CN112044268A - Method and system for utilizing heat energy in flue gas treatment - Google Patents

Method and system for utilizing heat energy in flue gas treatment Download PDF

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CN112044268A
CN112044268A CN201910484052.3A CN201910484052A CN112044268A CN 112044268 A CN112044268 A CN 112044268A CN 201910484052 A CN201910484052 A CN 201910484052A CN 112044268 A CN112044268 A CN 112044268A
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flue gas
conveying pipeline
heat exchanger
gas
temperature
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CN112044268B (en
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李俊杰
魏进超
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Zhongye Changtian International Engineering Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/90—Injecting reactants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen oxides
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/30—Technologies for a more efficient combustion or heat usage

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Abstract

The invention provides a method and a system for utilizing heat energy in flue gas treatment, wherein flue gas with higher temperature after desulfurization is used as combustion-supporting gas, oxygen components in the flue gas after desulfurization under the high-temperature condition are utilized, the flue gas after desulfurization is used as combustion-supporting gas and fuel to be combusted in a hot blast stove, and the high-temperature environment and high oxygen content of the part of gas are used as the combustion-supporting gas, so that the use of energy is greatly saved; simultaneously, utilize the carbon monoxide that contains in the flue gas behind the desulfurization, carbon monoxide further burns in the combustion furnace and gives out the heat, utilizes the active ingredient in the waste gas to produce the heat, and this heat also is used for raising the temperature to the flue gas that gets into denitration treatment system, and the energy saving makes full use of active ingredient reduces the emission of carbon monoxide pollutant simultaneously.

Description

Method and system for utilizing heat energy in flue gas treatment
Technical Field
The invention relates to a flue gas treatment method and a flue gas treatment system, in particular to a method and a system for utilizing heat energy in flue gas treatment, and belongs to the technical field of flue gas treatment.
Background
Sintering is a fundamental link in the iron and steel industry, and the amount of waste gas discharged is large (about 2000-3000 Nm)3T (sinter)), large temperature fluctuation (120-3) The pollutant component is complex, including SO2、NOxDioxins, dusts, heavy metals, fluorides, etc., in which SO2、NOxDioxin and dust respectively account for 70%, 48%, 90% and 40% of the total amount of the air pollutant discharged in the steel industry, and sulfur resource waste and environmental pollution such as acid rain, haze and the like are caused, so that the method is the key and difficult point of air pollution control. The desulfurization of sintering flue gas has been widely popularized and generally classified into a semi-dry method, a wet method and a dry method, wherein the semi-dry method is represented by a circulating fluidized bed method (CFB) and a rotary spray drying method (SDA), the dry method is represented by an activated carbon process, and the wet method is mainly a limestone-gypsum method. With the arrival of ultra-low emission, NO in the sintering flue gas is treatedxThe emission of the catalyst provides a new requirement, the Selective Catalytic Reduction (SCR) technology is the denitration technology which is most widely applied and has the most mature technology at present, but the temperature window of the activated carbon for SCR denitration is between 180 ℃ and 400 ℃ and is higher than the emission temperature of sintering flue gas, so the sintering flue gas needs to be heated for denitration.
In the prior art, a single-stage activated carbon method and SCR process flow is shown in figure 1, a small amount of ammonia can be sprayed in flue gas entering an activated carbon purification device, sulfur dioxide, dioxin and other organic matters in the flue gas are mainly removed, and the desorbed sulfur-rich gas is sent to a resource treatment device to be prepared into sulfuric acid or other products; and (4) conveying the flue gas after primary purification into an SCR reactor. Because the temperature of the flue gas does not exceed 150 ℃ generally, the temperature of the flue gas is required to be raised to over 180 ℃ at the inlet of the SCR reactor by adopting a GGH device, and the flue gas after deep purification reaches the ultralow emission standard and then is discharged into the atmosphere.
In the prior art, the process flow of the semi-dry method and the SCR is shown in FIG. 2, raw flue gas enters an SCR reactor after passing through a desulfurizing tower and a dust remover, and because the flue gas temperature is lower (about 90 ℃) after desulfurization, the flue gas is heated before entering the SCR and the reactor no matter middle-temperature SCR or low-temperature SCR is adopted. The common heating method is to arrange a GGH device. And the smoke passes through the SCR reactor and is discharged into the atmosphere after reaching the standard.
In the prior art, the wet desulfurization and SCR process flow is shown in fig. 3, and the original flue gas is first desulfurized by a desulfurization device and then enters an SCR reactor for denitration. After desulfurization, the flue gas has high humidity and low temperature, and the flue gas can enter the SCR reactor only after being heated and heated no matter the SCR reaction catalyst adopts a medium-high temperature type or low-temperature type catalyst. The purified flue gas can be directly discharged into the atmosphere.
In the prior art, the technical scheme of adjusting the temperature of entering the denitration system is shown in fig. 4, the combustion air source of the hot blast stove is BFG/COG, the combustion-supporting gas is air, the air is sent to the flue after desulfurization after combustion of the hot blast stove, and enters the denitration tower after being mixed with the flue gas, so that the target temperature is reached when entering the denitration tower, and the clean flue gas after denitration passes through GGH and flue gas heat exchange in the flue after desulfurization, so that the heat is fully utilized.
For a sintering flue gas desulfurization facility which is built and well operated, an SCR denitration process is generally selected, if wet desulfurization and SCR denitration or semi-dry desulfurization and SCR denitration is adopted, a two-stage mode or a single-stage mode and an SCR process can be selected for a single-stage activated carbon process, wherein the flue gas at the outlet of the wet desulfurization has high humidity and low temperature, and the flue gas can enter an SCR reactor only by heating and raising the temperature; the temperature of the semi-dry desulfurization flue gas outlet is about 100 ℃, and the flue gas also needs to be heated; the temperature of the flue gas at the outlet of the activated carbon method is about 140 ℃, but the SCR denitration temperature window is high, and heating treatment is still needed.
At present, blast furnace gas or coke oven gas is used as a gas source, air is used as combustion-supporting gas, the gas is directly introduced into a flue after being combusted in a combustion furnace, sintering flue gas is heated, the heating gas is subjected to denitration and then exchanges heat with the original flue gas through GGH, and the heat utilization rate is improved2The smoke gas amount of the sintering machine reaches 200 ten thousand Nm3The combustion gases can exchange heat with the sintering original flue gas on one hand, and introduce a large amount of gases (the indirect heat exchange efficiency is low) on the other hand, thereby increasing the empty tower gas velocity entering the SCR reactor and improving the denitration treatment difficultyThe invention starts from the aspect of reducing combustion improver air, and reduces the smoke quantity on the basis of meeting the smoke temperature rise.
Disclosure of Invention
Aiming at the technical problems that in the prior art, the problem of nitrogen oxide in flue gas is solved, the flue gas after desulfurization needs to be input into a denitration treatment system through heating treatment, air and fuel are needed to be used for combustion heating when heating, and a large amount of combustion-supporting gas (air) needs to be consumed when heating the combustion-supporting gas, the flue gas with higher temperature after desulfurization is used as the combustion-supporting gas, oxygen components in the flue gas after desulfurization under a high-temperature condition are used, the flue gas after desulfurization is used as the combustion-supporting gas and the fuel to be combusted in a hot blast stove, and the high-temperature environment and high oxygen content of the part of gas are used as the combustion-supporting gas, so that the energy is greatly saved; simultaneously, utilize the carbon monoxide that contains in the flue gas behind the desulfurization, carbon monoxide further burns in the combustion furnace and gives out the heat, utilizes the active ingredient in the waste gas to produce the heat, and this heat also is used for raising the temperature to the flue gas that gets into denitration treatment system, and the energy saving makes full use of active ingredient reduces the emission of carbon monoxide pollutant simultaneously.
According to a first embodiment of the invention, a method for utilizing heat energy in flue gas treatment is provided.
A method for utilizing heat energy in flue gas treatment comprises the following steps:
1) carrying out desulfurization treatment on the flue gas to obtain desulfurized flue gas;
2) conveying the desulfurized flue gas to a denitration treatment system through a first conveying pipeline for denitration treatment;
3) a branch is divided into a first conveying pipeline and is used as a second conveying pipeline, a part of the desulfurized flue gas conveyed to the denitration treatment system is conveyed to the hot blast stove through the second conveying pipeline, the desulfurized flue gas conveyed to the hot blast stove and fuel are combusted in the hot blast stove to generate high-temperature gas, and the high-temperature gas is conveyed back to the first conveying pipeline through a third conveying pipeline.
Preferably, the flue gas treated by the denitration treatment system is discharged through a fourth conveying pipeline. And heat exchangers are arranged on the first conveying pipeline and the fourth conveying pipeline. The heat exchanger exchanges heat between the first conveying pipeline and the fourth conveying pipeline.
Preferably, step 3) is specifically:
3a) the position of the first conveying pipeline, from which the second conveying pipeline is separated, is located upstream of the connecting position of the heat exchanger and the first conveying pipeline, and the position of the high-temperature gas, which is conveyed back to the first conveying pipeline through the third conveying pipeline, is located downstream of the connecting position of the heat exchanger and the first conveying pipeline; and one part of the desulfurized flue gas is conveyed to the hot blast stove, the rest part of the desulfurized flue gas exchanges heat through the heat exchanger, and the high-temperature flue gas generated by the hot blast stove is mixed with the desulfurized flue gas after heat exchange and is conveyed to the denitration treatment system together.
Preferably, step 3) is specifically:
3b) the position of the first conveying pipeline, from which the second conveying pipeline is separated, is located downstream of the connecting position of the heat exchanger and the first conveying pipeline, and the position of the high-temperature gas, which is conveyed back to the first conveying pipeline through the third conveying pipeline, is located downstream of the connecting position of the heat exchanger and the first conveying pipeline; the position of the first conveying pipeline, from which the second conveying pipeline is separated, is positioned at the upstream of the third conveying pipeline, which is connected with the first conveying pipeline; and after the desulfurized flue gas totally exchanges heat through the heat exchanger, one part of the desulfurized flue gas is conveyed to the hot blast stove, and the high-temperature flue gas generated by the hot blast stove is mixed with the desulfurized flue gas in the first conveying pipeline and conveyed to the denitration treatment system together.
Preferably, step 3) is specifically:
3c) the position of the first conveying pipeline, from which the second conveying pipeline is separated, is located downstream of the connecting position of the heat exchanger and the first conveying pipeline, and the position of the high-temperature gas, which is conveyed back to the first conveying pipeline through the third conveying pipeline, is located downstream of the connecting position of the heat exchanger and the first conveying pipeline; the position of the first conveying pipeline, from which the second conveying pipeline is separated, is positioned at the downstream of the third conveying pipeline, which is connected with the first conveying pipeline; high-temperature flue gas generated by the hot blast stove is mixed with desulfurized flue gas in the first conveying pipeline, one part of the mixed flue gas is conveyed to the hot blast stove, and the rest of the mixed flue gas is conveyed to the denitration treatment system.
Preferably, the temperature T of the flue gas in the first conveying pipeline after heat exchange of the heat exchanger is detected1DEG C; detecting the flow of the desulfurized flue gas in the first conveying pipeline as P1，m3H; setting the temperature T to be reached by the flue gas when the flue gas enters the denitration treatment systemDenitrationDEG C; by calculating:
the heat Q which is C needed by the flue gas when entering the denitration treatment system1*P1*(TDenitration-T1) (ii) a Wherein: c1Is the specific heat capacity of the smoke, Kcal/m3·℃；
The volume of fuel required to provide heat Q, V ═ Q/C2(ii) a Wherein C is2Kcal/m is the combustion value of the fuel3；
Air quantity P required for burning fuel with flow V2，m3/h；
Figure BDA0002084777220000041
Wherein: k is the amount of air required to combust a unit volume of fuel.
Preferably, in the step 3a), the flow rate in the desulfurized flue gas is P2The flue gas is conveyed to a hot blast stove.
Preferably, in the step 3b), after the desulfurized flue gas is subjected to heat exchange through the heat exchanger, the flow of the desulfurized flue gas is P2The flue gas is conveyed to a hot blast stove.
Preferably, in step 3c), the high-temperature flue gas generated by the hot blast stove is mixed with the desulfurized flue gas in the first conveying pipeline, and the flow of the mixed flue gas is P2The flue gas is conveyed to a hot blast stove.
Preferably, the denitration treatment system is an SCR denitration system.
Preferably, the heat exchanger is a GGH heat exchanger.
Preferably, the flue gas is sintering flue gas.
According to a second embodiment provided by the invention, a system for utilizing heat energy in flue gas treatment is provided.
A system for utilizing heat energy in flue gas treatment or treating flue gas denitration by using the method in the first embodiment comprises a denitration treatment system and a hot blast stove. The flue gas is connected to denitration treatment system's air inlet through first pipeline after the desulfurization. A branch of the first conveying pipeline is a second conveying pipeline, and the second conveying pipeline is connected with the first conveying pipeline and an air inlet of the hot blast stove. The air outlet of the hot blast stove is connected to the first conveying pipeline through a third conveying pipeline. The hot blast stove is also provided with a fuel inlet which is connected with a fuel conveying pipeline.
Preferably, the exhaust port of the denitration treatment system is connected to the fourth transfer pipe. And heat exchangers are arranged on the first conveying pipeline and the fourth conveying pipeline.
Preferably, the position of the first conveying pipeline, from which the second conveying pipeline branches, is located upstream of the position of connection of the heat exchanger and the first conveying pipeline. The position of the third conveying pipeline connected with the first conveying pipeline is located downstream of the connecting position of the heat exchanger and the first conveying pipeline.
Preferably, the position of the first conveying pipeline, from which the second conveying pipeline branches off, is located downstream of the position of connection of the heat exchanger with the first conveying pipeline. The position of the third conveying pipeline connected with the first conveying pipeline is located downstream of the connecting position of the heat exchanger and the first conveying pipeline. And the position of the first conveying pipeline which is separated from the second conveying pipeline is positioned at the upstream of the third conveying pipeline which is connected with the first conveying pipeline.
Preferably, the position of the first conveying pipeline, from which the second conveying pipeline branches off, is located downstream of the position of connection of the heat exchanger with the first conveying pipeline. The position of the third conveying pipeline connected with the first conveying pipeline is located downstream of the connecting position of the heat exchanger and the first conveying pipeline. And the position of the first conveying pipeline which is separated from the second conveying pipeline is positioned at the downstream of the third conveying pipeline which is connected with the first conveying pipeline.
Preferably, a flow control valve is provided at a position where the first delivery pipe is connected to the second delivery pipe or on the second delivery pipe. And a temperature detection device and a flow detection device are arranged at the downstream position of the heat exchanger of the first conveying pipeline.
Preferably, the flow control valve controls the amount of flue gas entering the second conveying pipeline to be P2，m3/h。
Figure BDA0002084777220000051
Wherein: k is the amount of air required for combustion of the fuel per unit volume; c1Is the specific heat capacity of the smoke, Kcal/m3·℃；C2Kcal/m is the combustion value of the fuel3；P1M is the flow rate of flue gas after desulfurization3/h；TDenitrationThe temperature of the flue gas required to enter the denitration treatment system is at the temperature of DEG C; t is1Is the temperature of the flue gas after heat exchange by the heat exchanger.
Preferably, the denitration treatment system is an SCR denitration system.
Preferably, the heat exchanger is a GGH heat exchanger.
Preferably, the second conveying pipeline is provided with a combustion fan.
In the prior art, in order to increase the temperature of the flue gas entering the denitration treatment system, a hot blast stove is usually adopted to heat the gas, so that high-temperature gas is generated and mixed with the desulfurized flue gas, and the temperature of the flue gas entering the denitration treatment system is increased. In the hot blast stove, the combustion-supporting gas of burning is the air, because the flue gas handling capacity is big, reach thousands of tons per hour, the hot blast stove needs to produce a large amount of high-temperature gas, therefore, the air quantity consumes greatly, heat a large amount of combustion-supporting gas and need consume a large amount of fuel, in addition, the input of a large amount of combustion-supporting gas, the high-temperature gas who produces behind the hot blast stove mixes with flue gas after the desulfurization, get into denitration treatment system together, improved pending flue gas volume, increased the processing degree of difficulty.
According to the invention, according to the high oxygen content (16-18%) of the sintering flue gas, the desulfurized sintering flue gas is used as combustion-supporting air, the high-temperature condition of the desulfurized flue gas is utilized, the desulfurized high-oxygen content and high-temperature flue gas is used as combustion-supporting gas and is conveyed to a hot blast stove, and the desulfurized flue gas is used as combustion-supporting gas to be combusted with fuel in the hot blast stove to generate high-temperature flue gasAnd mixing the warm gas with other residual desulfurized flue gas, and conveying the mixture to a denitration treatment system. Compared with normal-temperature air, the flue gas after desulfurization has higher temperature, reduces the fuel required for heating combustion-supporting gas, has high temperature rise efficiency, and greatly reduces the consumption of the fuel in the hot blast stove; secondly, one part of the desulfurized flue gas is directly used as combustion-supporting gas, the part of the flue gas is required to pass through a denitration treatment system, and the part of the flue gas is treated by the denitration treatment system after passing through a hot blast stove, so that the flue gas treatment capacity of the denitration treatment system is not increased, the treatment efficiency of the denitration treatment system is greatly improved, the load of the denitration treatment system is reduced, and the operation cost is reduced; in the prior art, the hot blast stove adopts external air as combustion-supporting gas, and the added combustion-supporting gas is processed by a denitration processing system after passing through the hot blast stove, so that the processing capacity of the denitration processing system is increased; thirdly, the flue gas after desulfurization contains about 4000-3The CO in the desulfurized flue gas is partially conveyed to the hot blast stove to be used as combustion-supporting gas, and the CO in the desulfurized flue gas can be oxidized into CO under the high-temperature condition by utilizing the combustion condition in the hot blast stove2The heat is released, and the usage amount of blast furnace gas or coke oven gas is reduced.
The heating gas in the steel sintering generally adopts blast furnace gas or coke oven gas, and when the blast furnace gas is selected, the ratio of the required air amount to the blast furnace gas is about 1: 1; when selecting the coke oven gas, the ratio of the air quantity to the coke oven gas is about 6: 1, in order to guarantee that the gas fully burns, need supply with a large amount of air, the high temperature gas of production will get into the flue, has improved the running cost, has reduced denitration efficiency.
O in desulfurized flue gas2High content (16% -18%), SO2Very low content of (<35mg/Nm3) High CO content (4000-8000 mg/Nm)3) Therefore, the invention adopts the desulfurization raw flue gas with the capacity of combustion air, and has the following advantages: firstly, the temperature of the flue gas after desulfurization is higher than that of air, so that energy can be saved; secondly, the taken out part of desulfurized flue gas enters the denitration front flue again after high-temperature combustion, so that the flue gas volume of a denitration system is not greatly increased; ③ taking out partial desulfurized smokeThe gas accounts for less total amount of the flue gas and does not influence O2The content is changed, so that the denitration cannot be influenced, and the oxygen content can be reduced under the condition that the current ultralow emission reference oxygen content is 16%; and fourthly, CO gas contained in the sintering flue gas is oxidized again under the high-temperature condition to release heat, so that the using amount of the blast furnace gas/coke oven gas can be reduced.
According to the technical scheme, flue gas in a flue after desulfurization and blast furnace gas or coke oven gas are taken and introduced into a hot air furnace for mixed combustion, high-temperature flue gas after combustion is directly introduced into the flue and enters a denitration system, wherein the gas taking point of the flue gas after desulfurization can be respectively selected before heat exchange of a heat exchanger, after heat exchange of the heat exchanger, before mixing of high-temperature gas generated by the hot air furnace, after heat exchange of the heat exchanger and mixing of high-temperature gas generated by the hot air furnace.
Taking desulfurized flue gas before heat exchange of a heat exchanger, wherein the flue gas is directly desulfurized flue gas, the temperature of the flue gas is about 140 ℃, and the oxygen content is about 16%;
and after heat exchange by the heat exchanger and before mixing high-temperature gas generated by the hot blast stove, taking the desulfurized flue gas, wherein the gas taking point is after heat exchange of GGH, the temperature is about 250 ℃, and the oxygen content is about 16%.
After heat exchange by a heat exchanger and high-temperature gas generated by the hot blast stove are mixed, the desulfurized flue gas is taken, the gas is taken at the position of the high-temperature gas at the outlet of the hot blast stove after entering a desulfurized flue, the temperature is about 280 ℃, and the oxygen content is about 16%.
According to the invention, a part of flue gas is taken from the desulfurized flue gas and is conveyed to the hot blast stove to be used as combustion-supporting gas, and the desulfurized flue gas has high oxygen content and high temperature and has the conditions of being used as combustion-supporting air; the desulfurized flue gas is combusted in the hot air furnace to remove oxygen and then returns to the flue again, so that the oxygen content is not increased greatly, and the oxygen content in the flue can be reduced; fully utilizes CO in the desulfurized flue gas, and CO can be converted into CO in the hot blast stove2Heat is released, and the gas consumption is reduced.
At 600m2For example, the flue gas amount is about 200 ten thousand Nm3Adopting an active carbon method and an SCR process, and the flue gas temperature is 140 ℃ after active carbon desulfurizationThe temperature was 280 ℃. The desulfurized flue gas needs to be heated from 140 ℃ to 280 ℃ and then conveyed to a denitration treatment system, so that tens of tons of fuel and tens of tons of combustion-supporting gas are needed per hour. In the prior art, normal temperature air is used as combustion-supporting gas, tens of tons of air per hour need to be heated from about 20 ℃ to 280 ℃, and a large amount of fuel needs to be consumed for heating the combustion-supporting gas. By adopting the technical scheme of the invention, hundreds of kilograms of fuel can be saved by a single denitration treatment system per hour, thousands of tons of fuel are saved by accumulation per year, and the emission of pollutants is greatly reduced while the energy consumption is saved.
By adopting the technical scheme of the invention, the desulfurized flue gas is taken as combustion-supporting gas before heat exchange of the heat exchanger, and the combustion-supporting gas at about 140 ℃ is heated to 280 ℃. After heat exchange of the heat exchanger and before mixing high-temperature gas generated by the hot blast stove, taking desulfurized flue gas as combustion-supporting gas, and only heating the combustion-supporting gas at about 250 ℃ to 280 ℃. After heat exchange of the heat exchanger and high-temperature gas generated by the hot blast stove are mixed, desulfurized flue gas is taken as combustion-supporting gas, the temperature of the flue gas per se at the position is about 280 ℃, the combustion-supporting gas per se does not need to consume fuel, the use of the fuel is greatly saved, and the pollution of the combustion fuel to the environment is reduced.
The invention utilizes the carbon monoxide component existing (or contained) in the flue gas, the carbon monoxide and oxygen react to generate carbon dioxide, which is an exothermic reaction, the carbon monoxide in the flue gas is converted into carbon dioxide through the hot blast stove, and the heat released by the reaction is used for heating the desulfurized flue gas, thereby realizing the effect of heating the desulfurized flue gas; meanwhile, the carbon monoxide in the flue gas is removed, and the pollution of the carbon monoxide in the flue gas to the environment is avoided.
According to the invention, as a preferable scheme, the heat quantity required to be provided for the desulfurized flue gas can be calculated according to the temperature of the flue gas in the first conveying pipeline after heat exchange by the heat exchanger, the flow rate of the desulfurized flue gas in the first conveying pipeline and the proper denitration temperature set according to the process requirement of the denitration treatment system. Then, according to the type of the fuel, the combustion value of the fuel is known, and the fuel required for providing the heat can be calculated; and the required combustion-supporting gas quantity can be obtained according to the combustion quantity of the fuel. Through accurate calculation, quantitative combustion-supporting gas who carries fixed quantity in the flue gas after the desulfurization reaches the hot-blast furnace in, produces high-temperature gas with the fuel burning, and the high-temperature gas that the burning produced mixes with other flue gas after the desulfurization, promotes the temperature of the flue gas that gets into denitration processing system to guarantee denitration efficiency.
In the invention, the upstream and the downstream are set according to the flow direction of the smoke, the position through which the smoke flows first is the upstream, and the position through which the smoke flows later is the downstream.
Wherein: the height of the denitration treatment system is 10 to 80m, preferably 15 to 60m, and more preferably 20 to 40 m.
The second transfer line has an internal diameter of 5 to 100%, preferably 10 to 95%, more preferably 20 to 90% of the internal diameter of the first transfer line.
Compared with the prior art, the technical scheme of the invention has the following beneficial technical effects:
1. the invention adopts the flue gas with higher temperature after desulfurization as combustion-supporting gas, utilizes the oxygen component in the flue gas after desulfurization under the high-temperature condition, takes the flue gas after desulfurization as the combustion-supporting gas to be combusted with fuel in the hot blast stove, and utilizes the high-temperature environment and high oxygen content of the part of gas as the combustion-supporting gas, thereby greatly saving the energy;
2. carbon monoxide contained in the desulfurized flue gas is further combusted in the hot air furnace to release heat, effective components in the waste gas are used for generating heat, and the heat is also used for heating the flue gas entering the denitration treatment system, so that energy is saved, the effective components are fully utilized, and the emission of carbon monoxide pollutants is reduced;
3. the technical scheme of the invention is easy to realize, only one pipeline shell needs to be added, the denitration system and the hot air system run synchronously, the working condition is good, and the utilization rate of the desulfurized flue gas is high.
Drawings
FIG. 1 is a flow diagram of a prior art single-stage activated carbon + SCR process;
FIG. 2 is a flow chart of a semi-dry + SCR process in the prior art;
FIG. 3 is a flow chart of a prior art wet desulfurization + SCR process;
FIG. 4 is a process flow diagram of a prior art solution for regulating the temperature of the feed to the denitrification system;
FIG. 5 is a process flow diagram of a method for utilizing heat energy in flue gas treatment according to the present invention;
FIG. 6 is a process flow chart of a second embodiment of the method for utilizing heat energy in flue gas treatment according to the present invention;
FIG. 7 is a process flow diagram of a third embodiment of the method for utilizing heat energy in flue gas treatment according to the present invention;
FIG. 8 is a process flow diagram of a fourth embodiment of the method for utilizing heat energy in flue gas treatment according to the present invention;
FIG. 9 is a schematic structural view of a heat energy utilization system in flue gas treatment according to the present invention;
FIG. 10 is a schematic structural view of a heat energy utilization system in flue gas treatment according to a second embodiment of the present invention;
FIG. 11 is a schematic structural view of a heat energy utilization system in flue gas treatment according to a third embodiment of the present invention;
FIG. 12 is a schematic structural diagram of a fourth embodiment of a heat energy utilization system in flue gas treatment according to the present invention.
Reference numerals:
1: a denitration treatment system; 2: a hot blast stove; 3: a heat exchanger; 4: a flow control valve; 5: a temperature detection device; 6: a flow detection device; 7: a combustion fan; l1: a first delivery conduit; l2: a second delivery line; l3: a third delivery line; l4: a fourth delivery conduit; l5: a fuel delivery conduit.
Detailed Description
A heat energy utilization system in flue gas treatment comprises a denitration treatment system 1 and a hot blast stove 2. The desulfurized flue gas is connected to the air inlet of the denitration treatment system 1 through the first conveying pipeline L1. The first conveying pipeline L1 branches into a second conveying pipeline L2, and the second conveying pipeline L2 is connected with the first conveying pipeline L1 and the air inlet of the hot blast stove 2. The air outlet of the hot blast stove 2 is connected to a first conveying pipe L1 through a third conveying line L3. The hot blast stove 2 is also provided with a fuel inlet which is connected with a fuel conveying pipeline L5.
Preferably, the exhaust port of the denitration treatment system 1 is connected to the fourth transfer line L4. The first conveying pipeline L1 and the fourth conveying pipeline L4 are provided with heat exchangers 3.
Preferably, the position at which the first transfer line L1 branches off the second transfer line L2 is upstream of the position at which the heat exchanger 3 is connected to the first transfer line L1. The position at which the third transfer line L3 connects to the first transfer line L1 is downstream of the position at which the heat exchanger 3 connects to the first transfer line L1.
Preferably, the point at which the first transfer line L1 branches off the second transfer line L2 is downstream of the point at which the heat exchanger 3 is connected to the first transfer line L1. The position at which the third transfer line L3 connects to the first transfer line L1 is downstream of the position at which the heat exchanger 3 connects to the first transfer line L1. And the position at which the first delivery conduit L1 branches off the second delivery conduit L2 is upstream of the connection of the third delivery conduit L3 to the first delivery conduit L1.
Preferably, the point at which the first transfer line L1 branches off the second transfer line L2 is downstream of the point at which the heat exchanger 3 is connected to the first transfer line L1. The position at which the third transfer line L3 connects to the first transfer line L1 is downstream of the position at which the heat exchanger 3 connects to the first transfer line L1. And the position at which the first delivery conduit L1 branches off the second delivery conduit L2 is downstream of the connection of the third delivery conduit L3 to the first delivery conduit L1.
Preferably, the flow control valve 4 is provided at a position where the first transfer line L1 is connected to the second transfer line L2 or at the second transfer line L2. The first delivery pipe L1 is provided with a temperature detection device 5 and a flow rate detection device 6 at a position downstream of the heat exchanger 3.
Preferably, the flow control valve 4 controls the amount of flue gas entering the second conveying pipeline L2 to be P2，m3/h。
Figure BDA0002084777220000091
Wherein: k is unit volume fuelThe amount of air required for combustion of the material; c1Is the specific heat capacity of the smoke, Kcal/m3·℃；C2Kcal/m is the combustion value of the fuel3；P1M is the flow rate of flue gas after desulfurization3/h；TDenitrationThe temperature of the flue gas required to be reached when the flue gas enters the denitration treatment system is at the temperature of DEG C; t is1Is the temperature of the flue gas after heat exchange by the heat exchanger.
Preferably, the denitration treatment system 1 is an SCR denitration system.
Preferably, the heat exchanger 3 is a GGH heat exchanger.
Preferably, the second transfer line L2 is provided with a combustion fan 7.
The technical solution of the present invention is illustrated below, and the claimed scope of the present invention includes, but is not limited to, the following examples.
Example 1
As shown in FIG. 9, a system for utilizing heat energy in flue gas treatment or treating flue gas denitration by using the method in the first embodiment comprises a denitration treatment system 1 and a hot blast stove 2. The desulfurized flue gas is connected to the air inlet of the denitration treatment system 1 through the first conveying pipeline L1. The first conveying pipeline L1 branches into a second conveying pipeline L2, and the second conveying pipeline L2 is connected with the first conveying pipeline L1 and the air inlet of the hot blast stove 2. The air outlet of the hot blast stove 2 is connected to a first conveying pipe L1 through a third conveying line L3. The hot blast stove 2 is also provided with a fuel inlet which is connected with a fuel conveying pipeline L5. The denitration treatment system 1 is an SCR denitration system.
Example 2
As shown in FIG. 10, a system for utilizing heat energy in flue gas treatment or treating flue gas denitration by using the method in the first embodiment comprises a denitration treatment system 1 and a hot blast stove 2. The desulfurized flue gas is connected to the air inlet of the denitration treatment system 1 through the first conveying pipeline L1. The first conveying pipeline L1 branches into a second conveying pipeline L2, and the second conveying pipeline L2 is connected with the first conveying pipeline L1 and the air inlet of the hot blast stove 2. The air outlet of the hot blast stove 2 is connected to a first conveying pipe L1 through a third conveying line L3. The hot blast stove 2 is also provided with a fuel inlet which is connected with a fuel conveying pipeline L5. The exhaust port of the denitration treatment system 1 is connected to a fourth transfer line L4. The first conveying pipeline L1 and the fourth conveying pipeline L4 are provided with heat exchangers 3. The heat exchanger 3 is a GGH heat exchanger.
The position at which the first transfer line L1 branches off the second transfer line L2 is upstream of the position at which the heat exchanger 3 is connected to the first transfer line L1. The position at which the third transfer line L3 connects to the first transfer line L1 is downstream of the position at which the heat exchanger 3 connects to the first transfer line L1. The second conveying pipeline L2 is provided with a combustion fan 7.
Example 3
As shown in fig. 11, example 2 was repeated except that the position at which the first transfer line L1 branches off the second transfer line L2 was located downstream of the position at which the heat exchanger 3 was connected to the first transfer line L1. The position at which the third transfer line L3 connects to the first transfer line L1 is downstream of the position at which the heat exchanger 3 connects to the first transfer line L1. And the position at which the first delivery conduit L1 branches off the second delivery conduit L2 is upstream of the connection of the third delivery conduit L3 to the first delivery conduit L1.
Example 4
As shown in fig. 12, example 2 was repeated except that the position at which the first transfer line L1 branches off the second transfer line L2 was located downstream of the position at which the heat exchanger 3 was connected to the first transfer line L1. The position at which the third transfer line L3 connects to the first transfer line L1 is downstream of the position at which the heat exchanger 3 connects to the first transfer line L1. And the position at which the first delivery conduit L1 branches off the second delivery conduit L2 is downstream of the connection of the third delivery conduit L3 to the first delivery conduit L1.
Example 5
Example 4 was repeated except that the flow control valve 4 was provided on the second feed line L2 or the position where the first feed line L1 was connected to the second feed line L2. The first delivery pipe L1 is provided with a temperature detection device 5 and a flow rate detection device 6 at a position downstream of the heat exchanger 3. The flow control valve 4 controls the smoke gas amount entering the second conveying pipeline L2 to be P2，m3/h。
Figure BDA0002084777220000101
Wherein: k is the amount of air required for combustion of the fuel per unit volume; c1Is the specific heat capacity of the smoke, Kcal/m3·℃；C2Kcal/m is the combustion value of the fuel3；P1M is the flow rate of flue gas after desulfurization3/h；TDenitrationThe temperature of the flue gas required to be reached when the flue gas enters the denitration treatment system is at the temperature of DEG C; t is1Is the temperature of the flue gas after heat exchange by the heat exchanger.
Example 6
As shown in fig. 5, a method for utilizing heat energy in flue gas treatment comprises the following steps:
1) carrying out desulfurization treatment on the sintering flue gas to obtain desulfurized flue gas;
2) conveying the desulfurized flue gas to a denitration treatment system 1 through a first conveying pipeline L1 for denitration treatment;
3) first pipeline L1 divides a branch road to be second pipeline L2, and the flue gas after carrying to the desulfurization of denitration treatment system divides partly to carry to hot-blast furnace 2 via second pipeline L2, carries the flue gas after the desulfurization and the fuel of hot-blast furnace to burn in hot-blast furnace 2, produces high temperature gas, and high temperature gas carries back first pipeline L1 through third pipeline L3.
Example 7
As shown in fig. 6, a method for utilizing heat energy in flue gas treatment comprises the following steps:
1) carrying out desulfurization treatment on the sintering flue gas to obtain desulfurized flue gas;
2) conveying the desulfurized flue gas to a denitration treatment system 1 through a first conveying pipeline L1 for denitration treatment;
3a) the position of the first conveying pipeline L1, from which the second conveying pipeline L2 branches off, is upstream of the position of the connection of the heat exchanger 3 and the first conveying pipeline L1, and the position of the high-temperature gas conveyed back to the first conveying pipeline L1 through the third conveying pipeline L3 is downstream of the position of the connection of the heat exchanger 3 and the first conveying pipeline L1; one part of the desulfurized flue gas is conveyed to the hot blast stove 2, the rest part of the desulfurized flue gas exchanges heat through the heat exchanger 3, and the high-temperature flue gas generated by the hot blast stove 2 is mixed with the desulfurized flue gas after heat exchange and is conveyed to the denitration treatment system 1 together.
The flue gas treated by the denitration treatment system 1 is discharged through a fourth conveying pipeline L4. The first conveying pipeline L1 and the fourth conveying pipeline L4 are provided with heat exchangers 3. The heat exchanger 3 exchanges heat between the first transfer duct L1 and the fourth transfer duct L4.
The temperature T of the flue gas in the first conveying pipeline L1 after heat exchange of the heat exchanger 3 is detected1DEG C; detecting the flow of the desulfurized flue gas in the first conveying pipeline L1 as P1，m3H; the temperature T of the flue gas to be reached when the flue gas enters the denitration treatment system 1 is setDenitrationDEG C; by calculating:
the heat Q which is C needed by the flue gas when the flue gas enters the denitration treatment system 11*P1*(TDenitration-T1) (ii) a Wherein: c1Is the specific heat capacity of the smoke, Kcal/m3·℃；
The volume of fuel required to provide heat Q, V ═ Q/C2(ii) a Wherein C is2Kcal/m is the combustion value of the fuel3；
Air quantity P required for burning fuel with flow V2，m3/h；
Figure BDA0002084777220000111
Wherein: k is the amount of air required to combust a unit volume of fuel.
In the step 3a), the flow in the desulfurized flue gas is P2The flue gas is conveyed to the hot blast stove 2.
Example 8
As shown in fig. 7, example 7 is repeated except that step 3a) is replaced by:
3b) the position of the first conveying pipeline L1, from which the second conveying pipeline L2 branches off, is downstream of the position of the connection of the heat exchanger 3 and the first conveying pipeline L1, and the position of the high-temperature gas conveyed back to the first conveying pipeline L1 through the third conveying pipeline L3 is downstream of the position of the connection of the heat exchanger 3 and the first conveying pipeline L1; and the position at which the first delivery duct L1 branches off the second delivery duct L2 is upstream of the connection of the third delivery duct L3 to the first delivery duct L1; after the desulfurized flue gas is subjected to heat exchange through the heat exchanger 3, one part of the desulfurized flue gas is conveyed to the hot blast stove 2, and the high-temperature flue gas generated by the hot blast stove 2 is mixed with the desulfurized flue gas in the first conveying pipeline L1 and is conveyed to the denitration treatment system 1 together.
The temperature T of the flue gas in the first conveying pipeline L1 after heat exchange of the heat exchanger 3 is detected1DEG C; detecting the flow of the desulfurized flue gas in the first conveying pipeline L1 as P1，m3H; the temperature T of the flue gas to be reached when the flue gas enters the denitration treatment system 1 is setDenitrationDEG C; by calculating:
the heat Q which is C needed by the flue gas when the flue gas enters the denitration treatment system 11*P1*(TDenitration-T1) (ii) a Wherein: c1Is the specific heat capacity of the smoke, Kcal/m3·℃；
The volume of fuel required to provide heat Q, V ═ Q/C2(ii) a Wherein C is2Kcal/m is the combustion value of the fuel3；
Air quantity P required for burning fuel with flow V2，m3/h；
Figure BDA0002084777220000121
Wherein: k is the amount of air required to combust a unit volume of fuel.
In the step 3b), after the desulfurized flue gas is subjected to heat exchange through the heat exchanger 3, the flow of the desulfurized flue gas is P2The flue gas is conveyed to the hot blast stove 2.
Example 9
As shown in fig. 8, example 7 is repeated except that step 3a) is replaced by:
3c) the position of the first conveying pipeline L1, from which the second conveying pipeline L2 branches off, is downstream of the position of the connection of the heat exchanger 3 and the first conveying pipeline L1, and the position of the high-temperature gas conveyed back to the first conveying pipeline L1 through the third conveying pipeline L3 is downstream of the position of the connection of the heat exchanger 3 and the first conveying pipeline L1; and the position at which the first delivery duct L1 branches off the second delivery duct L2 is downstream of the connection of the third delivery duct L3 to the first delivery duct L1; the high-temperature flue gas that hot-blast furnace 2 produced mixes with the flue gas behind the desulfurization in the first pipeline L1, and a part in the flue gas after mixing is carried to hot-blast furnace 2, and remaining mixed flue gas is carried to denitration treatment system 1.
The temperature T of the flue gas in the first conveying pipeline L1 after heat exchange of the heat exchanger 3 is detected1DEG C; detecting the flow of the desulfurized flue gas in the first conveying pipeline L1 as P1，m3H; the temperature T of the flue gas to be reached when the flue gas enters the denitration treatment system 1 is setDenitrationDEG C; by calculating:
the heat Q which is C needed by the flue gas when the flue gas enters the denitration treatment system 11*P1*(TDenitration-T1) (ii) a Wherein: c1Is the specific heat capacity of the smoke, Kcal/m3·℃；
The volume of fuel required to provide heat Q, V ═ Q/C2(ii) a Wherein C is2Kcal/m is the combustion value of the fuel3；
Air quantity P required for burning fuel with flow V2，m3/h；
Figure BDA0002084777220000131
Wherein: k is the amount of air required to combust a unit volume of fuel.
In the step 3c), the high-temperature flue gas generated by the hot blast stove 2 is mixed with the desulfurized flue gas in the first conveying pipeline L1, and the flow of the mixed flue gas is P2The flue gas is conveyed to the hot blast stove 2.
At 600m2For example, the flue gas amount is about 200 ten thousand Nm3And h, adopting an activated carbon method and an SCR process, wherein the flue gas temperature is 140 ℃ and the target temperature is 280 ℃ after activated carbon desulfurization.
An experiment is carried out by adopting the technical scheme of the embodiment 7, and the temperature T of the flue gas in the first conveying pipeline L1 after heat exchange of the heat exchanger 3 is detected1At 250 ℃; detecting the flow P of the desulfurized flue gas in the first conveying pipeline L11Is 200 ten thousand meters3H; the temperature T which the flue gas needs to reach when entering the denitration treatment system 1 is setDenitrationIs 280 ℃; wherein the specific heat capacity of the sintering flue gas is1.3376kJ/(Nm3(. degree. C.) or (0.32 Kcal/m)3DEG C), the heat value of blast furnace gas is 3182kJ/m3(or 760 Kcal/m)3) Calorific value of coke oven gas 16720kJ/m3(or 4000 Kcal/m)3)。
By calculating:
firstly, heating flue gas entering a denitration treatment system by adopting blast furnace gas:
calculating the heat required for heating the flue gas to 30 ℃:
Q＝2000000*0.32*30＝1.92*107Kcal/h；
the amount of blast furnace gas required to provide heat to Q:
V＝1.92*107/760＝25263m3/h；
1m when the combustion air is air3The air quantity is 0.92m when the blast furnace gas is completely combusted3Then, the amount of consumed air is required:
P2＝25263*0.92＝23242m3/h；
the desulphurised flue gas upstream of the point where the heat exchanger 3 is connected to the first duct L1 is taken at a heat balance where the temperature of the desulphurised flue gas is 140 ℃. The heat brought by the desulfurized flue gas is the heat required by heating the combustion air, and meanwhile, the heat brought by the desulfurized flue gas is equal to the heat reduced (saved) by the blast furnace gas, and the initial temperature of the combustion air is assumed to be 20 ℃, so that the blast furnace gas volume is saved:
Q1＝23242*1.3376*(140-20)/3182＝1172.8m3/h；
saving blast furnace gas by 100 percent (1172.8/25263) and 4.6 percent;
saving standard coal per hour:
m＝1172.8*760/7000＝127.3kg；
standard coal can be saved each year:
M＝127.3*24*365＝1115t。
secondly, heating the flue gas entering the denitration treatment system by adopting coke oven gas:
V＝1.92*107/4000＝4800m3/h；
combustion air samplingIn the case of air, 1m is common3The air quantity is 5.5m when the blast furnace gas is completely combusted3：
Q3＝4800*5.5＝26399m3/h；
According to the heat balance, the heat brought by the flue gas after sintering desulfurization is the heat required by heating the combustion air, and the heat brought by the flue gas after sintering desulfurization is equal to the heat reduced by the blast furnace gas, and the initial temperature of the combustion air is assumed to be 20 ℃, so that the blast furnace gas amount is saved:
Q4＝26399*1.3376*(140-20)/16720＝253.4m3/h；
the percentage of saved coke oven gas eta' is 253.4/4800 x 100% is 5.3%.
The technical scheme of embodiment 8 is used for carrying out experiments, and the temperature T of the flue gas in the first conveying pipeline L1 after heat exchange of the heat exchanger 3 is detected1At 250 ℃; detecting the flow P of the desulfurized flue gas in the first conveying pipeline L11Is 200 ten thousand meters3H; the temperature T which the flue gas needs to reach when entering the denitration treatment system 1 is setDenitrationIs 280 ℃; wherein the specific heat capacity of the sintering flue gas is 1.3376 kJ/(Nm)3(. degree. C.) or (0.32 Kcal/m)3DEG C), the heat value of blast furnace gas is 3182kJ/m3(or 760 Kcal/m)3) Calorific value of coke oven gas 16720kJ/m3(or 4000 Kcal/m)3)。
By calculating:
firstly, heating flue gas entering a denitration treatment system by adopting blast furnace gas:
calculating the heat required for heating the flue gas to 30 ℃:
Q＝2000000*0.32*30＝1.92*107Kcal/h；
the amount of blast furnace gas required to provide heat to Q:
V＝1.92*107/760＝25263m3/h；
1m when the combustion air is air3The air quantity is 0.92m when the blast furnace gas is completely combusted3Yield 1.8m3Exhaust gas, then the amount of consumed air is required:
P2＝25263*0.92＝23242m3/h；
according to the heat balance, the heat exchanger 3 is taken out of the desulfurized flue gas downstream of the connection position of the first conveying pipeline L1, and the position of the first conveying pipeline L1 branched off from the second conveying pipeline L2 is positioned upstream of the connection position of the third conveying pipeline L3 and the first conveying pipeline L1. The temperature of the desulphurised flue gas at this location was 250 ℃. The heat brought by the desulfurized flue gas is the heat required by heating the combustion air, and meanwhile, the heat brought by the desulfurized flue gas is equal to the heat reduced (saved) by the blast furnace gas, and the initial temperature of the combustion air is assumed to be 20 ℃, so that the blast furnace gas volume is saved:
Q1＝23242*1.3376*(250-20)/3182＝2247.1m3/h；
saving blast furnace gas by 8.9% in 100% of 2247.1/25263;
saving standard coal per hour:
m＝2247.1*760/7000＝244kg；
standard coal can be saved each year:
M＝244*24*365＝2137t。
secondly, heating the flue gas entering the denitration treatment system by adopting coke oven gas:
V＝1.92*107/4000＝4800m3/h；
when the combustion air of the coke oven gas is air, the air is generally 1m3The air quantity is 5.5m when the blast furnace gas is completely combusted3：
Q3＝4800*5.5＝26399m3/h；
According to the heat balance, the heat brought by the flue gas after sintering desulfurization is the heat required by heating the combustion air, and the heat brought by the flue gas after sintering desulfurization is equal to the heat reduced by the blast furnace gas, and the initial temperature of the combustion air is assumed to be 20 ℃, so that the blast furnace gas amount is saved:
Q4＝26399*1.3376*(250-20)/16720＝485.7m3/h；
the percentage eta' of the coke oven gas is 485.7/4800 100 percent to 10.1 percent.
An experiment is carried out by adopting the technical scheme of the embodiment 9, and the temperature T of the flue gas in the first conveying pipeline L1 after heat exchange of the heat exchanger 3 is detected1At 250 ℃; detecting a first delivery conduitFlow rate P of desulfurized flue gas in L11Is 200 ten thousand meters3H; the temperature T which the flue gas needs to reach when entering the denitration treatment system 1 is setDenitrationIs 280 ℃; wherein the specific heat capacity of the sintering flue gas is 1.3376 kJ/(Nm)3(. degree. C.) or (0.32 Kcal/m)3DEG C), the heat value of blast furnace gas is 3182kJ/m3(or 760 Kcal/m)3) Calorific value of coke oven gas 16720kJ/m3(or 4000 Kcal/m)3)。
By calculating:
firstly, heating flue gas entering a denitration treatment system by adopting blast furnace gas:
calculating the heat required for heating the flue gas to 30 ℃:
Q＝2000000*0.32*30＝1.92*107Kcal/h；
the amount of blast furnace gas required to provide heat to Q:
V＝1.92*107/760＝25263m3/h；
1m when blast furnace gas combustion air is taken as air3The air quantity is 0.92m when the blast furnace gas is completely combusted3Then, the amount of consumed air is required:
P2＝25263*0.92＝23242m3/h；
according to the heat balance, the heat exchanger 3 is taken downstream of the connection position of the first conveying pipeline L1, and the position of the first conveying pipeline L1 which is branched off from the second conveying pipeline L2 is positioned at the position of the desulfurized flue gas of the third conveying pipeline L3 which is connected downstream of the first conveying pipeline L1. The temperature of the desulphurised flue gas at this location was 280 ℃. The heat brought by the desulfurized flue gas is the heat required by heating the combustion air, and meanwhile, the heat brought by the desulfurized flue gas is equal to the heat reduced (saved) by the blast furnace gas, and the initial temperature of the combustion air is assumed to be 20 ℃, so that the blast furnace gas volume is saved:
Q1＝23242*1.3376*(280-20)/3182＝2541m3/h；
saving blast furnace gas by 10.1% when the percentage eta of the blast furnace gas is 2541/25263 x 100%;
saving standard coal per hour:
m＝2541*760/7000＝275.9kg；
standard coal can be saved each year:
M＝275.9*24*365＝2416.7t。
secondly, heating the flue gas entering the denitration treatment system by adopting coke oven gas:
V＝1.92*107/4000＝4800m3/h；
when the combustion air is air, the air is generally 1m3The air quantity is 5.5m when the blast furnace gas is completely combusted3：
Q3＝4800*5.5＝26399m3/h；
According to the heat balance, the heat brought by the flue gas after sintering desulfurization is the heat required by heating the combustion air, and the heat brought by the flue gas after sintering desulfurization is equal to the heat reduced by the blast furnace gas, and the initial temperature of the combustion air is assumed to be 20 ℃, so that the blast furnace gas amount is saved:
Q4＝26399*1.3376*(280-20)/16720＝549.1m3/h；
the percentage eta' of the coke oven gas is 549.1/4800 100 percent to 11.4 percent.
In conclusion, the invention can save a large amount of energy, and in addition, CO in the sintering flue gas can be oxidized at high temperature to release heat, and the energy can also be saved.

Claims (10)

1. A method for utilizing heat energy in flue gas treatment comprises the following steps:
1) carrying out desulfurization treatment on the flue gas to obtain desulfurized flue gas;
2) conveying the desulfurized flue gas to a denitration treatment system (1) through a first conveying pipeline (L1) for denitration treatment;
3) first pipeline (L1) divide a branch road to be second pipeline (L2), carry to denitration treatment system's desulfurization back flue gas and divide partly to carry to hot-blast furnace (2) via second pipeline (L2), carry to the flue gas and the fuel burning in hot-blast furnace (2) after the desulfurization of hot-blast furnace, produce high-temperature gas, high-temperature gas carries back first pipeline (L1) through third pipeline (L3).
2. The method for utilizing heat energy in flue gas treatment according to claim 1, wherein: the flue gas after being treated by the denitration treatment system (1) is discharged through a fourth conveying pipeline (L4), a heat exchanger (3) is arranged on the first conveying pipeline (L1) and the fourth conveying pipeline (L4), and the heat exchanger (3) exchanges heat between the first conveying pipeline (L1) and the fourth conveying pipeline (L4).
3. The method for utilizing heat energy in flue gas treatment according to claim 2, wherein: the step 3) is specifically as follows:
3a) the position of the first conveying pipeline (L1) which is divided into the second conveying pipeline (L2) is positioned upstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1), and the position of the high-temperature gas which is conveyed back to the first conveying pipeline (L1) through the third conveying pipeline (L3) is positioned downstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1); one part of the desulfurized flue gas is conveyed to the hot blast stove (2), the rest part of the desulfurized flue gas exchanges heat through the heat exchanger (3), and the high-temperature flue gas generated by the hot blast stove (2) is mixed with the desulfurized flue gas after heat exchange and is conveyed to the denitration treatment system (1) together; or
3b) The position of the first conveying pipeline (L1) which is divided into the second conveying pipeline (L2) is positioned at the downstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1), and the position of the high-temperature gas which is conveyed back to the first conveying pipeline (L1) through the third conveying pipeline (L3) is positioned at the downstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1); and the position at which the first delivery duct (L1) branches off the second delivery duct (L2) is located upstream of the connection of the third delivery duct (L3) to the first delivery duct (L1); after all the desulfurized flue gas is subjected to heat exchange through the heat exchanger (3), one part of the desulfurized flue gas is conveyed to the hot blast stove (2), and the high-temperature flue gas generated by the hot blast stove (2) is mixed with the desulfurized flue gas in the first conveying pipeline (L1) and is conveyed to the denitration treatment system (1) together; or
3c) The position of the first conveying pipeline (L1) which is divided into the second conveying pipeline (L2) is positioned at the downstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1), and the position of the high-temperature gas which is conveyed back to the first conveying pipeline (L1) through the third conveying pipeline (L3) is positioned at the downstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1); and the position at which the first conveying line (L1) branches off the second conveying line (L2) is located downstream of the connection of the third conveying line (L3) to the first conveying line (L1); high-temperature flue gas that hot-blast furnace (2) produced mixes with the flue gas after the desulfurization in first pipeline (L1), and partly carry to hot-blast furnace (2) in the flue gas after the mixture, and remaining mixed flue gas is carried to denitration treatment system (1).
4. The method for utilizing heat energy in flue gas treatment according to claim 3, wherein: detecting the temperature T of the flue gas in the first conveying pipeline (L1) after heat exchange of the heat exchanger (3)1DEG C; detecting the flow P of the desulfurized flue gas in the first conveying pipeline (L1)1，m3H; setting the temperature T of the flue gas to be reached when the flue gas enters the denitration treatment system (1)DenitrationDEG C; by calculating:
the heat Q which is C required by the flue gas when the flue gas enters the denitration treatment system (1)1*P1*(TDenitration-T1) (ii) a Wherein: c1Is the specific heat capacity of the smoke, Kcal/m3·℃；
The volume of fuel required to provide heat Q, V ═ Q/C2(ii) a Wherein C is2Kcal/m is the combustion value of the fuel3；
Air quantity P required for burning fuel with flow V2，m3/h；
Figure FDA0002084777210000021
Wherein: k is the amount of air required for combustion of the fuel per unit volume;
in the step 3a), the flow in the desulfurized flue gas is P2The flue gas is conveyed to a hot blast stove (2); or
In the step 3b), after the desulfurized flue gas is subjected to heat exchange through the heat exchanger (3), the flow of the desulfurized flue gas is P2The flue gas is conveyed to a hot blast stove (2); or
In the step 3c), the high-temperature flue gas generated by the hot blast stove (2) is mixed with the desulfurized flue gas in the first conveying pipeline (L1), and the flow of the mixed flue gas is P2The flue gas is conveyed to a hot blast stove (2).
5. The method for utilizing heat energy in flue gas treatment according to claim 3, wherein: the denitration treatment system (1) is an SCR denitration system; and/or
The heat exchanger (3) is a GGH heat exchanger; and/or
The flue gas is sintering flue gas.
6. A system for utilizing heat energy in flue gas treatment or treating flue gas denitration by using the method of any one of claims 1 to 5, wherein the system comprises a denitration treatment system (1), a hot blast stove (2); the method is characterized in that: the desulfurized flue gas is connected to the gas inlet of the denitration treatment system (1) through a first conveying pipeline (L1), the first conveying pipeline (L1) is divided into a branch line which is a second conveying pipeline (L2), the second conveying pipeline (L2) is connected with the first conveying pipeline (L1) and the gas inlet of the hot blast stove (2), and the gas outlet of the hot blast stove (2) is connected to the first conveying pipeline (L1) through a third conveying pipeline (L3); the hot blast stove (2) is also provided with a fuel inlet which is connected with a fuel conveying pipeline (L5).
7. The heat energy utilization system in flue gas treatment of claim 6, characterized in that: an exhaust port of the denitration treatment system (1) is connected with a fourth conveying pipeline (L4), and a heat exchanger (3) is arranged on the first conveying pipeline (L1) and the fourth conveying pipeline (L4).
8. The heat energy utilization system in flue gas treatment of claim 7, characterized in that: the position of the first conveying pipeline (L1) branching off the second conveying pipeline (L2) is positioned upstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1), and the position of the third conveying pipeline (L3) connecting the first conveying pipeline (L1) is positioned downstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1); or
The position of the first conveying pipeline (L1) branching off the second conveying pipeline (L2) is positioned downstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1), and the position of the third conveying pipeline (L3) connecting the first conveying pipeline (L1) is positioned downstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1); and the position at which the first delivery duct (L1) branches off the second delivery duct (L2) is located upstream of the connection of the third delivery duct (L3) to the first delivery duct (L1); or
The position of the first conveying pipeline (L1) branching off the second conveying pipeline (L2) is positioned downstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1), and the position of the third conveying pipeline (L3) connecting the first conveying pipeline (L1) is positioned downstream of the connecting position of the heat exchanger (3) and the first conveying pipeline (L1); and the position at which the first conveying line (L1) branches off from the second conveying line (L2) is located downstream of the connection of the third conveying line (L3) to the first conveying line (L1).
9. The system for utilizing heat energy in flue gas treatment according to claim 7 or 8, wherein: a flow control valve (4) is arranged at the position where the first conveying pipeline (L1) is connected with the second conveying pipeline (L2) or on the second conveying pipeline (L2), and a temperature detection device (5) and a flow detection device (6) are arranged at the downstream position of the heat exchanger (3) of the first conveying pipeline (L1); the flow control valve (4) controls the smoke gas amount entering the second conveying pipeline (L2) to be P2，m3/h；
Figure FDA0002084777210000031
Wherein: k is the amount of air required for combustion of the fuel per unit volume; c1Is the specific heat capacity of the smoke, Kcal/m3·℃；C2Kcal/m is the combustion value of the fuel3；P1M is the flow rate of flue gas after desulfurization3/h；TDenitrationThe temperature of the flue gas required to be reached when the flue gas enters the denitration treatment system is at the temperature of DEG C; t is1Is the temperature of the flue gas after heat exchange by the heat exchanger.
10. The system for utilizing heat energy in flue gas treatment according to any one of claims 7 to 9, wherein: the denitration treatment system (1) is an SCR denitration system; and/or
The heat exchanger (3) is a GGH heat exchanger; and/or
And a combustion-supporting fan (7) is arranged on the second conveying pipeline (L2).
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