CN114963783A - Electric furnace flue gas dry processing method - Google Patents

Electric furnace flue gas dry processing method Download PDF

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Publication number
CN114963783A
CN114963783A CN202210473648.5A CN202210473648A CN114963783A CN 114963783 A CN114963783 A CN 114963783A CN 202210473648 A CN202210473648 A CN 202210473648A CN 114963783 A CN114963783 A CN 114963783A
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flue gas
electric furnace
fine powder
temperature
smoke
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李庆春
许志伟
孙岩
许志豪
周峰明
肖亚娟
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Wuxi Hongqi Dust Collector Equipment Co Ltd
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Wuxi Hongqi Dust Collector Equipment Co Ltd
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Priority to CN202210473648.5A priority Critical patent/CN114963783A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/004—Systems for reclaiming waste heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/008—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases cleaning gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • 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
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Treating Waste Gases (AREA)

Abstract

The invention relates to a dry method for treating electric furnace flue gas, which comprises the following steps: 1) mixing, burning and settling the flue gas; 2) quenching flue gas; 3) dedusting flue gas; 4) the ash removal operation, namely the electric furnace flue gas dry treatment method, respectively extracts the flue gas of an electric furnace and a scrap steel continuous preheating mechanism for regulation and mixing, always keeps the temperature of the flue gas to be more than or equal to 800 ℃ in a combustion settling cylinder arranged behind the electric furnace under the action of an aerobic auxiliary burner, and stays in the mixed combustion settling cylinder for 2-3s, so that toxic substances such as dioxin, furan and the like contained in the flue gas are burnt and decomposed, and the standard emission of the flue gas is ensured.

Description

Electric furnace flue gas dry processing method
Technical Field
The invention relates to the field of flue gas treatment, in particular to a dry method treatment method for flue gas of an electric furnace.
Background
Currently, along with the increasing severity of the environmental pollution problem in China, the nation also gradually strengthens the attention on the environmental protection work, dioxin is an important environmental pollutant, is called the toxicity in the century, is a persistent organic pollutant naturally formed in the production stage, cannot control pollution by means of forbidden and production forbidden forms, and is listed as a key detection project.
The total amount of dioxin discharged by steel smelting in China accounts for about 40-45% of the total amount of dioxin discharged in China every year, and the dioxin is one of main emission sources, and the electric furnace steelmaking smoke dust is the main dioxin emission source except sintering smoke.
In recent years, the 'short-flow' steelmaking process is rapidly developed, a batch of ultrahigh-power electric furnaces are built in succession, and the smoke and dust amount is remarkably increased along with the increase of the steel yield of the electric furnaces. At present, the technological processes for purifying and utilizing the flue gas of each steel-making electric furnace are largely the same and slightly different, and only the collection mode of the flue gas, the cooling mode of the flue gas and the type of a bag-type dust collector are slightly different.
The CONSTEEL electric furnace and the quantum electric furnace are increasingly adopted by various iron and steel enterprises because scrap steel is continuously added and the waste heat of the recovered flue gas is fully utilized, thereby reducing the power consumption, saving the energy and reducing the cost. Has been adopted in China in a large amount. For the CONSTEEL electric furnace and the quantum electric furnace, whether the flue gas utilization and the purification system normally run or not directly relates to whether the electric furnace is produced smoothly or not; the energy consumption of the flue gas utilization and purification system is high and low, which is directly related to the high and low cost of electric furnace steel making.
The smelting process flow of the CONSTEEL electric furnace and the quantum electric furnace is shown in figure 1:
the generation mechanism of dioxin in the smelting process of the CONSTEEL electric furnace and the quantum electric furnace is as follows:
combining to generate: grease, paint, coating, plastics and the like brought by the steel scrap contain dioxin and dioxin precursors, and the dioxin precursors can be directly subjected to chemical combination reaction in the steel scrap preheating link to generate dioxin, wherein the reaction temperature range is 300-500 ℃.
② thermal decomposition reaction generation: in the process of preheating scrap steel or smelting in an electric furnace, the chlorine-containing high molecular compound is decomposed to generate dioxin through combustion/pyrolysis reaction, and the reaction temperature range is 500-800 ℃.
Thirdly, head-on synthesis: in the smelting process, after the temperature exceeds 800 ℃, dioxin can be thoroughly decomposed, but in the process of cooling flue gas, the dioxin can be generated again through elementary reaction, and the reaction temperature interval is 300-500 ℃.
The dioxin generated by the three ways flows through a combustion settling chamber, a mechanical air cooler or an evaporative cooler and other cooling devices along with the flue gas in sequence, is gradually cooled in a dust removal pipeline, and is finally discharged into a chimney through a bag-type dust remover.
By analyzing the generation mechanism of dioxin in the smelting process of the CONSTEEL electric furnace and the quantum electric furnace, the generation of the dioxin in the smelting process of the CONSTEEL electric furnace and the quantum electric furnace mainly has three types, namely, the combination reaction of raw materials, the thermal decomposition reaction in the combustion process and the de novo synthesis reaction in the temperature reduction process.
Based on the generation mechanism of dioxin in the smelting process of the CONSTEEL electric furnace and the quantum electric furnace, at present, domestic and foreign iron and steel enterprises mainly adopt three methods of source control, process control and terminal control to treat the dioxin, and main engineering application cases comprise four processes of a quenching process, an adsorption process, a catalytic degradation process, a secondary dust removal process and the like.
A source control method (scrap steel sorting pretreatment): the scrap steel is sorted and cleaned, and materials which can generate dioxin are prevented from entering the electric furnace. The method has strong operability and high feasibility. However, the effect is limited due to the limitation of raw materials.
The process control method comprises the following steps:
the method adopts a flue gas quenching method, rapidly cools the flue gas with the temperature of more than or equal to 800 ℃ to less than 200 ℃ within 2-3 seconds by adopting a quenching measure, and has a large number of enterprises applied at home and abroad at present. The method can obviously reduce the 'de novo synthesis' of the dioxin, but the method has the problems of higher equipment investment, incapability of recovering waste heat, more complex control, easy occurrence of bag pasting and smoke plume problems due to condensation and dewing, and in addition, the problem that the content of the dioxin discharged by flue gas does not reach the standard.
The end control method comprises the following steps: the method specifically comprises the following treatment methods:
firstly, the high-efficiency filtering technology is adopted, and the electric furnace flue gas is filtered and purified by adopting a physical filtering mode, so that the method is adopted by many enterprises at home and abroad. The method has the removal efficiency of more than or equal to 85 percent, but the smoke emission is difficult to reach the standard, and the collected fly ash causes secondary pollution.
Secondly, a physical adsorption method is adopted, which generally adopts a physical adsorption process (spraying an adsorbent) and combines a high-efficiency filtration technology, and a plurality of enterprises are also adopted at home and abroad. The method has the advantages of high removal efficiency,
the flue gas emission can reach the standard by more than or equal to 90-99%, but certain problems exist in the subsequent treatment of the adsorbent.
And thirdly, completely catalytically degrading the dioxin by adopting a catalytic decomposition method and using oxides of Ti, W, V and the like as catalysts. The process is still under development. The method has high removal efficiency, and the removal efficiency is not less than 97 ≥ E
99 percent, the flue gas emission can completely reach the standard, but the method has higher catalyst cost, easy poisoning and higher reaction temperature (about 300 ℃).
Fourthly, a low-temperature plasma processing method is adopted, and active radicals (OH, O, N, HO) can be generated by adopting low-temperature plasma discharge dissociation gas 2 、O 3 Etc.) and these active groups are capable of oxidizing dioxins. This method is currently in the process of development. The method has obvious effect of removing dioxin, but the plasma generator has high energy consumption, short service life and high cost of a high-power supply.
And fifthly, decomposing dioxin substances contained in the electric furnace smoke by adopting an ultraviolet photolysis method through ultraviolet irradiation on the electric furnace smoke. This method is currently in the process of development. The method can realize non-toxic, clean and efficient treatment of dioxin, but the technology is mature at present.
Because the dust-containing particle size of the flue gas of the electric furnace is smaller, the diameter of the flue gas is about 40-300 meshes, and the dust with the particle size can reach the standard only by adopting a bag-type dust collector to collect dust and discharge. However, in the electric furnace smelting stage, the temperature in the high-temperature flue reaches 1200 ℃, even though the temperature of the flue of the common dust remover is reduced, the temperature of the smoke gas still reaches 500 ℃ to 800 ℃ before entering the dust remover, obviously exceeds the allowable working temperature of the prior cloth bag dust remover, so the requirement on the dust remover is very high, and the emission cannot reach the environmental protection standard.
At present, the filtering of high-temperature flue gas is carried out in a working environment with a filter bag operating for a long time, and the temperature of the high-temperature flue gas is generally required to be reduced to be less than or equal to 200-250 ℃.
In order to effectively reduce the temperature of the flue gas and effectively eliminate toxic substances such as dioxin/furan and the like, the high-temperature flue gas purification treatment system flow commonly adopted at home and abroad in steel making by a CONSTEEL electric furnace and a quantum electric furnace at present is as follows: high-temperature smoke gas generated in the smelting process of the CONSTEEL electric furnace and the quantum electric furnace is preheated (about 450-650 ℃) → a combustion settling chamber → an evaporative cooler (rapid cooling) → a mixing tower (mixing with roof cover smoke to reduce smoke temperature) → a cloth bag type dust remover (filtering and purifying) → a fan → a chimney and discharging.
The steel-making dust removal system of the CONSTEEL electric furnace and the quantum electric furnace at present has the following defects:
1. the smoke temperature of a continuous steel scrap preheating system of a CONSTEEL electric furnace and a quantum electric furnace is sometimes low (450-650 ℃ is less than 800 ℃), because each steel enterprise pursues electric furnace steelmaking power consumption indexes and higher steel scrap preheating temperature, the temperature entering a quenching device is generally not high (450-650 ℃ is less than 800 ℃), much dioxin is not fully incinerated and decomposed and is still remained in the smoke of the electric furnace, and the quenching device cannot eliminate toxic substances of the dioxin. The dioxin in the flue gas of the electric furnace can not be reliably and stably removed by adopting an evaporative cooler (quenching and cooling) + a bag-type/filter cartridge type dust remover to purify and treat the flue gas, and the dioxin content in the flue gas discharged by the electric furnace can not be ensured to reach the standard.
2. In order to ensure that harmful substances such as dioxin/furan and the like contained in the flue gas of the CONSTEEL electric furnace and the quantum electric furnace are completely incinerated and decomposed, a certain amount of combustible gas needs to be continuously injected and combusted in an auxiliary mode to improve the flue gas temperature (more than 800 ℃) of the CONSTEEL electric furnace and the quantum electric furnace, so the steelmaking cost of the CONSTEEL electric furnace and the quantum electric furnace is increased to a certain extent.
3. The smoke purification treatment process of the CONSTEEL electric furnace and the quantum electric furnace loses a large amount of waste heat in the smoke of the electric furnace; in addition, a large amount of water is consumed; and causes a "plume" problem.
4. When the CONSTEEL electric furnace and the quantum electric furnace are in the oxygen blowing smelting peak, the high-temperature smoke is high in temperature, and the phenomenon that the scrap steel is softened and sticky due to the fact that the scrap steel preheating temperature is too high is often caused in the process of passing through the scrap steel continuous preheating device (or certain low-temperature alloy substances also exist in the scrap steel) and certain influence is caused on the stable operation of the scrap steel continuous preheating conveying device.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a dry method for treating flue gas of an electric furnace, which solves one or more problems of the prior art.
In order to achieve the purpose, the technical scheme of the invention is as follows:
an electric furnace flue gas dry processing method comprises the following steps:
1) flue gas mixed combustion settlement: starting an electric furnace body and a scrap steel continuous preheating mechanism to generate smoke, starting a fan of a dust removal device, extracting high-temperature smoke and low-temperature smoke from the electric furnace body and the scrap steel continuous preheating mechanism respectively, mixing the high-temperature smoke and the low-temperature smoke in a combustion settling cylinder, and enabling the temperature of the smoke in the combustion settling cylinder to be more than or equal to 800 ℃ through an aerobic auxiliary heating burner, and staying in the combustion settling cylinder for 2-3s, so that toxic substances such as dioxin/furan and the like contained in the smoke are effectively burned and decomposed at high temperature, and ash materials generated by burning are settled in a settling ash hopper;
2) quenching flue gas: the flue gas sent out from the combustion settling cylinder is sent into a plurality of quenching waste heat boilers, meanwhile, cooling water also enters the quenching waste heat boilers, and the flue gas and the cooling water exchange heat in the quenching waste heat boilers, so that the flue gas is rapidly cooled, the dioxin in the flue gas is prevented from being synthesized again, and meanwhile, the cooling water absorbs heat to heat up, and the waste heat in oxygen is recovered;
3) flue gas dust removal: the flue gas sent out from the quenching waste heat boiler enters a dust remover, particulate matters in the flue gas are filtered and intercepted through a cloth bag or a filter cylinder in the dust remover, the flue gas is purified, and the purified flue gas is discharged through a fan and a chimney;
4) ash removal operation: the ash is removed through the ash removing mechanism, so that the particles intercepted by the cloth bag or the filter cylinder are separated from the cloth bag or the filter cylinder and fall into the ash removing hopper.
As a further improvement of the above technical solution:
the electric furnace flue gas dry treatment method can be applied to treatment of flue gas generated by a CONSTEEL electric furnace or treatment of flue gas generated by a quantum electric furnace.
Before the electric furnace is operated for the first time or before the electric furnace ash removal is operated again, the operation of pre-spraying a fine powder layer is firstly carried out: starting a fan of the dust removal device, mixing air and fine powder, conveying the gas-solid mixed fine powder to a fine powder pre-spraying mechanism connected with the dust removal device, spraying the fine powder into a dust removal chamber of the dust removal device by the fine powder pre-spraying mechanism, pre-spraying the fine powder on the outer surfaces of cloth bags or filter cylinders in the dust removal device to enable fine powder layers with certain thicknesses to be reserved on the outer surfaces of the cloth bags or the filter cylinders, closing the fan of the dust removal device after the fine powder pre-spraying is finished, operating the electric furnace again, and continuously treating the flue gas of the electric furnace.
The fine powder contains 15-20% by mass of Ca (OH) 2 Fine powder and active carbon fine powder with the mass percent range of 80-85%; the grain size of the fine powder is less than 0.08-0.09 mm.
The fine powder can be sprayed into a flue gas pipeline connected with a flue gas inlet of the dust remover and is used for carrying out 'flow carrying type' adsorption treatment on dioxin in flue gas.
The fine powder is placed in the powder bin, a first fluidized drying mechanism is arranged at the lower end of the powder bin, the first fluidized drying mechanism can send high-temperature and high-pressure air into the powder bin, an ash hopper of the dust remover is connected with a second fluidized mechanism by the lower end, and the second fluidized drying mechanism can send the high-temperature and high-pressure air into the dust removing ash hopper and is respectively used for fluidized drying of fine powder and ash generated by dust removal, so that the fine powder and the ash are prevented from being condensed, deliquesced and hardened.
The pressure in the dust remover flue gas inlet and each dust removal chamber of the dust remover can be tested, and whether the thickness of the fine powder layer on the outer side of the cloth bag or the filter cylinder reaches the standard or not can be judged visually according to the pressure difference value between each dust removal chamber and the flue gas inlet.
A temperature sensor for detecting the temperature of the flue gas is arranged on a flue gas pipeline connected with a flue gas inlet of the dust remover, and high-temperature high-pressure air or low-temperature low-pressure air can be introduced into the flue gas pipeline to adjust the temperature of the flue gas.
The flue gas pipeline connected with the electric furnace body is connected with the air heat exchanger, heat exchange is carried out between high-temperature flue gas in the electric furnace body and air in the air heat exchanger, and the high-temperature flue gas is used as a heat source for heating the air, so that energy required by heating the air is saved.
The smoke pressure of the smoke inlet and the smoke outlet of the dust remover can be tested, and whether the dust removal operation is needed or not can be visually judged according to the pressure difference value between the smoke inlet and the smoke outlet.
Compared with the prior art, the invention has the following beneficial technical effects:
1) respectively extracting flue gas from the electric furnace body and the scrap steel continuous preheating mechanism, mixing the flue gas in the combustion settling cylinder to enable the temperature of the flue gas to be more than or equal to 800 ℃, and retaining the flue gas in the combustion settling cylinder for 2-3s to enable toxic substances such as dioxin/furan and the like contained in the flue gas to be effectively incinerated and decomposed at high temperature;
2) part of high-temperature flue gas in the electric furnace is pumped out, so that the temperature of the flue gas in the electric furnace can be reduced, and the problem that the scrap furnace burden in the scrap continuous preheating mechanism is sticky due to overhigh temperature of the flue gas can be effectively avoided;
3) before the electric furnace is put into operation or after the ash removal operation, a fine powder layer with certain thickness is sprayed outside a cloth bag or a filter cylinder in a filter dust collector, and the fine powder layer is made of Ca (OH) 2 The filter consists of fine powder and active carbon fine powder, can more thoroughly filter and adsorb toxic substances such as dioxin/furan and the like remained in smoke of the CONSTEEL electric furnace and the quantum electric furnace, and can effectively avoid the problem of bag pasting caused by condensation and dewing of filter materials of a filter dust collector;
4) the rapid cooling of the flue gas is realized by adopting a rapid cooling waste heat boiler, the dry rapid cooling of the flue gas is realized, the consumption of water is reduced to zero, the problem of smoke plume is avoided, the waste heat can be recovered, and the energy recovery is realized;
5) fine powder can be sprayed into a flue gas pipeline connected with a flue gas inlet of the dust remover, so that the dioxin in the flue gas is adsorbed and treated in a 'entrained flow mode';
6) a flue gas pipeline connected with a flue gas inlet of the dust remover is provided with a temperature sensor for detecting the temperature of the flue gas, and high-temperature high-pressure air or low-temperature low-pressure air can be introduced into the flue gas pipeline for adjusting the temperature of the flue gas, so that the problem that filter materials are condensed, condensed and pasted into bags is avoided, the temperature of the flue gas entering the dust remover is stable, the temperature change of the flue gas is prevented from being overlarge, and the service life of the dust remover is shortened;
7) high-temperature and high-pressure air is respectively introduced into the powder bin and the dust removal ash hopper through the first fluidized drying mechanism and the second fluidized drying mechanism, so that fine powder and ash can be fluidized and dried, and the fine powder and the ash are prevented from being condensed, deliquesced and hardened;
8) the flue gas pipeline connected with the electric furnace is connected with an air heat exchanger, heat exchange is carried out between high-temperature flue gas in the electric furnace and air in the air heat exchanger, and the high-temperature flue gas is used as a heat source for heating the air, so that energy required by heating the air is saved;
9) by detecting the pressure difference between the flue gas inlet and the flue gas outlet of the dust remover, whether the dust removal operation is required can be visually judged;
10) by detecting the pressure difference value between each dust removing chamber and the smoke inlet of the dust remover, the thickness of the fine powder layer outside the cloth bag or the filter cylinder in each dust removing chamber can be judged to reach the standard through a straight pipe.
Drawings
FIG. 1 shows a flow chart of a smelting process of a traditional CONSTEEL electric furnace and a quantum electric furnace.
Fig. 2 shows a flow chart of the electric furnace flue gas dry treatment method of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following detailed description of the present invention is provided with reference to the accompanying drawings and the detailed description. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are not to precise scale, and are provided for the purpose of facilitating and clearly illustrating embodiments of the present invention. To make the objects, features and advantages of the present invention more comprehensible, reference is made to the accompanying drawings. It should be understood that the structures, ratios, sizes, and the like shown in the drawings and described in the specification are only used for matching with the disclosure of the specification, so as to be understood and read by those skilled in the art, and are not used to limit the implementation of the present invention, so that the present invention has no technical significance, and any structural modification, ratio relationship change or size adjustment should fall within the scope of the present invention without affecting the efficacy and the achievable purpose of the present invention.
Example one
As shown in fig. 2, the electric furnace flue gas dry processing method of the embodiment includes the following steps:
1) pre-spraying fine powder layer operation: starting a fan of the dust removal device, mixing air and fine powder, conveying the gas-solid mixed fine powder to a fine powder pre-spraying mechanism connected with the dust remover, spraying the powder into a dust removal chamber of the dust remover by the fine powder pre-spraying mechanism, pre-spraying the fine powder on the outer surfaces of cloth bags or filter cylinders in the dust remover to ensure that fine powder layers with certain thicknesses are reserved on the outer surfaces of the cloth bags or the filter cylinders, closing the fan of the dust removal device after the fine powder pre-spraying is finished, operating the electric furnace again, and continuously treating the flue gas of the electric furnace;
2) flue gas mixed combustion settlement: starting an electric furnace body and a scrap steel continuous preheating mechanism to generate smoke, starting a fan of a dust removal device, extracting high-temperature smoke and low-temperature smoke from the electric furnace body and the scrap steel continuous preheating mechanism respectively, mixing the high-temperature smoke and the low-temperature smoke in a combustion settling cylinder, and enabling the temperature of the smoke in the combustion settling cylinder to be more than or equal to 800 ℃ through an aerobic auxiliary heating burner, and staying in the combustion settling cylinder for 2-3s, so that toxic substances such as dioxin/furan and the like contained in the smoke are effectively burned and decomposed at high temperature, and ash materials generated by burning are settled in a settling ash hopper;
3) quenching flue gas: the flue gas sent out from the combustion settling cylinder is sent into a plurality of quenching waste heat boilers, meanwhile, cooling water also enters the quenching waste heat boilers, the flue gas and the cooling water exchange heat in the quenching waste heat boilers (the high-temperature flue gas is quenched at the cooling speed of 300 ℃/s), the quick cooling of the flue gas is realized, the dioxin in the flue gas is prevented from being synthesized again, meanwhile, the cooling water absorbs heat to heat, and the waste heat in oxygen is recovered;
4) flue gas dust removal: the flue gas sent out from the quenching waste heat boiler enters a dust remover, particulate matters in the flue gas are filtered and intercepted through a cloth bag or a filter cylinder in the dust remover, the flue gas is purified, and the purified flue gas is discharged through a fan and a chimney;
5) ash removal operation: the dust is removed by a dust removing mechanism (such as a pulse blowing mechanism), so that the particles intercepted by the cloth bag or the filter cylinder are separated from the cloth bag or the filter cylinder and fall into a dust removing hopper.
The electric furnace flue gas dry treatment method of the embodiment can be applied to treatment of flue gas generated by a CONSTEEL electric furnace or a quantum electric furnace
Before the CONSTEEL electric furnace or the quantum electric furnace is put into operation for the first time or before the ash removal is finished and the secondary start is carried out, the step 1) is firstly carried out, so that a fine powder layer with a certain thickness is reserved on the outer surface of each cloth bag or filter cylinder, whether the thickness of the fine powder layer reaches the standard or not is judged visually according to the pressure difference of each dust removing chamber of the dust remover;
when the CONSTEEL electric furnace or the quantum electric furnace normally moves, only the step 2), the step 3) and the step 4) need to be carried out, the flue gas emission of the CONSTEEL electric furnace or the quantum electric furnace can be ensured to reach the standard through the flue gas treatment, and toxic substances such as dioxin/furan and the like contained in the flue gas are less than or equal to 0.1 ng-TEQ/m 3 ；
By detecting the pressure difference between the flue gas inlet and the flue gas outlet of the dust remover, whether the dust removal operation in the step 5) is required can be visually judged;
the fine powder contains 15-20% by mass of Ca (OH) 2 Fine powder and active carbon fine powder with the mass percent range of 80-85%; the particle size of the fine powder is less than 0.08-0.09 mm, residual toxic substances such as dioxin/furan and the like in the flue gas can be filtered and adsorbed more thoroughly through the fine powder layer, and the problem of bag pasting caused by condensation and dewing of filter materials of a dust remover can be prevented.
And the fine powder can be sprayed into a flue gas pipeline connected with a flue gas inlet of the dust remover and is used for carrying out 'flow carrying' adsorption treatment on dioxin in flue gas.
Set up on the flue gas pipeline of the flue gas access connection of dust remover and be used for detecting flue gas temperature sensor, and can let in high temperature high-pressure air or low temperature low pressure air in the flue gas pipeline and be used for adjusting the flue gas temperature, guarantee to get into the flue gas temperature stability in the dust remover, the dust remover operation is stable, dust remover long service life.
The fine powder is placed in the powder bin, the lower end of the powder bin is provided with a first fluidized drying mechanism, the first fluidized drying mechanism can send high-temperature and high-pressure air into the powder bin, the ash bucket of the dust remover is connected with a second fluidized mechanism by the lower end, and the second fluidized drying mechanism can send the high-temperature and high-pressure air into the dust removal ash bucket and is respectively used for fluidizing and drying fine powder and ash materials generated by dust removal, so that the fine powder and the ash materials are prevented from being condensed, deliquesced and hardened.
The flue gas pipeline connected with the electric furnace body is connected with the air heat exchanger, heat exchange is carried out between high-temperature flue gas in the electric furnace body and air in the air heat exchanger, and the high-temperature flue gas is used as a heat source for heating the air, so that energy required by heating the air is saved.
The ash materials in the sedimentation ash bucket and the dust removal ash bucket can be conveyed to an ash storehouse for collection through a pneumatic ash conveying mechanism.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the present invention, and these changes and modifications should fall within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. An electric furnace flue gas dry processing method comprises the following steps:
1) flue gas mixed combustion settlement: starting an electric furnace body and a scrap steel continuous preheating mechanism to generate smoke, starting a fan of a dust removal device, extracting high-temperature smoke and low-temperature smoke from the electric furnace body and the scrap steel continuous preheating mechanism respectively, mixing the high-temperature smoke and the low-temperature smoke in a combustion settling cylinder, and enabling the temperature of the smoke in the combustion settling cylinder to be more than or equal to 800 ℃ through an aerobic auxiliary heating burner, and staying in the combustion settling cylinder for 2-3s, so that toxic substances such as dioxin/furan and the like contained in the smoke are effectively burned and decomposed at high temperature, and ash materials generated by burning are settled in a settling ash hopper;
2) quenching flue gas: the flue gas sent out from the combustion settling cylinder is sent into a plurality of quenching waste heat boilers, meanwhile, cooling water also enters the quenching waste heat boilers, and the flue gas and the cooling water exchange heat in the quenching waste heat boilers, so that the flue gas is rapidly cooled, the dioxin in the flue gas is prevented from being synthesized again, and meanwhile, the cooling water absorbs heat to heat up, and the waste heat in oxygen is recovered;
3) flue gas dust removal: the flue gas sent out from the quenching waste heat boiler enters a dust remover, particulate matters in the flue gas are filtered and intercepted through a cloth bag or a filter cylinder in the dust remover, the flue gas is purified, and the purified flue gas is discharged through a fan and a chimney;
4) ash removal operation: the ash is removed through the ash removing mechanism, so that the particles intercepted by the cloth bag or the filter cylinder are separated from the cloth bag or the filter cylinder and fall into the ash removing hopper.
2. The electric furnace flue gas dry treatment method according to claim 1, characterized in that: the electric furnace flue gas dry treatment method can be applied to treatment of flue gas generated by a CONSTEEL electric furnace or treatment of flue gas generated by a quantum electric furnace.
3. The electric furnace flue gas dry treatment method according to claim 1, characterized in that: before the electric furnace is operated for the first time or before the electric furnace ash removal is operated again, the operation of pre-spraying a fine powder layer is firstly carried out: starting a fan of the dust removal device, mixing air and fine powder, conveying the gas-solid mixed fine powder to a fine powder pre-spraying mechanism connected with the dust remover, spraying the fine powder into a dust removal chamber of the dust remover by the fine powder pre-spraying mechanism, pre-spraying the fine powder on the outer surfaces of cloth bags or filter cartridges in the dust remover to ensure that fine powder layers with certain thicknesses are reserved on the outer surfaces of the cloth bags or the filter cartridges, closing the fan of the dust removal device after the fine powder pre-spraying is finished, operating the electric furnace again, and continuously treating the flue gas of the electric furnace.
4. The electric furnace flue gas dry treatment method according to claim 3, characterized in that: the fine powder contains 15-20% by mass of Ca (OH) 2 Fine powder and active carbon fine powder with the mass percent range of 80-85%; the grain size of the fine powder is less than 0.08-0.09 mm.
5. The electric furnace flue gas dry treatment method according to claim 3, characterized in that: the fine powder can be sprayed into a flue gas pipeline connected with a flue gas inlet of the dust remover and is used for carrying out 'flow carrying' adsorption treatment on dioxin in flue gas.
6. The electric furnace flue gas dry processing method according to claim 3, characterized in that: the fine powder is placed in the powder bin, a first fluidized drying mechanism is arranged at the lower end of the powder bin, the first fluidized drying mechanism can send high-temperature and high-pressure air into the powder bin, an ash hopper of the dust remover is connected with a second fluidized mechanism by the lower end, and the second fluidized drying mechanism can send the high-temperature and high-pressure air into the dust removing ash hopper and is respectively used for fluidized drying of fine powder and ash generated by dust removal, so that the fine powder and the ash are prevented from being condensed, deliquesced and hardened.
7. The electric furnace flue gas dry treatment method according to claim 3, characterized in that: the pressure in the dust remover flue gas inlet and each dust removal chamber of the dust remover can be tested, and whether the thickness of the fine powder layer on the outer side of the cloth bag or the filter cylinder reaches the standard or not can be judged visually according to the pressure difference value between each dust removal chamber and the flue gas inlet.
8. The electric furnace flue gas dry treatment method according to claim 1, characterized in that: a temperature sensor for detecting the temperature of the flue gas is arranged on a flue gas pipeline connected with a flue gas inlet of the dust remover, and high-temperature high-pressure air or low-temperature low-pressure air can be introduced into the flue gas pipeline to adjust the temperature of the flue gas.
9. The electric furnace flue gas dry treatment method according to claim 6 or 7, characterized in that: the flue gas pipeline connected with the electric furnace body is connected with the air heat exchanger, heat exchange is carried out between high-temperature flue gas in the electric furnace body and air in the air heat exchanger, and the high-temperature flue gas is used as a heat source for heating the air, so that energy required by heating the air is saved.
10. The electric furnace flue gas dry treatment method according to claim 1, characterized in that: the smoke pressure of the smoke inlet and the smoke outlet of the dust remover can be tested, and whether the dust removal operation is needed or not can be visually judged according to the pressure difference value between the smoke inlet and the smoke outlet.
CN202210473648.5A 2022-04-29 2022-04-29 Electric furnace flue gas dry processing method Pending CN114963783A (en)

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