after the pyrolysis flue gas is subjected to multistage purification, the flue gas rich in CO 2 can be recycled to a carbon capture procedure, and the flue gas reaching the standard is directly discharged and is matched with a dust recycling structure. The invention realizes the source reduction and carbon emission reduction of pollutants, reduces the energy consumption and the operation cost of the system, can be coupled with the facilities of the existing incineration plants for transformation, and ensures the stable standard emission of the flue gas.

Inventors

TAO YINGXIANG
LI YU
WU ZHONGYONG
PENG ZEJUN
YU BENHONG
LU YUFENG
LIU MIN
FU YUFENG

Assignees

重庆三峰卡万塔环境产业有限公司

Dates

Publication Date: 20260505
Application Date: 20260331

Claims (10)

1. The low-temperature pyrolysis flue gas coupling treatment system for the household garbage incineration fly ash is characterized by comprising: a fly ash pretreatment unit (100) for mixing fly ash generated by incineration of household garbage with additives; The pyrolysis unit (200) is communicated with the fly ash pretreatment unit (100) and is used for carrying out low-temperature pyrolysis treatment on the mixed fly ash; A shielding gas supply unit (300) for receiving the flue gas treated by the garbage incineration system, capturing carbon of the flue gas to obtain CO 2 , and introducing CO 2 serving as pyrolysis shielding gas into the pyrolysis unit (200); And the smoke purification unit (400) is communicated with the exhaust end of the pyrolysis unit (200) and is used for purifying and discharging smoke generated by pyrolysis and recycling the purified smoke rich in carbon dioxide to the protective gas supply unit (300).
2. The system of claim 1, wherein the fly ash pretreatment unit (100) comprises a raw ash bin (101), an additive bin (102), a mixer (103) and a feed bin (104), wherein the outlets of the raw ash bin (101) and the additive bin (102) are each in communication with an inlet of the mixer (103), and wherein an outlet of the mixer (103) is in communication with an inlet of the feed bin (104).
3. The system according to claim 2, wherein the pyrolysis unit (200) comprises a pyrolysis furnace (201) and a pyrolysis ash bin (202), wherein an outlet of the feeding bin (104) is communicated with a fly ash inlet of the pyrolysis furnace (201), a solid discharge port of the pyrolysis furnace (201) is communicated with an inlet of the pyrolysis ash bin (202), a flue gas outlet of the pyrolysis furnace (201) forms an exhaust end of the pyrolysis unit (200), and the system further comprises a first induced draft fan (203), an inlet of the first induced draft fan (203) is communicated with a product gas outlet of the carbon capturing device (303), and an outlet of the first induced draft fan (203) is communicated with an air inlet of the pyrolysis furnace (201) for pressurizing carbon dioxide protection gas obtained by carbon capturing into the pyrolysis furnace (201).
4. A system according to claim 3, characterized in that the shielding gas supply unit (300) comprises a spray tower (301), a first dust separator (302) and a carbon capture device (303) which are in turn connected in the flue gas flow direction; the flue gas inlet of the spray tower (301) is communicated with the flue gas outlet of the household garbage incinerator, the solid outlet of the spray tower (301) is communicated with the inlet of the raw ash bin (101), the flue gas outlet of the spray tower (301) is communicated with the flue gas inlet of the first dust remover (302), and the solid outlet of the first dust remover (302) is communicated with the inlet of the raw ash bin (101).
5. The system of claim 4, wherein the flue gas cleaning unit (400) comprises a second dust collector (401), a second induced draft fan (402), a scrubber (403), an alkaline scrubber (404), a gas-water separator (405), an activated carbon device (406), an electric heating device (407), an oxidation catalytic device (408), an SCR denitration device (409), a mercury removal module (410) and a third induced draft fan (411) which are sequentially communicated in a flue gas flow direction; The flue gas inlet of the second dust remover (401) is communicated with the flue gas outlet of the pyrolysis furnace (201); the gas outlet of the third induced draft fan (411) is divided into a circulating recycling branch and a standard discharge branch, the circulating recycling branch is communicated with the carbon trapping device (303) and is used for recycling the purified flue gas rich in carbon dioxide, and the standard discharge branch is used for discharging standard flue gas; Wherein, the circulation recycling branch road and the on-off and flow adjustable setting of discharge branch road up to standard.
6. The system according to claim 5, characterized in that the second dust separator (401) is provided with a dust discharge opening, the system further comprising a return conduit, one end of which is connected to the dust discharge opening and the other end to the feed opening of the mixer (103) or to the feed opening of the feed bin (104).
7. The system according to claim 5, characterized in that the shielding gas supply unit (300) further comprises a chimney (304), the flue gas outlet of the first dust catcher (302) is divided into a discharge branch and a carbon capture branch, the discharge branch is communicated to the chimney (304), the carbon capture branch is communicated to the carbon capture device (303), the product gas outlet of the carbon capture device (303) is communicated with the gas inlet of the pyrolysis furnace (201) through the first induced draft fan (203) for sending captured carbon dioxide as pyrolysis shielding gas into the pyrolysis furnace (201), and the decarbonized tail gas outlet of the carbon capture device (303) is communicated with the gas inlet of the chimney (304).
8. A low-temperature pyrolysis flue gas coupling treatment method for household garbage incineration fly ash, which is characterized by adopting the household garbage incineration fly ash low-temperature pyrolysis flue gas coupling treatment system as claimed in any one of claims 1 to 7, and comprising the following steps: s1, pre-treating fly ash, namely mixing fly ash generated by incineration of household garbage with an additive and carrying out mixing treatment to obtain a mixed material; S2, obtaining a protective gas, namely, receiving flue gas of a garbage incineration system, pretreating, and then capturing carbon to obtain CO 2 , wherein CO 2 is used as a pyrolysis protective gas; S3, pyrolysis reaction, namely synchronously feeding the mixed material and the shielding gas into a pyrolysis unit (200), controlling the mixed material and the shielding gas to flow in the same direction in the pyrolysis unit (200) and carrying out low-temperature pyrolysis reaction to generate pyrolysis ash and pyrolysis flue gas; s4, purifying the flue gas, namely sending the pyrolysis flue gas into a flue gas purifying unit (400) for multistage purification treatment, and recycling the purified flue gas rich in carbon dioxide to a carbon trapping process, wherein the flue gas reaching the standard is directly discharged.
9. The method of claim 8, wherein in the fly ash pretreatment step, the additive comprises at least one of sodium sulfide or sodium hydrogen phosphate, and the mass ratio of the fly ash to the additive is controlled to be 1:0.02 to 1:0.05.
10. The method according to claim 8, characterized in that the flue gas cleaning step comprises in particular: S41, removing dust in the pyrolysis flue gas through a second dust remover (401); s42, removing heavy metals and part of acid gas through wet washing; S43, removing residual acid gas through alkali washing; s44, removing moisture through a dehumidifying device; s45, adsorbing heavy metals and dioxin through an adsorption device; S46, raising the temperature of the flue gas by a heating device; S47, removing CO through catalytic oxidation reaction, removing nitrogen oxides through selective catalytic reduction reaction, and removing mercury through mercury removal treatment.

Description

Low-temperature decoupling flue gas treatment system and method for household garbage incineration fly ash Technical Field The invention belongs to the field of treatment of household garbage incineration fly ash, and relates to a low-temperature decoupling flue gas treatment system and method for the household garbage incineration fly ash. Background With the acceleration of the urban process and the growth of population, the yield of household garbage is continuously increased, and garbage incineration is widely applied as an efficient treatment mode. However, fly ash generated in the garbage incineration process contains harmful substances such as dioxin, heavy metals and soluble salts, and is classified as dangerous waste by the national environmental protection department, and the hazardous waste can be recycled or safely disposed after harmless treatment. According to the standard of the technical specification (trial) HJ1134-2020 for pollution control of household garbage incineration fly ash issued in 2020, the recycling utilization of the fly ash needs to meet three conditions, namely, the content of the soluble chlorine in ① should not exceed 2%, preferably not higher than 1%, the leaching concentration of the heavy metal in ② fly ash treatment products should not exceed the maximum allowable emission concentration limit value specified in GB 8978, and the total amount of ③ dioxin residues should not exceed 50ng-TEQ/kg (calculated by dry weight of the fly ash). The current effective method for dioxin treatment is pyrolysis at a temperature above 850 ℃ or low-temperature degradation below 500 ℃. High pyrolysis energy consumption, and high construction cost and operation cost. The low-temperature thermal degradation treatment condition is mild, the temperature is low, the energy consumption is low, the process is simple, the facility construction and operation cost is low, and the experiment has verified that the method is reliable, so that the method is widely focused. In the existing low-temperature pyrolysis treatment technology of fly ash, the pyrolysis process needs to be performed in an anoxic or low-oxygen environment to prevent the combustion reaction of organic matters in the fly ash, so that protective gas needs to be introduced into the pyrolysis furnace to maintain an inert atmosphere. The prior art generally employs a separate shielding gas supply device, such as a nitrogen generator or an inert gas storage tank, to provide shielding gas to the pyrolysis furnace. Meanwhile, the flue gas generated in the pyrolysis process needs to be independently configured with a purification system for treatment. However, the above prior art has the following drawbacks: The method can not strengthen the solidification of heavy metals by utilizing the chemical characteristics of flue gas, wherein nitrogen shielding gas in the prior art is inert gas, can not chemically react with components in fly ash, can not solidify heavy metals through chemical reaction or reduce volatilization of heavy metals, and the solidification of heavy metals mainly depends on a subsequent water washing process, so that the dosage of the medicament is large. The pollutant source reduction effect is poor, namely in the pyrolysis process, pollutants such as NO x、NH3, CO, HCl, heavy metal Hg and the like in the flue gas mainly depend on the treatment of a rear-end purification system, and the lack of source reduction measures leads to high load and high running cost of the rear-end purification system. The energy utilization efficiency is low, the protective gas in the prior art is usually at normal temperature, and needs to be additionally heated after entering the pyrolysis furnace, so that the power consumption of the pyrolysis furnace is increased, and meanwhile, the fly ash pyrolysis system and the garbage incineration system are separately designed, so that the flue gas waste heat resources generated by the garbage incineration system cannot be fully utilized. The system integration level is low, the existing fly ash pyrolysis system and the garbage incineration system independently operate, the pyrolysis flue gas purification system is also independently configured, and the pyrolysis flue gas purification system and the incineration system cannot cooperate, so that equipment is repeatedly invested, the integrated system integration level is low, and the resource utilization efficiency is low. Therefore, how to utilize the waste heat and chemical characteristics of the incinerator flue gas to strengthen heavy metal solidification and pollutant source reduction, and to realize effective coupling of fly ash pyrolysis treatment and a garbage incineration system, so as to improve the resource utilization efficiency, becomes a technical problem to be solved in the field. Disclosure of Invention In view of the above, the invention provides a low-temperature pyrolysis flue gas coupling treatment system and a low-temperature pyrol