CN108692579B - Synergistic treatment process for sinter waste heat and sintering flue gas pollutants - Google Patents
Synergistic treatment process for sinter waste heat and sintering flue gas pollutants Download PDFInfo
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- CN108692579B CN108692579B CN201810355829.1A CN201810355829A CN108692579B CN 108692579 B CN108692579 B CN 108692579B CN 201810355829 A CN201810355829 A CN 201810355829A CN 108692579 B CN108692579 B CN 108692579B
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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
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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
- F27D17/008—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases cleaning gases
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Abstract
The invention relates to a synergistic treatment process of sintering ore waste heat and sintering flue gas pollutants, which comprises the step of enabling sintering flue gas generated by metallurgical sintering to pass through a dust removal partCarrying out heat exchange treatment on the particles after the particles are removed and sintered ores generated by metallurgical sintering, and oxidizing and removing at least part of CO in sintering flue gas in the heat exchange treatment; and the sintering flue gas is subjected to CO removal treatment, wherein at least part of CO in the flue gas is oxidized and removed in the CO removal treatment. According to the arrangement condition of the prior sintering machine and the desulfurization system, the sintering flue gas can be subjected to SO removal firstly2Or finally removing SO2The process of (1). The CO-processing technology solves the problems of CO removal and utilization, and realizes CO-processing of sinter waste heat and sintering flue gas pollutants.
Description
Technical Field
The invention relates to waste utilization in the metallurgical industry, in particular to the field of waste heat utilization and pollutant treatment.
Background
Under the background of global warming and ecological environment deterioration at present, the energy conservation and emission reduction of sintering have important significance on the sustainable development of the steel industry. According to statistics, the energy consumption of the sintering process accounts for about more than 15% of the energy consumption of the whole steel industry, and the pollutant emission accounts for about 40% of the energy consumption of the whole steel industry. In recent years, with the increasing concern of the nation on energy conservation and emission reduction, the utilization of the waste heat of sintering ore and the smoke pollutants such as dust and SO of a sintering machine head appear in succession in the sintering field2With the improvement of the national environmental protection standard, NO in the sintering flue gas appearsxThe processing technique of (1). But the technologies of sintering waste heat utilization and smoke pollutant treatment are developed respectively, although the technologies become mature day by day, the results are not satisfactory. The main reason is that the utilization rate of the sintering waste heat is low at present, and a large amount of energy consumption is needed in the process of treating the smoke pollutants, so that the operation cost of a sintering system is continuously increased.
During the sintering production process, approximately 15% of the energy is discharged as sensible heat of the sintering flue gas and approximately 35% of the energy is discharged as sensible heat of the sinter. The sensible heat of the two forms accounts for more than 50% of the total energy consumed in the sintering process. In addition, in the sintering process, about 1/4 of C is converted into CO and discharged along with sintering flue gas, which not only causes pollution to the environment, but also causes huge waste of energy. It was estimated that the energy lost by incomplete combustion of C was about 15% of the total energy of sintering. The three parts of energy account for about 65% of total sintering energy, and are all discharged into the atmosphere in various forms at present, which not only causes huge waste of resources, but also causes environmental pollution and heat effect of industrial enterprises. Of the three parts of energy, only part of sensible heat of the sintered ore can be recycled at present, but the recovery rate is generally less than 30%, and the consumed electric energy accounts for about 20% of the total power generation. That is, the current sintering waste heat recovery technology is not sufficient for recovering sintering energy by 10%.
With the increasing environmental protection situation of China, the development of the treatment process of sintering flue gas pollutants is rapid, and at present, particles and SO in the sintering flue gas are2Has been substantially mature in the removal process of NOxThe removal process of (a) is rapidly developing, and three directions of an activated carbon process, an ozone denitration process and an SCR denitration process have been generally formed. At present, although three denitration processes can meet the national ultra-low emission index requirements, the three denitration processes have some disadvantages, which are mainly expressed as follows: 1. the activated carbon process comprises the following steps: 1) the one-time investment cost and the later operation and maintenance cost are high; 2) the coal resource amount for the activated carbon is limited, and the situation that no activated carbon is available is faced in the future. 2. And (3) ozone denitration: 1) the electricity consumption cost is high, and the ozone conversion rate is low; 2) the desulfurization cloth bag has strong oxidation effect, and the service life of the dust removal cloth bag is influenced; 3) ozone, as one of the atmospheric pollutants, causes new atmospheric pollution. 3. And (3) SCR denitration process: 1) the low-temperature denitration efficiency is low; 2) a large amount of energy is consumed to heat the flue gas. The above processes have been realized for SO in flue gas2、NOxAnd the removal of the particulate matters, but the removal of CO which is one of the pollutants in the flue gas is ineffective. Through monitoring, the concentration of CO in the sintering flue gas is far higher than that of SO2、NOxAnd the like. By monitoring, the main pollutant data in the sintering flue gas are as follows: SO (SO)2600-2000mg/m3、NOx200-400mg/m3、CO 8000-25000mg/m3。
The ring cooling machine used for treating sintering flue gas and sintering ores in the prior art has the problems of poor sealing performance, great difference between the actually utilized flue gas amount of the ring cooling machine and the sintering flue gas amount, low flue gas temperature after heat exchange and the like. The flue gas after wet desulphurization can not return to the ring cooling machine for heat exchange, and the flue gas after wet desulphurization contains a large amount of acid gas, so that the flue gas has a strong corrosion effect on subsequent equipment, particularly the ring cooling machine, and particularly the corrosion on rotating parts such as wheels and the like of the ring cooling machine. The processes do not well solve the problem that denitration and CO removal cannot be normally carried out due to the conditions of starting and stopping the sintering machine, short-time stopping of the sintering machine and the like.
Disclosure of Invention
The invention provides a waste heat and pollutant cooperative treatment process for solving the problems in the prior art.
According to one aspect of the invention, the invention provides a synergistic treatment process of sintering ore waste heat and sintering flue gas pollutants, which comprises the steps of removing particles from sintering flue gas generated by metallurgical sintering through dust removal treatment and removing SO through desulfurization treatment2Then, carrying out heat exchange treatment with sintered ores generated by metallurgical sintering, and oxidizing and removing at least part of CO in sintering flue gas in the heat exchange treatment; carrying out CO removal treatment on the sintering flue gas subjected to heat exchange treatment, wherein at least part of CO in the flue gas is oxidized and removed in the CO removal treatment; then removing NO from the sintering flue gas subjected to CO removal treatment through denitration treatmentxCarrying out heat exchange treatment on the sintering flue gas after denitration treatment; and the sintered ore is subjected to heat exchange treatment to obtain a sintered ore finished product and is conveyed away.
Further, the CO removal treatment is performed in a CO removal furnace, which is a device that increases the temperature of CO to a reaction temperature by using heat generated by oxidation of an auxiliary fuel, thereby generating oxidation.
Further, the treatment process comprises the steps that sintering flue gas generated by the sintering machine enters a dust removal system to be subjected to dust removal treatment to remove particles; the rear part of the dust removal system is connected with a main exhaust fan and is used for sending sintering flue gas into a desulfurization system for desulfurization treatment and removal of SO2(ii) a The sintering flue gas after desulfurization enters a closed furnace, sintering ores generated by a sintering machine are also sent into the closed furnace, the sintering flue gas in the closed furnace and the sintering ores are subjected to heat exchange treatment, and at least part of CO in the sintering flue gas is removed by oxidation in the heat exchange treatment; the sintering flue gas conveyed out of the closed furnace enters a CO removal furnace for CO removal treatment, and at least part of CO in the flue gas is oxidized and removed in the CO removal treatment; then the sintering flue gas after CO removal treatment enters a denitration system for denitration treatment and NO removalxDenitration ofThe treated sintering flue gas enters a heat exchanger for heat exchange treatment, and the sintering flue gas after heat exchange treatment is discharged; and the sintered ore is subjected to heat exchange treatment to obtain a sintered ore finished product and is conveyed away from the closed furnace.
Further, the temperature of the sintering flue gas after desulfurization treatment is 75-95 ℃; the temperature of the sintered ore fed into the closed furnace is more than 750 ℃; the temperature of the sintering flue gas after CO removal treatment is more than 400 ℃; the temperature of the sintering flue gas after heat exchange treatment by the heat exchanger is below 130 ℃.
Further, the co-processing technology further comprises the step of heating the sintering flue gas subjected to heat exchange processing.
Further, the dust removal system comprises an electrostatic dust removal device.
Further, the desulfurization system adopts a dry or semi-dry desulfurization process.
Further, the denitration system may use a Selective Catalytic Reduction (SCR) denitration process.
According to one aspect of the invention, the invention provides a synergistic treatment process of sintering ore waste heat and sintering flue gas pollutants, which comprises the steps of carrying out heat exchange treatment on a part of sintering flue gas generated by metallurgical sintering and sintering ores generated by the metallurgical sintering after removing particles through dust removal treatment, and oxidizing and removing at least part of CO in the sintering flue gas in the heat exchange treatment; one part of sintering flue gas generated by metallurgical sintering is subjected to dust removal treatment to remove particles and then is converged with the sintering flue gas subjected to heat exchange treatment, the converged sintering flue gas is subjected to CO removal treatment, and at least part of CO in the sintering flue gas is oxidized and removed in the CO removal treatment; then removing the CO treated sintering flue gas for heat exchange treatment, and removing NO by carrying out denitration treatment on the heat exchange treated sintering flue gasxCarrying out secondary heat exchange treatment on the sintering flue gas after denitration treatment, and then carrying out desulfurization treatment on the flue gas after secondary heat exchange treatment to remove SO2。
Further, the CO removal treatment is performed in a CO removal furnace, which is a device that increases the temperature of CO to a reaction temperature by using heat generated by oxidation of an auxiliary fuel, thereby generating oxidation.
Further, the treatment process comprises the steps that a part of sintering flue gas generated by the sintering machine enters a dust removal system I for dust removal treatment and particulate matter removal, the rear part of the dust removal system I is connected with a main exhaust fan, the main exhaust fan sends the sintering flue gas into a closed furnace, sintered ores generated by the sintering machine are also sent into the closed furnace, the sintering flue gas and the sintered ores in the closed furnace are subjected to heat exchange treatment, and at least part of CO in the sintering flue gas is oxidized and removed in the heat exchange treatment; one part of sintering flue gas generated by metallurgical sintering is subjected to dust removal treatment by a dust removal system II to remove particles, the dust removal system II is connected with a newly added fan, and the sintering flue gas conveyed by the newly added fan is converged with the sintering flue gas conveyed by the closed furnace; the converged sintering flue gas enters a CO removal furnace for CO removal treatment, and at least part of CO in the sintering flue gas is oxidized and removed in the CO removal treatment; then the sintering flue gas after CO removal treatment enters a heat exchanger for heat exchange treatment, and the sintering flue gas after heat exchange treatment enters a denitration system for denitration treatment and NO removalxThe sintering flue gas after denitration treatment enters a secondary heat exchanger for secondary heat exchange treatment, and then enters a desulfurization system for desulfurization treatment and SO removal2(ii) a And the sintered ore is subjected to heat exchange treatment to obtain a sintered ore finished product and is conveyed away from the closed furnace.
Further, the co-processing technology further comprises the step of heating the converged sintering flue gas.
The invention has the advantages that:
1) the recovery rate of sensible heat of the sintering ore is greatly improved, and the problem that the sintering flue gas is low in temperature and cannot be recycled is solved; the countercurrent heat exchange process of the sintering flue gas matched with the vertical closed cooling furnace is adopted, so that the problems of poor sealing effect, low heat exchange rate and unmatched cooling flue gas quantity and sintering flue gas quantity of the circular cooler are solved;
2) a CO removal furnace is added, so that the problems that CO in the sintering flue gas can not be removed as a pollutant and can not be recycled as an energy source are solved, and the CO in the sintering flue gas is recycled; solves various sinteringCO and NO under working condition, especially under working condition of starting and stopping of sintering machinex、SO2And the problem of dioxin removal;
3) removal of NO by SCR denitration processxThe flue gas is not specially heated, so that the energy consumption is reduced, and compared with the existing denitration process, the process can remove NOxMeanwhile, economic benefits are generated;
4) can realize the synchronous treatment of partial heavy metal and dioxin in the flue gas and realize the CO and NO in the sintering flue gasx、SO2Synchronously removing dioxin;
5) the recovery rate of the sintering residual energy reaches more than 40 percent, and the economic benefit is greatly improved.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a process flow diagram of the present invention for the co-treatment of waste heat and pollutants;
FIG. 2 is a temperature rise diagram of the co-treatment process of the present invention;
FIG. 3 is a flow chart of an improved process for the co-treatment of waste heat and pollutants in accordance with the present invention;
FIG. 4 is a temperature rise diagram of the improved process of the co-treatment of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The invention relates to a method for producing sintered ore by waste heatThe co-processing technology of sintering flue gas pollutants comprises the steps of removing particles from sintering flue gas generated by metallurgical sintering through dust removal treatment and removing SO through desulfurization treatment2Then, carrying out heat exchange treatment with sintered ores generated by metallurgical sintering, and oxidizing and removing at least part of CO in sintering flue gas in the heat exchange treatment; carrying out CO removal treatment on the sintering flue gas subjected to heat exchange treatment, wherein at least part of CO in the flue gas is oxidized and removed in the CO removal treatment; then removing NO from the sintering flue gas subjected to CO removal treatment through denitration treatmentxCarrying out heat exchange treatment on the sintering flue gas after denitration treatment; and the sintered ore is subjected to heat exchange treatment to obtain a sintered ore finished product and is conveyed away.
According to one embodiment of the invention, as shown in fig. 1, in the coordinated treatment process of the sintering ore waste heat and the sintering flue gas pollutants, sintering flue gas generated by a sintering machine enters a dust removal system to remove dust and particulate matters; the rear part of the dust removal system is connected with a main exhaust fan and is used for sending sintering flue gas into a desulfurization system for desulfurization treatment and removal of SO2(ii) a The sintering flue gas after desulfurization enters a closed furnace, sintering ores generated by a sintering machine are also sent into the closed furnace, the sintering flue gas in the closed furnace and the sintering ores are subjected to heat exchange treatment, and at least part of CO in the sintering flue gas is removed by oxidation in the heat exchange treatment; the sintering flue gas conveyed out of the closed furnace enters a CO removal furnace for CO removal treatment, and at least part of CO in the flue gas is oxidized and removed in the CO removal treatment; then the sintering flue gas after CO removal treatment enters a denitration system for denitration treatment and NO removalxThe sintering flue gas after the denitration treatment enters a heat exchanger for heat exchange treatment, for example, high-temperature and high-pressure steam generated after heat exchange by the heat exchanger is used for pushing a steam turbine to generate electricity for a power generation system, and the sintering flue gas after the heat exchange treatment is discharged, for example, from a chimney; and the sintered ore is subjected to heat exchange treatment to obtain a sintered ore finished product, and the sintered ore finished product is conveyed away from the closed furnace, such as by using a finished product belt. Because most sintering machines at present are provided with a desulfurization system, and are basically arranged at the position behind or on one side of a main chimney of the sintering machine, the position is far away from the position of the current circular cooler. Consider utilizing the presentThe desulfurization process of (1) can be modified on the basis of the above-mentioned embodiment by using the co-treatment process.
According to another embodiment of the invention, the CO-processing technology of the sintering ore waste heat and the sintering flue gas pollutants further comprises a step of heating the sintering flue gas subjected to heat exchange treatment, for example, at least one set of flue gas heating furnace is used for heating the flue gas, so that the denitration and CO removal capabilities can be ensured under the conditions of starting and stopping the sintering machine, large fluctuation of the sintering machine and the like. Meanwhile, the flue gas heated by the heating furnace can be recovered by the heat exchanger.
In the above embodiment, the dust removal system may select an electrostatic precipitator (ESP) device, which is a device that separates dust from flue gas by using electrostatic force. When the sintering flue gas is extracted from the sintering machine through the main exhaust fan, the sintering flue gas firstly passes through ESP equipment, and most of dust in the flue gas can be removed.
In the above embodiment, the desulfurization system may adopt a semi-dry or dry desulfurization process, such as a spray-drying desulfurization process, a flue gas circulating fluidized bed desulfurization process, a furnace calcium-spraying tail-humidification desulfurization process, and the like. The sulfide in the flue gas can be effectively removed before the flue gas is introduced into the closed furnace. Wherein the temperature of the flue gas after desulfurization is 75-95 ℃.
In the above embodiment, the closed furnace may be a vertical closed cooling furnace, and the vertical closed cooling furnace may be used in combination with a countercurrent heat exchange process of the sintering flue gas, so that the flue gas discharged from the main sintering exhaust fan is introduced into the closed furnace to perform a heat exchange process with the sintered ore, and the sintered ore is cooled. The problems that the sealing performance of the annular cooling furnace is poor, the difference between the actually utilized flue gas quantity and the sintering flue gas quantity is large, the temperature of the flue gas after heat exchange is low and the like are solved. And because the temperature of the sintered ore entering the closed furnace is more than 750 ℃, the temperature of part of the sintered ore can reach more than 1000 ℃, when the sintering flue gas passes through the sintered ore with the temperature of more than 750 ℃, CO can be reoxidized, the purpose of removing CO partially is achieved, and the energy generated by CO oxidation is released into the flue gas. CO oxidation refers to CO with O2The reaction is carried out. By heat of flue gases with sinterExchange and CO oxidation, so that the temperature of the sintering flue gas rises. And because the decomposition temperature of the dioxin is 500 ℃, the dioxin can be completely decomposed within 12s at 800 ℃, so that the dioxin in the sintering flue gas can be decomposed when passing through a hot sintering ore in a closed furnace. And when the flue gas meets the sintered ore, the flue gas can partially adsorb heavy metals due to the porous structure of the sintered ore. And a countercurrent heat exchange process of sintering flue gas matched with a vertical closed cooling furnace is adopted, so that the problems of poor sealing effect, low heat exchange rate and unmatched cooling flue gas quantity and sintering flue gas quantity of the circular cooler are solved.
In the above embodiment, the CO removal furnace is a device that generates oxidation by raising the temperature of CO to a reaction temperature using heat generated by oxidation of an auxiliary fuel (such as blast furnace gas, coke oven gas, or natural gas). The method is mainly suitable for removing CO when the concentration of CO in the flue gas is lower than the explosion limit. The explosion limit of CO in air is 12.5-74.2%, and the CO concentration in sintering flue gas is about 1-2%, so that the method is completely suitable for the operation condition of a CO removing furnace. Wherein CO oxidation refers to CO and O2The reaction is carried out. The flue gas from the closed furnace passes through a CO removing furnace, so that the CO in the flue gas is completely oxidized into CO2To realize the removal of CO and convert CO into CO2The heat generated is released into the flue gas. Meanwhile, the heat generated by the oxidation of the auxiliary fuel is also released into the flue gas, and the temperature of the flue gas rises to above 400 ℃. Therefore, through the combined action of the closed furnace and the CO removal furnace, the CO content in the flue gas is greatly reduced, the pollution is reduced, and the CO is effectively utilized as heat generated by oxidation. The temperature in the removing furnace is about 700-1000 ℃, and dioxin in the sintering flue gas is also decomposed when passing through the CO removing furnace. In addition, when special working conditions such as short-time fluctuation or startup and shutdown occur in sintering, the temperature of the flue gas is low after the flue gas passes through the cooling furnace or the CO concentration cannot meet the emission requirement, and the flue gas is introduced into the CO removing furnace, so that the effects of supplementing the temperature of the flue gas and reducing the CO concentration can be achieved.
In the above embodiments, the denitration system may use a Selective Catalytic Reduction (SCR) denitration process using a denitration reducing agent (liquid ammonia, ammonia water)Urea, etc.) under the action of catalyst to selectively remove NO from fumex(mainly NO, NO)2) Reduction to nitrogen (N)2) And water (H)2O) to thereby achieve the removal of NOxThe purpose of (1). When the temperature of the sintering flue gas rises to about 400 ℃, the NO in the sintering flue gas is subjected to the SCR denitration processxThe denitration efficiency of the process can reach 80-90 percent. And NO is removed by SCR denitration technologyxThe flue gas is not specially heated, so that the energy consumption is reduced. After SCR process, NOxWill be from 300mg/m3Reduced to 50mg/m3The following.
For the above embodiment, the final flue gas enters the heat exchanger of the power generation system for heat exchange, and the high-temperature and high-pressure steam generated after heat exchange by the heat exchanger is used for driving the steam turbine to generate power. The temperature of the flue gas after heat exchange of the heat exchanger is reduced to below 130 ℃.
According to another embodiment of the invention, as shown in fig. 2, the temperature of the flue gas after desulfurization is 85 ℃, the temperature after heat exchange in the closed furnace is 273 ℃, and the temperature after passing through the CO removal furnace is 436 ℃. Through theoretical calculation, the utilization rate of the process on the sintering residual energy is 38.5%, and the recovery rate of the existing annular cooling waste heat recovery on the sintering residual energy is less than 10%. The problem of heat loss caused by heating the flue gas in the prior sintering flue gas SCR denitration process is also solved, and the energy consumption of the coal gas required by the prior SCR heating accounts for more than 5 percent of the total sintering energy consumption.
According to the other coordinated treatment process of the waste heat of the sintered ore and the pollutants in the sintered flue gas, after the particles in the sintered flue gas generated by metallurgical sintering are removed through dust removal treatment, heat exchange treatment is carried out on the sintered flue gas and the sintered ore generated by metallurgical sintering, and at least part of CO in the sintered flue gas is removed through oxidation in the heat exchange treatment; one part of sintering flue gas generated by metallurgical sintering is subjected to dust removal treatment to remove particles and then is converged with the sintering flue gas subjected to heat exchange treatment, the converged sintering flue gas is subjected to CO removal treatment, and at least part of CO in the sintering flue gas is oxidized and removed in the CO removal treatment; then removing CO from the sintering flue gas for heat exchange treatment, and performing denitration treatment on the sintering flue gas subjected to heat exchange treatment for removing CONOxCarrying out secondary heat exchange treatment on the sintering flue gas after denitration treatment, and then carrying out desulfurization treatment on the flue gas after secondary heat exchange treatment to remove SO2。
As shown in fig. 3, a part of the sintering flue gas generated by the sintering machine enters a dust removal system I for dust removal treatment to remove particulate matters, the rear part of the dust removal system I is connected with a main exhaust fan, the main exhaust fan sends the sintering flue gas into a sealed furnace, the sintered ore generated by the sintering machine is also sent into the sealed furnace, the sintering flue gas and the sintered ore in the sealed furnace are subjected to heat exchange treatment, and at least part of CO in the sintering flue gas is oxidized and removed in the heat exchange treatment; one part of sintering flue gas generated by metallurgical sintering is subjected to dust removal treatment by a dust removal system II to remove particles, the dust removal system II is connected with a newly added fan, and the sintering flue gas conveyed by the newly added fan is converged with the sintering flue gas conveyed by the closed furnace; the converged sintering flue gas enters a CO removal furnace for CO removal treatment, and at least part of CO in the sintering flue gas is oxidized and removed in the CO removal treatment; then the sintering flue gas after CO removal treatment enters a heat exchanger for heat exchange treatment, and the sintering flue gas after heat exchange treatment enters a denitration system for denitration treatment and NO removalxThe sintering flue gas after denitration treatment enters a secondary heat exchanger for secondary heat exchange treatment, and then enters a desulfurization system for desulfurization treatment and SO removal2(ii) a And the sintered ore is subjected to heat exchange treatment to obtain a sintered ore finished product, and the sintered ore finished product is conveyed away from the closed furnace, such as by using a finished product belt. And the high-temperature and high-pressure steam generated after the heat exchange treatment and the secondary heat exchange treatment is used for driving a steam turbine to generate electricity for a power generation system.
The dust removal system, the desulfurization system, the closed furnace, the CO removal furnace, and the denitration system according to this embodiment are as described in the above-described embodiments. And considering that the flue gas temperature is higher after the sintering flue gas passes through the closed furnace and the CO removal furnace and is not suitable for the optimal reaction temperature of the SCR denitration process, a set of heat exchanger is added in front of the SCR denitration device, so that the flue gas is controlled at the optimal temperature of the SCR denitration process. For example, the temperature of the flue gas will rise to above 450 ℃ after passing through the CO removal furnace, and the temperature of the flue gas will drop to the proper temperature of the SCR after passing through the heat exchanger(300-420 ℃), thereby greatly improving the denitration effect of the SCR denitration technology and obviously reducing the emission of pollutants in the flue gas. And NO is removed by SCR denitration technologyxThe flue gas is not specially heated, so that the energy consumption is reduced. After SCR process, NOxWill be from 300mg/m3Reduced to 50mg/m3The following. The flue gas after the SCR denitration process enters a secondary heat exchanger for secondary heat exchange treatment, the high-temperature and high-pressure steam after the heat exchange of the secondary heat exchanger is used for driving a steam turbine to generate electricity, and the temperature of the flue gas after the heat exchange is reduced to about 130 ℃, SO that the SCR denitration process is just suitable for various current desulfurization processes to remove SO in the flue gas2And particles realize ultralow emission of flue gas.
According to one of the modified embodiments, if the sintering machine does not have a desulfurization system at present or the desulfurization system needs to be synchronously modified, the process flow can be adopted. A set of air extraction system is additionally arranged at the tail of the sintering machine, smoke of the last six air boxes (generally 44 air boxes of the sintering machine) of the sintering machine system is extracted through the newly-added air extraction system, the rest air boxes are still extracted by the original main exhaust fan, and turning plates are arranged at the lower parts of the last six air boxes, so that automatic switching between two flues can be realized. Through the scheme, as shown in fig. 4, the flue gas treatment capacity of the newly added flue gas treatment system is 20% of the total flue gas quantity, the flue gas temperature is about 350 ℃, the flue gas treatment capacity of the main exhaust fan is 80%, and the original main exhaust flue gas temperature is about 85 ℃. Then the two streams of flue gas were combined and passed through a CO removal furnace at a temperature of 489 ℃. Through theoretical calculation, the utilization rate of the process on the sintering residual energy is 43%, and the recovery rate of the existing annular cooling waste heat recovery on the sintering residual energy is less than 10%. The process also solves the problem of heat loss caused by heating the flue gas in the prior sintering flue gas SCR denitration process, and the energy consumption of the coal gas required by SCR heating accounts for more than 5 percent of the total sintering energy consumption. Comprehensive calculation shows that the utilization of the sintering residual energy can be improved to 43 percent from the original 10 percent compared with the prior art, the improvement range is more than 4 times of the prior art, and the power generation amount of the sintering residual energy is improved to 60 degrees/t from the prior 15 degrees/t ore.
According to another embodiment of the invention, the CO-processing technology of the sintering ore waste heat and the sintering flue gas pollutants further comprises heating the merged sintering flue gas, for example, at least one set of flue gas heating furnace is used for heating the flue gas, so that the denitration and CO removal capabilities can be ensured under the conditions of starting and stopping the sintering machine, large fluctuation of the sintering machine and the like. Meanwhile, the flue gas heated by the heating furnace can be recovered by the heat exchanger.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (6)
1. A co-processing technology of sinter waste heat and sintering flue gas pollutants is characterized in that: the treatment process comprises the steps of removing particles from sintering flue gas generated by metallurgical sintering through dust removal treatment and removing SO through desulfurization treatment2Then, carrying out heat exchange treatment with sintered ores generated by metallurgical sintering, and oxidizing and removing at least part of CO in sintering flue gas in the heat exchange treatment; carrying out CO removal treatment on the sintering flue gas subjected to heat exchange treatment, wherein at least part of CO in the flue gas is oxidized and removed in the CO removal treatment; then removing NO from the sintering flue gas subjected to CO removal treatment through denitration treatmentxCarrying out heat exchange treatment on the sintering flue gas after denitration treatment; the sintered ore is subjected to heat exchange treatment to obtain a sintered ore finished product and is conveyed away;
wherein the CO removal treatment is carried out in a CO removal furnace, and the CO removal furnace is equipment for raising the temperature of CO to a reaction temperature by using heat generated by oxidation of auxiliary fuel so as to generate oxidation; the temperature in the CO removing furnace is 700-1000 ℃; the temperature of the sintering flue gas after CO removal treatment is more than 400 ℃; the co-processing technology also comprises the step of heating the sintering flue gas subjected to heat exchange processing.
2. According to claimThe synergic treatment process of the sinter waste heat and the sintering flue gas pollutants as claimed in claim 1 is characterized in that: the treatment process comprises the steps that sintering flue gas generated by the sintering machine enters a dust removal system to be subjected to dust removal treatment to remove particles; the rear part of the dust removal system is connected with a main exhaust fan and is used for sending sintering flue gas into a desulfurization system for desulfurization treatment and removal of SO2(ii) a The sintering flue gas after desulfurization enters a closed furnace, sintering ores generated by a sintering machine are also sent into the closed furnace, the sintering flue gas in the closed furnace and the sintering ores are subjected to heat exchange treatment, and at least part of CO in the sintering flue gas is removed by oxidation in the heat exchange treatment; the sintering flue gas conveyed out of the closed furnace enters a CO removal furnace for CO removal treatment, and at least part of CO in the flue gas is oxidized and removed in the CO removal treatment; then the sintering flue gas after CO removal treatment enters a denitration system for denitration treatment and NO removalxThe sintering flue gas after denitration treatment enters a heat exchanger for heat exchange treatment, and the sintering flue gas after heat exchange treatment is discharged; and the sintered ore is subjected to heat exchange treatment to obtain a sintered ore finished product and is conveyed away from the closed furnace.
3. The process of claim 2, wherein the co-treatment of the sinter ore waste heat and the sintering flue gas pollutants comprises: the dust removal system comprises an electrostatic dust removal device; the desulfurization system adopts a dry or semi-dry desulfurization process; the denitration system uses a selective catalytic reduction denitration process.
4. The process of claim 2, wherein the co-treatment of the sinter ore waste heat and the sintering flue gas pollutants comprises: the temperature of the sintering flue gas after desulfurization treatment is 75-95 ℃; the temperature of the sintered ore fed into the closed furnace is more than 750 ℃; the temperature of the sintering flue gas after heat exchange treatment by the heat exchanger is below 130 ℃.
5. A co-processing technology of sinter waste heat and sintering flue gas pollutants is characterized in that: the treatment process comprises the steps of removing dust and particulate matters from part of sintering flue gas generated by metallurgical sinteringCarrying out heat exchange treatment with sintered ores generated by metallurgical sintering, and oxidizing and removing at least part of CO in sintering flue gas in the heat exchange treatment; one part of sintering flue gas generated by metallurgical sintering is subjected to dust removal treatment to remove particles and then is converged with the sintering flue gas subjected to heat exchange treatment, the converged sintering flue gas is subjected to CO removal treatment, and at least part of CO in the sintering flue gas is oxidized and removed in the CO removal treatment; then removing the CO treated sintering flue gas for heat exchange treatment, and removing NO by carrying out denitration treatment on the heat exchange treated sintering flue gasxCarrying out secondary heat exchange treatment on the sintering flue gas after denitration treatment, and then carrying out desulfurization treatment on the flue gas after secondary heat exchange treatment to remove SO2；
Wherein the CO removal treatment is carried out in a CO removal furnace, and the CO removal furnace is equipment for raising the temperature of CO to a reaction temperature by using heat generated by oxidation of auxiliary fuel so as to generate oxidation; the temperature in the CO removing furnace is 700-1000 ℃; the temperature of the flue gas is raised to more than 450 ℃ after the flue gas passes through the CO removing furnace; the co-processing technology also comprises the step of heating the converged sintering flue gas.
6. The process of claim 5, wherein the co-treatment process of the sinter ore waste heat and the sintering flue gas pollutants comprises the following steps: the treatment process comprises the following steps that a part of sintering flue gas generated by the sintering machine enters a dust removal system I for dust removal treatment and particulate matter removal, the rear part of the dust removal system I is connected with a main exhaust fan, the main exhaust fan sends the sintering flue gas into a sealed furnace, sintered ores generated by the sintering machine are also sent into the sealed furnace, the sintering flue gas and the sintered ores in the sealed furnace are subjected to heat exchange treatment, and at least part of CO in the sintering flue gas is removed by oxidation in the heat exchange treatment; one part of sintering flue gas generated by metallurgical sintering is subjected to dust removal treatment by a dust removal system II to remove particles, the dust removal system II is connected with a newly added fan, and the sintering flue gas conveyed by the newly added fan is converged with the sintering flue gas conveyed by the closed furnace; the converged sintering flue gas enters a CO removal furnace for CO removal treatment, and at least part of CO in the sintering flue gas is oxidized and removed in the CO removal treatment; then removing CO treated combustionThe sintering flue gas after heat exchange treatment enters a denitration system for denitration treatment and NO removalxThe sintering flue gas after denitration treatment enters a secondary heat exchanger for secondary heat exchange treatment, and then enters a desulfurization system for desulfurization treatment and SO removal2(ii) a And the sintered ore is subjected to heat exchange treatment to obtain a sintered ore finished product and is conveyed away from the closed furnace.
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| CN112944923A (en) * | 2021-02-25 | 2021-06-11 | 彭思尧 | Low-cost co-processing ultra-clean emission process and system for sintering flue gas of steel mill |
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| CN102997697B (en) * | 2012-12-12 | 2014-08-27 | 武汉钢铁(集团)公司 | Sinter waste-heat utilization process based on purification of sintering flue gas |
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