CN114877344A - System and method for continuously treating dioxin in fly ash - Google Patents
System and method for continuously treating dioxin in fly ash Download PDFInfo
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- CN114877344A CN114877344A CN202210624514.9A CN202210624514A CN114877344A CN 114877344 A CN114877344 A CN 114877344A CN 202210624514 A CN202210624514 A CN 202210624514A CN 114877344 A CN114877344 A CN 114877344A
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- 239000010881 fly ash Substances 0.000 title claims abstract description 157
- 238000000034 method Methods 0.000 title claims abstract description 33
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 title claims abstract 22
- 238000003860 storage Methods 0.000 claims abstract description 14
- 238000001035 drying Methods 0.000 claims abstract description 11
- 238000007599 discharging Methods 0.000 claims abstract description 7
- 239000004568 cement Substances 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 230000000694 effects Effects 0.000 claims description 5
- 238000005469 granulation Methods 0.000 claims description 5
- 230000003179 granulation Effects 0.000 claims description 5
- 239000000779 smoke Substances 0.000 claims description 4
- 238000000354 decomposition reaction Methods 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims description 3
- 238000011017 operating method Methods 0.000 claims 1
- 239000007789 gas Substances 0.000 abstract description 67
- 238000010438 heat treatment Methods 0.000 abstract description 7
- 239000002245 particle Substances 0.000 abstract description 6
- 239000002699 waste material Substances 0.000 abstract description 4
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- 238000001816 cooling Methods 0.000 abstract description 2
- 238000005054 agglomeration Methods 0.000 abstract 1
- 230000002776 aggregation Effects 0.000 abstract 1
- 239000002912 waste gas Substances 0.000 abstract 1
- KVGZZAHHUNAVKZ-UHFFFAOYSA-N 1,4-Dioxin Chemical compound O1C=COC=C1 KVGZZAHHUNAVKZ-UHFFFAOYSA-N 0.000 description 72
- 238000005516 engineering process Methods 0.000 description 9
- 239000007787 solid Substances 0.000 description 7
- 239000000428 dust Substances 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 230000015556 catabolic process Effects 0.000 description 5
- 238000006731 degradation reaction Methods 0.000 description 5
- 239000003546 flue gas Substances 0.000 description 5
- 238000004321 preservation Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 229920000742 Cotton Polymers 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 3
- 238000006065 biodegradation reaction Methods 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 238000004056 waste incineration Methods 0.000 description 3
- 235000019738 Limestone Nutrition 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 150000002013 dioxins Chemical class 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- 239000006028 limestone Substances 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 238000000197 pyrolysis Methods 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 206010021143 Hypoxia Diseases 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000010882 bottom ash Substances 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 238000006298 dechlorination reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 239000002920 hazardous waste Substances 0.000 description 1
- 230000001146 hypoxic effect Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 238000000120 microwave digestion Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 238000010791 quenching Methods 0.000 description 1
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- 239000002994 raw material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000009284 supercritical water oxidation Methods 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G5/00—Incineration of waste; Incinerator constructions; Details, accessories or control therefor
- F23G5/44—Details; Accessories
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
- F27B7/12—Rotary-drum furnaces, i.e. horizontal or slightly inclined tiltable
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
- F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
- F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
- F27B7/36—Arrangements of air or gas supply devices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G2209/00—Specific waste
- F23G2209/30—Solid combustion residues, e.g. bottom or flyash
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention belongs to the field of waste disposal, and particularly relates to a system and a method for continuously disposing dioxin in fly ash. Comprises a fly ash storage bin, a fly ash dioxin removing unit, a tail gas conveying pipeline and a tail gas disposal unit which are connected in sequence; the unit for removing dioxin from fly ash comprises a rotary kiln, wherein the fly ash is heated and removed in two stages at the temperature of 350-650 ℃: firstly, drying the fly ash until the moisture content is less than 0.3%, avoiding the fly ash from forming large particles or being not beneficial to removing dioxin due to moisture existence or agglomeration in the rotation process, then heating to 350-650 ℃ to remove dioxin, conveying the treated tail gas to a tail gas treatment unit for high-temperature treatment, thoroughly removing dioxin possibly carried or generated again in the tail gas, and discharging a fly ash treatment product from the tail end of the rotary kiln. The invention does not need anoxic environment, rapid cooling and intermittent conditions, and can realize continuous treatment of fly ash by air, waste gas and other gases.
Description
Technical Field
The invention belongs to the field of waste disposal and resource utilization, and particularly relates to a system and a method for continuously disposing dioxin in fly ash.
Background
The household garbage incineration fly ash is generated in the municipal household garbage incineration process, and organic matters in the garbage are mainly discharged in the form of gaseous substances in the garbage incineration process; the inorganic substances mainly form solid particles, wherein large-particle solids are deposited on the bottom of the incinerator and a fire grate and are called bottom ash, while fine particles float in the flue gas and enter a flue gas purification system along with the flue gas, the particles form 50% of incineration fly ash, the rest incineration fly ash is derived from limestone or active carbon added in the flue gas purification process, the limestone or active carbon and the active carbon are captured and collected in a dust collector (an electrostatic dust collector, a cloth bag dust collector and the like), meanwhile, a part of fine particles are settled down at the bottom of a flue and a chimney, and the captured and settled fine particles are called incineration fly ash.
Fly ash contains trace heavy metals such as dioxin, Cr, Hg and the like, and is listed in the national hazardous waste record (coded as HW 18). In recent years, the increment of household garbage is large, and the garbage incineration power generation industry is increased year by year, so that the fly ash amount is increased rapidly. The fly ash is one of main carriers of dioxin pollution, and researches show that the PCDD/Fs concentration and toxicity equivalent in the fly ash have larger difference according to different factors such as incineration waste types, incineration furnace types, incineration capacity, dust removal equipment and the like, and about half of the total amount of dioxin generated by an incineration source comes from the fly ash.
The treatment technology of the dioxin in the fly ash mainly comprises solidification and landfill, low-temperature pyrolysis, high-temperature treatment, biodegradation, chemical removal and the like. The stabilization solidification and landfill do not degrade the dioxin in the fly ash, but the dioxin is sealed and stored, and the landfill is a potential dioxin discharge source for the nearby water environment. The degradation of dioxin can be realized by the technology of cooperatively treating fly ash by high-temperature melting and a cement kiln, but the energy consumption and the cost are too high in a melting mode, so that the economic value is low. The treatment technology mainly adopted in China is a curing landfill method and a cement kiln cooperative treatment technology. Other techniques such as biodegradation, chemical removal and low temperature pyrolysis are currently mostly in the laboratory or pilot plant stage. The biodegradation method has the advantages of environmental friendliness, low cost and the like, but the dioxin degradation efficiency is relatively low; the chemical removal method can thoroughly treat wastes, and the most studied treatment technologies comprise an oxidation-reduction dechlorination method, a photodegradation method, a catalytic oxidation method, a mechanical ball milling method, a microwave digestion method, a supercritical water oxidation method and the like.
At present, the common prior art in the field of the technology of co-processing fly ash by a cement kiln is as follows: chloride ions which have serious limitations (crusting, product quality and the like) on cement production are removed in advance through washing, and then the washed fly ash is put into a high-temperature area of a cement kiln for incineration disposal, so that the aims of degrading dioxin in the fly ash and solidifying heavy metals are fulfilled. The technology introduces fly ash additive, which may reduce the dosage of cement raw material, and simultaneously adopts bypass air release technology to avoid the crust blockage caused by the circulation and enrichment of chloride ions in the kiln, so that about 6-10% of flue gas with more than 1000 ℃ is led out through the bypass air release, which increases the energy consumption.
Low temperature heat treatment degradation was first proposed by Hagenmaier who thought that the following conditions had to be met in order to ensure effective degradation of dioxins: (1) (ii) hypoxic conditions; (2) the reaction temperature is between 250 ℃ and 400 ℃; (3) the retention time is 1 h; (4) the discharge temperature is below 60 ℃. The defect is that the anaerobic environment restricts the continuous disposal, and the continuous disposal is generally carried out in a closed reaction kettle in a batch mode.
In summary, the problems of the prior art are:
(1) the fly ash can be treated on a large scale only after the fly ash is subjected to water washing pretreatment to remove chloride ions in the synergistic treatment of the cement kiln, and the energy consumption of a system is increased due to the fact that bypass air release is increased in the synergistic treatment process.
(2) The low-temperature heat treatment degradation requires strict anoxic environment and tail gas quenching, and is an intermittent treatment.
Disclosure of Invention
In order to solve the above technical problems in the prior art, a first object of the present invention is to provide a system for continuously treating dioxin in fly ash, which includes a fly ash storage bin, a fly ash dioxin removal unit, a tail gas delivery pipeline and a tail gas treatment unit, which are connected in sequence;
the bottom of the fly ash storage bin is provided with a vibrating device to facilitate fly ash blanking; the fly ash dioxin removal unit is used for carrying out drying intervention treatment on the fly ash and removing dioxin in the fly ash; the unit comprises a rotary kiln, wherein a feed end of the rotary kiln is connected with a hot air pipeline so as to heat the rotary kiln and remove dioxin by using hot air; an annular baffle is fixed on the side of the feeding end in the rotary kiln to ensure that the fly ash is prevented from flowing back to the kiln head of the rotary kiln to form a dead zone in the process of discharging the fly ash into the rotary kiln; the fly ash in the fly ash storage bin is conveyed to the inner side of a baffle plate of the rotary kiln under the action of gravity and vibration equipment through an inclined pipeline, and the tail end of the pipeline is a fly ash discharge port; the effective length of the rotary kiln meets the condition that L is more than or equal to a +1120Rnsin theta so as to meet the necessary retention time for removing dioxin from the fly ash, and the effective length refers to the length from a fly ash discharge port to the position where the fly ash leaves the rotary kiln; wherein: a-the horizontal distance between the baffle and the fly ash discharge port, wherein a is more than or equal to 100mm and less than or equal to 300 mm; r-the inner diameter of the rotary kiln, wherein R is more than or equal to 1m and less than or equal to 3 m; n-the rotating speed of the rotary kiln, wherein n is more than or equal to 3r/min and less than or equal to 5 r/min; theta is the inclination angle of the rotary kiln, sin theta is more than or equal to 0.03 and less than or equal to 0.05; a gas outlet of the rotary kiln is connected with a tail gas disposal unit through a tail gas conveying pipeline, and the gas outlet is arranged on one side opposite to the feeding end;
the tail gas treatment unit comprises one of a cement kiln, a kiln head, a decomposing furnace, a smoke chamber or a garbage incinerator hearth with the temperature of above 850 ℃, the fly ash tail gas treated by the fly ash dioxin removal unit is conveyed to the tail gas treatment unit through the tail gas conveying pipeline for high-temperature treatment, and a fly ash treatment product is discharged from the tail end of the rotary kiln.
Furthermore, the ratio of the area of the baffle to the cross-sectional area of the rotary kiln is 0.8-0.85.
Another object of the present invention is to provide a method for operating the system for continuously treating dioxin in fly ash, which comprises the following steps:
s1, feeding the fly ash with the dioxin concentration of 400-;
s2, the initial kiln speed of the rotary kiln is zero, the drying temperature is controlled at 110 ℃ below 100 ℃, and the moisture in the fly ash is dried to be below 0.3 percent so as to avoid the influence of granulation on the subsequent dioxin removal effect in the rotation process of the fly ash;
s3, after the feeding is finished, continuously introducing hot air into the feed end of the rotary kiln, and fully contacting the hot air with the fly ash in a forward flow manner at a speed of 0.2-2 m/S; raising the temperature in the rotary kiln to 350-650 ℃;
s4, removing most of the dioxin carried by the fly ash in the rotary kiln, and conveying the dioxin carried by the tail of the fly ash or possibly regenerated together with the tail gas to a tail gas treatment unit at 850 ℃ through a tail gas conveying pipeline for high-temperature treatment;
s5, controlling the temperature difference between the rotary kiln gas outlet and the water decomposition furnace within 20-50 ℃ by increasing the gas flow rate or adding heat preservation cotton outside the tail gas conveying pipeline, and avoiding that dioxin formed by overlarge temperature difference is deposited in the tail gas conveying pipeline and cannot be treated;
after treatment, the dioxin concentration in the fly ash is reduced to 20-50 ngTEQ/kg.
The invention has the advantages and positive effects that:
compared with the prior art, the system and the method for continuously treating the dioxin in the fly ash avoid the limitation that the fly ash needs to be washed by water and the chlorine content of more than 20 percent is reduced to below 1 percent in the cement kiln cooperation treatment fly ash technology, so that the dioxin in the fly ash is removed. Meanwhile, the existing cement kiln facilities are utilized, and energy consumption measures such as blowing cold air or water cooling brought by the discharge temperature of lower than 60 ℃ are not required to be increased. This patent is simple and convenient, gets rid of dioxin unit, tail gas pipeline and tail gas through the flying dust and handles the unit and can realize that the flying dust is dealt with in the continuous type.
The method comprises the steps of performing two-stage heating in a rotary kiln (firstly, drying the fly ash until the moisture content is less than 0.3%, avoiding the situation that the fly ash has moisture in the rotating process to form large particles which are not beneficial to removing dioxin, and then heating to 350-650 ℃ to remove the dioxin); on the other hand, the dioxin is slightly degraded at a certain temperature, the tail part has the possibility of being synthesized again, and the dioxin generated again at the tail part or carried by the airflow is sent into a high-temperature area above 850 ℃ to be thoroughly decomposed. And the hot air flow disturbs the fly ash under a certain temperature condition in the rotary kiln, so that the bonding force between the fly ash and the dioxin is reduced or eliminated, and the dioxin on the surface of the fly ash is activated again and is taken away in an air flow mode. Limiting the temperature difference between the outlet of the rotary kiln and the inlet of the tail gas treatment unit to be 20-50 ℃ through gas speed increasing or external heat preservation, and preventing dioxin from forming solids to be deposited in a pipeline; (the tail gas is burnt in a high-temperature area of the tail gas disposal unit to completely degrade the dioxin.
Description of the drawings:
FIG. 1 is a schematic view of a system for continuously disposing dioxin in fly ash according to the present invention;
in the figure; 1. a fly ash storage bin; 2. a rotary kiln; 21. a feeding end; 22. a gas outlet; 23. an annular baffle; 24. a fly ash discharge port; 3. a hot air duct; 4. a tail gas conveying pipeline; 5. a tail gas treatment unit; 6. a fly ash treatment product; 7. a pipeline.
Detailed Description
The technical scheme in the embodiment of the invention is clearly and completely described below; obviously; the described embodiments are only some of the embodiments of the invention; rather than all embodiments. Based on the embodiments of the invention; all other embodiments obtained by a person skilled in the art without making any inventive step; all fall within the scope of protection of the present invention.
Example 1
The embodiment provides a system for continuously treating dioxin in fly ash, which comprises a fly ash storage bin, a fly ash dioxin removing unit, a tail gas conveying pipeline and a tail gas treatment unit, which are sequentially connected; the lower part of the fly ash storage bin is provided with a vibrating device to facilitate blanking; the fly ash dioxin removal unit is used for carrying out drying intervention treatment on the fly ash and removing dioxin in the fly ash; the unit comprises a rotary kiln 2, wherein a feed end 21 of the rotary kiln is connected with a hot air pipeline 3 through a flange so as to heat the rotary kiln; an annular baffle plate 23 is fixed on the side of the feeding end in the rotary kiln, the fly ash in the fly ash storage bin 1 is conveyed to the inner side of the baffle plate of the rotary kiln 2 through an inclined pipeline 7 under the action of gravity and vibration equipment, and the tail end of the pipeline is a fly ash discharging port; the effective length of the rotary kiln meets the condition that L is more than or equal to a +1120Rnsin theta, and the effective length refers to the length from a fly ash discharge port to the position where the fly ash leaves the rotary kiln; wherein: the horizontal distance between the a-baffle and the fly ash discharge port is more than or equal to 100mm and less than or equal to 300mm, so that the fly ash is prevented from flowing back to the feed end to cause dead zones; r-the inner diameter of the rotary kiln, wherein R is more than or equal to 1m and less than or equal to 3 m; n-the rotating speed of the rotary kiln, wherein n is more than or equal to 3r/min and less than or equal to 5 r/min; theta is the inclination angle of the rotary kiln, sin theta is more than or equal to 0.03 and less than or equal to 0.05; a gas outlet 22 of the rotary kiln is connected with a tail gas treatment unit 5 through a tail gas conveying pipeline 4, and the gas outlet 22 is arranged on the side opposite to the feeding end 21;
the tail gas treatment unit 5 comprises one of a cement kiln, a kiln head, a decomposing furnace, a smoke chamber or a hearth of a garbage incinerator with the temperature of above 850 ℃, the fly ash tail gas treated by the fly ash dioxin removing unit is conveyed to the tail gas treatment unit through the tail gas conveying pipeline for high-temperature treatment, and a fly ash treatment product 6 is discharged from the tail end of the rotary kiln.
Example 2:
the method for removing dioxin from waste incineration fly ash by using the system in the embodiment 1 comprises the following steps:
s1, feeding the fly ash with the dioxin concentration of 500ngTEQ/kg in the fly ash storage bin into the rotary kiln through an inclined pipeline;
s2, the initial kiln speed of the rotary kiln is zero, the drying temperature is controlled at 110 ℃, and the moisture in the fly ash is dried to be below 0.3 percent so as to avoid the influence of granulation on the subsequent dioxin removal effect in the rotation process of the fly ash;
s3, after the feeding is finished, continuously introducing hot air into the feed end of the rotary kiln, wherein the hot air has no special requirement on the components and is in full forward flow contact with the fly ash at the speed of 0.2 m/S; the temperature in the rotary kiln is raised to 350 ℃, the effective length of the rotary kiln meets the condition that L is more than or equal to a +1120Rnsin theta, and the horizontal distance a between a baffle and a fly ash discharge port is 100 mm; the inner diameter R of the rotary kiln is 1 m; the kiln speed n of the rotary kiln is 5 r/min; the inclination angle theta of the rotary kiln meets the requirement that sin theta is 0.03;
s4, the inner diameter of the baffle is 50mm, and the ratio of the area of the baffle to the cross-sectional area of the rotary kiln is 0.80, so that on the basis of not influencing the feeding of the fly ash, the fly ash is prevented from flowing back to the feeding end to cause a dead zone;
s5, removing most of dioxin carried by the fly ash in the rotary kiln, and conveying the dioxin carried by the tail of the fly ash or possibly generated again to a cement kiln at 850 ℃ along with tail gas through a tail gas conveying pipeline for high-temperature treatment; the temperature difference between the gas outlet of the rotary kiln and the water decomposing furnace is controlled within 20 ℃ by means of increasing the gas flow rate or adding heat preservation cotton outside the tail gas conveying pipeline, so that the phenomenon that dioxin is formed into solid and deposited in the tail gas conveying pipeline and cannot be treated due to overlarge temperature difference is avoided;
after treatment, the dioxin concentration in the fly ash was reduced to 50 ngTEQ/kg.
Example 3:
the method for removing dioxin from waste incineration fly ash by using the system in the embodiment 1 comprises the following steps:
s1, feeding the fly ash with the dioxin concentration of 450ngTEQ/kg in the fly ash storage bin into the rotary kiln through an inclined pipeline;
s2, the initial kiln speed of the rotary kiln is zero, the drying temperature is controlled at 105 ℃, and the moisture in the fly ash is dried to be below 0.3 percent so as to avoid the influence of granulation on the subsequent dioxin removal effect in the rotation process of the fly ash;
s3, after the feeding is finished, continuously introducing hot air into the feed end of the rotary kiln, wherein the hot air has no special requirement on the components, and the gas is fully contacted with the fly ash in a downstream manner at the speed of 1 m/S; the temperature in the rotary kiln is raised to 500 ℃, the effective length of the rotary kiln meets the condition that L is more than or equal to a +1120Rnsin theta, and the horizontal distance a between a baffle and a fly ash discharge port is 300 mm; the inner diameter R of the rotary kiln is 3 m; the kiln speed n of the rotary kiln is 3 r/min; the inclination angle theta of the rotary kiln meets the requirement that sin theta is 0.04;
s4, the inner diameter of the annular baffle is 80mm, and the ratio of the area of the baffle to the cross-sectional area of the rotary kiln is 0.85, so that on the basis of not influencing the feeding of the fly ash, the fly ash is prevented from flowing back to the feeding end to cause a dead zone;
s5, removing most of dioxin carried by the fly ash in the rotary kiln, conveying the dioxin carried by the tail of the fly ash or possibly generated again to a decomposition furnace at 850 ℃ along with the tail gas through a tail gas conveying pipeline for high-temperature treatment, and discharging a fly ash treatment product 6 from the tail end of the rotary kiln; the temperature difference between the gas outlet of the rotary kiln and the water decomposing furnace is controlled within 30 ℃ by means of increasing the gas flow rate or adding heat preservation cotton outside the tail gas conveying pipeline, so that the phenomenon that dioxin is formed into solid and deposited in the tail gas conveying pipeline and cannot be treated due to overlarge temperature difference is avoided;
after treatment, the dioxin concentration in the fly ash was reduced to 35 ngTEQ/kg.
Example 4:
the method for removing dioxin from waste incineration fly ash by using the system in the embodiment 1 comprises the following steps:
s1, feeding the fly ash with the dioxin concentration of 400ngTEQ/kg in the fly ash storage bin into the rotary kiln through an inclined pipeline;
s2, the initial kiln speed of the rotary kiln is zero, the drying temperature is controlled at 100 ℃, and the moisture in the fly ash is dried to be below 0.3 percent so as to avoid the influence of granulation on the subsequent dioxin removal effect in the rotation process of the fly ash;
s3, after the feeding is finished, continuously introducing hot air into the feed end of the rotary kiln, wherein the hot air has no special requirement on the component, and the gas is fully contacted with the fly ash in a downstream manner at the speed of 2 m/S; the temperature in the rotary kiln is raised to 650 ℃, the effective length of the rotary kiln meets the condition that L is more than or equal to a +132Rntan theta, and the distance a between a baffle and a fly ash discharge port is 200 mm; the inner diameter R of the rotary kiln is 2 m; the kiln speed n of the rotary kiln is 3 r/min; the inclination angle theta of the rotary kiln meets the requirement that sin theta is 0.05;
s4, the inner diameter of the baffle is 100mm, and the ratio of the area of the baffle to the cross-sectional area of the rotary kiln is 0.80, so that on the basis of not influencing the feeding of the fly ash, the fly ash is prevented from flowing back to the feeding end to cause a dead zone;
s5, removing most of dioxin carried by the fly ash in the rotary kiln, conveying the dioxin carried by the tail of the fly ash or possibly generated again to a smoke chamber at 850 ℃ along with the tail gas through a tail gas conveying pipeline for high-temperature treatment, and discharging a fly ash treatment product 6 from the tail end of the rotary kiln; the temperature difference between the gas outlet of the rotary kiln and the water decomposing furnace is controlled within 50 ℃ by means of increasing the gas flow rate or adding heat insulation cotton outside the tail gas conveying pipeline, so that the phenomenon that dioxin is formed into solid and deposited in the tail gas conveying pipeline and cannot be treated due to overlarge temperature difference is avoided;
after treatment, the dioxin concentration in the fly ash was reduced to 20 ngTEQ/kg.
The working principle is as follows:
the method comprises the steps of performing two-stage heating in a rotary kiln (firstly, drying the fly ash until the moisture content is less than 0.3%, avoiding the situation that the fly ash has moisture in the rotating process to form large particles which are not beneficial to removing dioxin, and then heating to 350-650 ℃ to remove the dioxin); on the other hand, the dioxin is slightly degraded at a certain temperature, the tail part has the possibility of being synthesized again, and the dioxin generated again at the tail part or carried by the airflow is sent into a high-temperature area above 850 ℃ to be thoroughly decomposed. And the hot air flow disturbs the fly ash under a certain temperature condition in the rotary kiln, so that the bonding force between the fly ash and the dioxin is reduced or eliminated, and the dioxin on the surface of the fly ash is activated again and is taken away in an air flow mode. Limiting the temperature difference between the outlet of the rotary kiln and the inlet of the tail gas treatment unit to be 20-50 ℃ through gas speed increasing or external heat preservation, and preventing dioxin from forming solids to be deposited in a pipeline; and burning the tail gas in a high-temperature area of the tail gas treatment unit to completely degrade dioxin.
The present invention is not limited to the above embodiments, but the present invention is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.
Claims (3)
1. A system for continuously treating dioxin in fly ash is characterized in that: the system comprises a fly ash storage bin, a fly ash dioxin removing unit, a tail gas conveying pipeline and a tail gas disposal unit which are connected in sequence;
the bottom of the fly ash storage bin is provided with a vibrating device to facilitate fly ash blanking; the fly ash dioxin removal unit is used for carrying out drying intervention treatment on the fly ash and removing dioxin in the fly ash; the unit comprises a rotary kiln, wherein a feed end of the rotary kiln is connected with a hot air pipeline so as to heat the rotary kiln and remove dioxin by using hot air; an annular baffle is fixed on the side of the feeding end in the rotary kiln, the fly ash in the fly ash storage bin is conveyed to the inner side of the baffle of the rotary kiln under the action of gravity and vibration through an inclined pipeline, and the tail end of the pipeline is a fly ash discharging port; the effective length of the rotary kiln meets the condition that L is more than or equal to a +1120Rnsin theta, and the effective length refers to the length from a fly ash discharge port to the position where the fly ash leaves the rotary kiln; wherein: a-the horizontal distance between the baffle and the fly ash discharge port, wherein a is more than or equal to 100mm and less than or equal to 300 mm; r-the inner diameter of the rotary kiln, wherein R is more than or equal to 1m and less than or equal to 3 m; n-the rotating speed of the rotary kiln, wherein n is more than or equal to 3r/min and less than or equal to 5 r/min; theta is the inclination angle of the rotary kiln, sin theta is more than or equal to 0.03 and less than or equal to 0.05; a gas outlet of the rotary kiln is connected with a tail gas disposal unit through a tail gas conveying pipeline, and the gas outlet is arranged on one side opposite to the feeding end;
the tail gas treatment unit comprises one of a cement kiln, a kiln head, a decomposing furnace, a smoke chamber or a garbage incinerator hearth with the temperature of above 850 ℃, and the fly ash tail gas treated by the fly ash dioxin removal unit is conveyed to the tail gas treatment unit through the tail gas conveying pipeline for high-temperature treatment.
2. The system for continuously disposing dioxin in fly ash according to claim 1, wherein: the ratio of the area of the baffle to the cross-sectional area of the rotary kiln is 0.8-0.85.
3. The operating method of the system for continuously disposing dioxin in fly ash according to claim 1, comprising the steps of:
s1, feeding the fly ash with the dioxin concentration of 400-;
s2, the initial kiln speed of the rotary kiln is zero, the drying temperature is controlled at 110 ℃ below 100 ℃, and the moisture in the fly ash is dried to be below 0.3 percent so as to avoid the influence of granulation on the subsequent dioxin removal effect in the rotation process of the fly ash;
s3, after the feeding is finished, continuously introducing hot air into the feed end of the rotary kiln, and fully contacting the gas with the fly ash in a forward flow manner at a speed of 0.2-2 m/S; raising the temperature in the rotary kiln to 350-650 ℃;
s4, removing most of the dioxin carried by the fly ash in the rotary kiln, conveying the dioxin carried by the tail of the fly ash or possibly regenerated dioxin along with tail gas to a tail gas treatment unit at 850 ℃ through a tail gas conveying pipeline for high-temperature treatment, and discharging a fly ash treatment product 6 from the tail end of the rotary kiln;
s5, controlling the temperature difference between the rotary kiln gas outlet and the water decomposition furnace within 20-50 ℃ to avoid that dioxin formed by overlarge temperature difference is deposited in a tail gas conveying pipeline and cannot be treated;
after treatment, the dioxin concentration in the fly ash is reduced to 20-50 ngTEQ/kg.
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| CN117920729A (en) * | 2024-03-21 | 2024-04-26 | 北京市弘洁蓝天科技股份有限公司 | Continuous degradation device for removing dioxin based on laser |
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| JP2679598B2 (en) * | 1993-11-04 | 1997-11-19 | 株式会社栗本鐵工所 | Method and equipment for removing dioxins from fly ash in a refuse incinerator |
| JP2004216289A (en) * | 2003-01-15 | 2004-08-05 | Kawasaki Giken Co Ltd | Method for heat dechlorination and decomposition of dioxin contained in incinerator fly ash and apparatus therefor |
| CN100494780C (en) * | 2003-02-20 | 2009-06-03 | 北京环能海臣科技有限公司 | System for erasing fly ash containing dioxin in refuse burning boiler by incineration |
| CN101569890B (en) * | 2009-05-25 | 2011-01-05 | 北京新北水水泥有限责任公司 | New disposal method of fly ash |
| CN201694958U (en) * | 2010-03-23 | 2011-01-05 | 北京新北水水泥有限责任公司 | Novel flying ash processing device |
| CN104058614B (en) * | 2014-07-02 | 2016-03-09 | 南京凯盛国际工程有限公司 | The system of cement kiln synergic processing house refuse |
| CN105910124B (en) * | 2016-06-16 | 2018-03-20 | 光大环保技术研究院（深圳）有限公司 | A kind of flying dust watery fusion device and method |
| CN111473346A (en) * | 2020-05-19 | 2020-07-31 | 天津中材工程研究中心有限公司 | System and method for removing dioxin in waste incineration fly ash in parallel connection with cement clinker production line |
| CN212157203U (en) * | 2020-05-19 | 2020-12-15 | 天津中材工程研究中心有限公司 | System for removing dioxin in waste incineration fly ash in parallel connection with cement clinker production line |
| CN113414215A (en) * | 2021-06-16 | 2021-09-21 | 中国恩菲工程技术有限公司 | Treatment method of incineration fly ash |
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| CN117920729A (en) * | 2024-03-21 | 2024-04-26 | 北京市弘洁蓝天科技股份有限公司 | Continuous degradation device for removing dioxin based on laser |
| CN117920729B (en) * | 2024-03-21 | 2024-05-24 | 北京市弘洁蓝天科技股份有限公司 | Continuous degradation device for removing dioxin based on laser |
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