CN112403221A - Flue gas denitration and decarburization treatment system and method - Google Patents

Flue gas denitration and decarburization treatment system and method Download PDF

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CN112403221A
CN112403221A CN201911074328.7A CN201911074328A CN112403221A CN 112403221 A CN112403221 A CN 112403221A CN 201911074328 A CN201911074328 A CN 201911074328A CN 112403221 A CN112403221 A CN 112403221A
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flue gas
reactor
denitration
pipeline
valve
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CN112403221B (en
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叶恒棣
魏进超
刘昌齐
康建刚
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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
    • B01D53/75—Multi-step processes
    • 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
    • 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
    • B01D53/62—Carbon oxides
    • 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
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    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • 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
    • B01D53/8621—Removing nitrogen compounds
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    • B01D53/8631—Processes characterised by a specific device
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
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    • B01D2257/50—Carbon oxides
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    • 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
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
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Abstract

A flue gas denitration and decarbonization treatment system comprises a hot blast stove (1), a CO reactor (2) and an SCR reactor (3); the CO reactor (2) comprises a main reaction tower (201) and a bypass (202); a raw flue gas conveying pipeline (L0) is connected to a flue gas inlet of the SCR reactor (3), a first pipeline (L1) led out from a flue gas outlet of the SCR reactor (3) is divided into a second pipeline (L2) and a third pipeline (L3), and the second pipeline (L2) and the third pipeline (L3) are respectively connected to a main reaction tower (201) and a bypass (202) of the CO reactor (2); the hot blast outlet of the hot blast stove (1) is connected to the second duct (L2) via a fourth duct (L4). The invention avoids the problem that the CO catalyst is easy to inactivate when meeting sulfur oxides in a low-temperature state, and saves the use of fuel.

Description

Flue gas denitration and decarburization treatment system and method
Technical Field
The invention relates to a treatment system and a treatment method for flue gas purification, in particular to a system and a method for flue gas denitration and decarburization treatment, and belongs to the technical field of chemical industry and environmental protection.
Background
For industrial flue gas, in particular for flue gas of sintering machines in the steel industry, the flue gas denitration technology is a flue gas purification technology applied to the chemical industry of generating polynitrogen oxide. Denitration of flue gas, i.e. the removal of NO producedXReduction to N2Thereby removing NO in the smokeXThe method can be divided into wet denitration and dry denitration according to treatment processes. The flue gas denitration technology mainly comprises a dry method (selective catalytic reduction flue gas denitration, selective non-catalytic reduction denitration) and a wet method. Compared with the wet flue gas denitration technology, the dry flue gas denitration technology has the main advantages that: low investment, simple equipment and technological process, and NO removalXThe efficiency is higher, no wastewater and waste treatment is caused, and secondary pollution is not easy to cause. The selective catalytic reduction SCR method denitration adopts ammonia, CO or hydrocarbon and the like as reducing agents under the condition of catalyst existence, and reduces NO in flue gas into N under the condition of oxygen existence2. The denitration by the SCR method is generally controlled at about 120-400 ℃. In the prior art, the temperature of the flue gas to be treated is increased to a suitable denitration temperature range by heating the flue gas and the like, and then denitration is performed. In the process, because the amount of the flue gas to be treated is large, a large amount of fuel is consumed for heating the flue gas to be treated, so that resource waste and secondary environmental pollution are caused.
Moreover, because the flue gas to be treated is generated by the combustion of the fuel, the flue gas contains a certain amount of carbon monoxide because the combustion is sufficient and the fuel cannot be completely and fully combusted. In the prior art, the national emission standard of carbon monoxide is not specifically specified at present, so that the flue gas to be treated is directly discharged after being subjected to desulfurization and denitrification treatment, and the carbon monoxide in the flue gas is not specifically treated and utilized, so that the carbon monoxide is directly discharged. Meanwhile, carbon monoxide is colorless, odorless and nonirritating gas; the solubility in water is very low, and the water is extremely insoluble; the explosion limit of the mixture with air is 12.5 to 74.2 percent; carbon monoxide is easy to combine with hemoglobin to form carboxyhemoglobin, so that the hemoglobin loses the oxygen carrying capacity and function, and the tissues are suffocated and die when the oxygen carrying capacity and function are serious; carbon monoxide has toxic effects on systemic histiocytes, and especially on the cerebral cortex. Therefore, the direct emission of carbon monoxide is very polluting to the environment.
Considering that the catalytic oxidation of carbon monoxide belongs to an exothermic reaction, and the heat released by the reaction can heat the flue gas, the application provides a flue gas denitration system and method using carbon monoxide for synergistic treatment. However, it has been found that carbon monoxide has particularly poor sulfur resistance at low temperatures, and the CO treatment plant is always at a low temperature for some time when the system is turned on. That is, the catalyst in the CO treatment plant is susceptible to poisoning failure by sulfur oxides during cold start-up of the system.
Disclosure of Invention
Aiming at the problem that in the prior art, in the denitration treatment process of flue gas, the flue gas needs to be heated by an external heating system, and then the denitration process can be carried out; in the prior art, carbon monoxide in the flue gas is not treated and is directly discharged; and the catalyst of carbon monoxide has poor sulfur resistance at low temperature, so that the catalyst is easy to inactivate and the like. According to the invention, denitration is performed firstly and then decarburization is performed, and the temperature of the flue gas can rise after denitration, so that denitration and decarburization are performed firstly and then the problem that the CO catalyst is poisoned and loses efficacy when encountering sulfur oxides in a low-temperature state can be avoided.
And in the decarbonization process, carbon monoxide in the flue gas is converted into carbon dioxide, and the heat released in the process is used for heating the original flue gas through the GGH heat exchanger, so that the process of heating the flue gas through external fuel is reduced and even saved.
The CO reactor comprises a main reaction tower and a bypass, and the CO catalyst in the main reaction tower of the CO reactor is preheated by hot air generated by a hot blast stove at the beginning of system start, so that the problem that the CO catalyst is easy to be poisoned and lose efficacy when encountering sulfur oxides in flue gas during cold start of the system is well solved.
The method fully utilizes the carbon monoxide in the flue gas, utilizes the heat emitted in the process of converting the carbon monoxide into the carbon dioxide to achieve the purpose of raising the temperature of the flue gas for denitration treatment, saves or even saves the use of fuel, also avoids the problem that a CO catalyst is easy to inactivate when encountering sulfur oxides in a low-temperature state, simultaneously treats the carbon monoxide in the flue gas, reduces the pollution of the flue gas to the environment, and weakens or even avoids secondary pollution in the process of treating the flue gas.
According to a first embodiment of the invention, a flue gas denitration and decarbonization treatment system is provided.
A flue gas denitration and decarbonization treatment system comprises a hot blast stove, a CO reactor and an SCR reactor. The CO reactor includes a main reaction column and a bypass. The original flue gas conveying pipeline is connected to a flue gas inlet of the SCR reactor, a second pipeline and a third pipeline are branched from a first pipeline led out from a flue gas outlet of the SCR reactor, and the second pipeline and the third pipeline are respectively connected to a main reaction tower and a bypass of the CO reactor. The hot air outlet of the hot blast stove is connected to the second duct via a fourth duct.
Preferably, a fifth pipeline is branched from the fourth pipeline and connected to the original flue gas conveying pipeline.
Preferably, the system further comprises a first valve disposed on the second conduit. The first valve is located upstream of the location where the fourth conduit connects to the second conduit.
Preferably, the system further comprises a second valve disposed on the third conduit.
In the present invention, the system further comprises a GGH heat exchanger. The GGH heat exchanger is arranged between the raw flue gas conveying pipeline and the SCR reactor, the raw flue gas conveying pipeline is connected to a flue gas inlet of a first heat exchange area of the GGH heat exchanger, a flue gas outlet of the first heat exchange area of the GGH heat exchanger is connected to a flue gas inlet of the SCR reactor through a sixth pipeline, and a seventh pipeline led out from a flue gas outlet of a main reaction tower of the CO reactor and an eighth pipeline led out from a bypass of the CO reactor are connected to a second heat exchange area of the GGH heat exchanger through a clean flue gas conveying pipeline after being combined.
Preferably, a third valve is arranged on the fourth pipeline; the third valve is located on the fourth conduit downstream of the location where the fifth conduit branches off.
Preferably, a fourth valve is arranged on the fifth pipeline.
In the present invention, the system further comprises a gas delivery duct connected to a gas supplementary inlet of the stove.
Preferably, the system further comprises a combustion gas delivery duct connected to a combustion gas make-up inlet of the stove.
Preferably, the raw flue gas conveying pipeline is provided with a flue gas flow detection device, a CO concentration detection device and a first temperature detection device; the smoke flow detection device, the CO concentration detection device and the first temperature detection device are all located at the upstream of the connecting position of the fifth pipeline and the original smoke conveying pipeline.
Preferably, a second temperature detection device is arranged on the side wall of the main reaction tower of the CO reactor.
Preferably, a third temperature detection device is arranged on the pipeline close to the flue gas inlet of the SCR reactor.
In the invention, the third temperature detection device is arranged for monitoring the temperature of the flue gas before the flue gas enters the SCR reactor in real time. When the system is not provided with the GGH heat exchanger, the third temperature detection device is arranged on the original flue gas conveying pipeline and is close to the flue gas inlet of the SCR reactor. When the GGH heat exchanger is arranged in the system, the third temperature detection device is arranged on the sixth pipeline and is close to the flue gas inlet of the SCR reactor.
Preferably, the flue gas outlet of the second heat exchange zone of the GGH heat exchanger is connected to the front end of the combustion-supporting gas conveying pipeline.
According to a second embodiment of the invention, a method for removing carbon monoxide and denitration from flue gas is provided.
A method for denitration and decarbonization treatment of flue gas or a method for controlling denitration and carbon monoxide removal of flue gas by using the system comprises the following steps:
1) the first valve is closed, the second valve is opened, and the raw flue gas G is introduced into the raw flue gas conveying pipeline1；
2) Raw flue gas G1Entering an SCR reactor for denitration, wherein the denitrated flue gas enters a bypass of a CO reactor through a third pipeline, and the flue gas is discharged from a flue gas outlet of the bypass of the CO reactor;
3) starting the hot blast stove, opening the third valve, introducing hot blast generated by the hot blast stove into a main reaction tower of the CO reactor, and preheating a CO catalyst in the main reaction tower;
4) the second temperature detection device monitors the temperature of the CO catalyst in the main reaction tower of the CO reactor in real time; when the temperature of the CO catalyst is detected to reach the set temperature T of the catalyst3When the denitration catalyst is used, the first valve is opened, the second valve is closed, the denitrated flue gas enters a main reaction tower of the CO reactor, and contacts with a CO catalyst in the main reaction tower to generate CO catalytic oxidation reaction; the reaction heat released by CO catalytic oxidation heats the flue gas, and the clean flue gas after temperature rise is discharged from a flue gas outlet of a main reaction tower of the CO reactor.
Preferably, step 1) further comprises: and starting the hot blast stove, opening the fourth valve, and inputting hot blast generated by the hot blast stove into the original flue gas conveying pipeline through the fifth pipeline to heat the flue gas in the original flue gas conveying pipeline. And in the step 2), the heated flue gas enters an SCR reactor for denitration.
According to a third embodiment of the invention, a method for removing carbon monoxide and denitration from flue gas is provided.
A method for removing carbon monoxide and denitration from flue gas or a method for controlling the removal of carbon monoxide and denitration from flue gas by using the system comprises the following steps:
1) the first valve is closed, the second valve is opened, and the raw flue gas G is introduced into the raw flue gas conveying pipeline1；
2) Starting the hot blast stove, opening the third valve and the fourth valve, introducing one path of hot air generated by the hot blast stove into the original flue gas conveying pipeline through the fifth pipeline, and heating the flue gas in the original flue gas conveying pipeline;
3) the heated flue gas enters an SCR reactor for denitration after heat exchange through a first heat exchange area of a GGH heat exchanger, the denitrated flue gas enters a bypass of a CO reactor through a third pipeline, and then the flue gas enters a second heat exchange area of the GGH heat exchanger for heat exchange and is discharged;
4) the other path of hot air generated by the hot blast stove is introduced into a main reaction tower of the CO reactor through a fourth pipeline to preheat a CO catalyst in the main reaction tower, and a second temperature detection device monitors the temperature of the CO catalyst in the main reaction tower of the CO reactor in real time; when the temperature of the CO catalyst is detected to reach the set temperature T of the catalyst3When the denitration catalyst is used, the first valve is opened, the second valve is closed, the denitrated flue gas enters a main reaction tower of the CO reactor, and contacts with a CO catalyst in the main reaction tower to generate CO catalytic oxidation reaction; reaction heat released by CO catalytic oxidation heats flue gas, and the heated clean flue gas enters a second heat exchange area of the GGH heat exchanger for heat exchange and then is discharged.
Preferably, in the process of implementing the method for removing carbon monoxide and denitration from flue gas, the raw flue gas G in unit time is detected1Is marked as U1 Nm3H; detecting raw flue gas G1Temperature of (1), denoted as T1DEG C; detecting raw flue gas G1The content of CO in the mixture is marked as P1 g/Nm3(ii) a And (3) calculating: raw gas G in unit time1The mass flow of the medium carbon monoxide is U1*P1g/h; raw gas G in unit time1Heat Q released by combustion of medium carbon monoxide1 kJ/h：
Q1＝a*U1*P1*10.11；
Wherein: a is a combustion coefficient, and the value of a is 0.1-1, preferably 0.4-0.95, and more preferably 0.7-0.9;
calculating the original smoke G1After carbon monoxide in the CO reactor is converted into carbon dioxide in a main reaction tower of the CO reactor, the heat released in the conversion process is used for heating raw flue gas through a GGH heat exchanger, and then the flue gas G containing nitrate enters the SCR reactor2Temperature T of2℃：
Figure BDA0002261920640000041
Wherein: c is the average specific heat capacity of the smoke, kJ/(. degree.C.g); b is a heat transfer coefficient, and the value of b is 0.7-1, preferably 0.8-0.98, and more preferably 0.9-0.95; f is a heat exchange coefficient, and the value of f is 0.7-1, preferably 0.8-0.98, and more preferably 0.9-0.95.
The following analyses were performed:
setting the optimal denitration temperature of the SCR reactor to be T according to the requirements of the SCR reactorDenitration℃；
If T2＝TDenitrationThen the raw flue gas G1The carbon monoxide enters a main reaction tower of a CO reactor for catalytic oxidation, and the released heat enables the nitrate-containing flue gas G entering an SCR reactor2To reach TDenitrationC, directly carrying out denitration treatment on the flue gas in an SCR reactor;
if T2＜TDenitrationIncreasing the consumption of gas and combustion-supporting gas of the hot blast stove to make the nitrate-containing flue gas G entering the SCR reactor2To reach TDenitration℃；
If T2＞TDenitrationThe amount of the fuel gas and the combustion-supporting gas of the hot blast stove is adjusted to be small, so that the nitrate-containing flue gas G entering the SCR reactor2To reach TDenitrationDEG C; if the amount of fuel gas and combustion-supporting gas of the hot blast stove is reduced to the amount after the hot blast stove is shut down, the smoke G containing nitrate2Temperature T of2Is still greater than TDenitrationAt the moment, the second valve is opened to lead part of the original smoke G1A bypass through the CO reactor; the opening degree of the second valve is adjusted, so that the nitrate-containing flue gas G entering the SCR reactor2Down to TDenitration℃。
Preferably, if T2＜TDenitrationThe amount of the fuel gas added to the hot blast stove is as follows:
setting the combustion heat of the gas to N1kJ/g, calculating the mass flow U of the fuel gas to be increased2 Nm3/h：
Figure BDA0002261920640000051
Wherein: e is a combustion coefficient, and the value of the e is 0.6-1, preferably 0.8-0.99, and more preferably 0.8-0.98; that is, the unit time of the supplementary flow rate in the hot blast stove is U2 Nm3H gas to make the temperature of the flue gas reach T before entering the SCR reactorDenitration℃。
Preferably, the smoke G containing the nitrate is generated after the hot blast stove is shut down2Temperature T of2Is still greater than TDenitrationThe regulation of the second valve is specifically as follows:
calculating the flow U of the raw flue gas to be reduced in the main reaction column of a CO reactor3 Nm3/h：
Figure BDA0002261920640000052
That is, the flow rate of the main reaction tower of the CO reactor needs to be reduced to U in unit time3 Nm3H flue gas; the opening degree of the second valve is adjusted to ensure that the flow rate of the flue gas entering a bypass of the CO reactor is U3Nm3H, so that the temperature of the flue gas is reduced to T before entering the SCR reactorDenitration℃。
In the invention, the raw flue gas firstly enters the SCR reactor for denitration, and the denitrated flue gas then enters the CO reactor for carbon monoxide removal. The temperature of the flue gas can rise after denitration, so that denitration is performed before decarburization, and the problem that the CO catalyst is poisoned and loses efficacy when meeting sulfur oxides in a low-temperature state is solved.
In the technical scheme of the invention, the denitration flue gas passes through a CO reactor to convert carbon monoxide in the flue gas into carbon dioxide, and the method specifically comprises the following steps:
2CO+O2＝＝＝＝2CO2。
carbon monoxide in the flue gas is utilized to react with oxygen to generate carbon dioxide, an exothermic reaction is realized, the carbon monoxide in the flue gas is converted into carbon dioxide through a CO reactor, and the heat released by the reaction is utilized to heat the flue gas to be treated through a GGH heat exchanger, so that the effect of heating the flue gas is realized; 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.
In the prior art, the flue gas to be treated often contains sulfur oxides and nitrogen oxides. It has now been found that carbon monoxide has particularly poor sulphur resistance at low temperatures. In the actual production process, a process is required for heating up when the system is started, and the CO treatment device always stays at a low temperature for a period of time. That is, when the system is started, if the flue gas directly enters the CO treatment device, the CO catalyst in the CO treatment device is easily poisoned and deactivated by the sulfur oxides in the flue gas at the same time due to low temperature, and the deactivation of the CO catalyst is irreversible. Aiming at the technical problem, the traditional CO treatment device is designed into a structure comprising a main reaction tower and a bypass, wherein a CO catalyst is arranged in the main reaction tower. When the system is just started, the flue gas after denitration by the SCR reactor does not pass through a main reaction tower of a CO reactor (namely a CO treatment device) but enters a bypass of the CO reactor, and then is discharged. And simultaneously starting the hot blast stove, introducing hot blast generated by the hot blast stove into a main reaction tower of the CO reactor, and heating a CO catalyst in the main reaction tower. When the temperature of the CO catalyst rises to the set temperature T of the CO catalyst3At the moment, the flue gas enters a main reaction tower of the CO reactor for carbon monoxide removal treatment, so that the problem that the CO catalyst is inactivated when encountering sulfur oxides at a low temperature is solved. Generally, the set temperature of the CO catalyst (i.e., the temperature at which the CO catalyst is guaranteed not to deactivate) is related to the type of catalyst.
Compared with the method that hot air generated by the hot blast stove is introduced into the first pipeline to heat the denitrated flue gas, the method has higher heating efficiency. And the first pipeline is introduced to heat all denitrated flue gas, the flue gas treatment amount is large, so a large amount of fuel is consumed for heating the flue gas.
Generally, the temperature range for denitration by the SCR method is 120-400 ℃, but the higher the temperature is, the higher the catalytic efficiency is, on the premise that the SCR catalyst is not deactivated. Therefore, the invention considers that the temperature of the raw flue gas is not high, even if the raw flue gas is heated by the heat released by the conversion of carbon monoxide in the flue gas through the GGH heat exchanger, the temperature of the flue gas before entering the SCR reactor may not reach the optimum denitration temperature of the SCR method, so that one path of hot air generated by the hot blast stove is led into the raw flue gas conveying pipeline to heat the flue gas in the raw flue gas conveying pipeline, thereby ensuring that the flue gas can reach the optimum denitration temperature of the SCR method before entering the SCR reactor and ensuring the denitration efficiency. And the temperature of the original flue gas is increased, so that the flue gas is further ensured to enter the CO reactor, and the CO catalyst is not inactivated due to the fact that the CO catalyst meets sulfur oxides at low temperature.
In the invention, the flue gas carbon monoxide removal and denitration system comprises a hot blast stove, a CO reactor and an SCR reactor. Raw flue gas firstly enters an SCR reactor for denitration, and the denitrated flue gas enters a CO reactor for carbon monoxide removal. The temperature of the flue gas can rise after denitration, so that denitration is performed before decarburization, and the problem that the CO catalyst is poisoned and loses efficacy when meeting sulfur oxides in a low-temperature state is solved. When the denitrated flue gas flows through the CO reactor, CO in the flue gas is oxidized into carbon dioxide to release heat, the released heat heats the clean flue gas, then the clean flue gas exchanges heat with the raw flue gas through the GGH heat exchanger, so that the raw flue gas reaches the temperature required by the SCR method denitration, and then the flue gas enters the SCR reactor to be subjected to denitration treatment. The CO reactor comprises a main reaction tower and a bypass, wherein a CO catalyst is arranged in the main reaction tower. The hot blast stove provided by the invention supplies energy for the CO reactor, and at the beginning of starting the system, hot blast produced by the hot blast stove is used for heating a CO catalyst in a main reaction tower of the CO reactor to a set temperature.
In the method, at the beginning of system startup, when the CO catalyst in the main reaction tower of the CO reactor is in a low-temperature state, the hot blast stove is started, hot blast generated by the hot blast stove enters the main reaction tower of the CO reactor through the fourth pipeline, and the CO catalyst in the main reaction tower is preheated. And at the moment, the first valve is closed, the second valve is opened, and the raw flue gas flows through a bypass of the CO reactor through a third pipeline after being denitrated by the SCR reactor and then is discharged. When the temperature of the CO catalyst in the main reaction tower reaches the catalyst settingTemperature T3(the second temperature detection device carries out real-time monitoring on the temperature of the CO catalyst), the first valve is opened, the second valve is closed, the hot blast stove is closed, the flue gas enters the main reaction tower of the CO reactor and contacts with the CO catalyst to generate CO catalytic oxidation reaction, the heat emitted by the reaction heats the flue gas, and the clean flue gas after temperature rise is discharged from a flue gas outlet of the main reaction tower.
Preferably, considering that the temperature of the raw flue gas may not reach the denitration temperature of the SCR method even after heat released by CO oxidation is transferred to the raw flue gas, the invention leads one path of hot air generated by the hot blast stove to heat the flue gas in the raw flue gas conveying pipeline, and further ensures that the temperature of the flue gas can reach the temperature required by the normal operation of an SCR catalyst before the flue gas enters the SCR reactor. In addition, the flue gas in the original flue gas conveying pipeline is heated by introducing one path of hot air, the temperature of the flue gas is increased, and the condition that the CO catalyst is inactivated because the flue gas enters a main reaction tower of the CO reactor can be avoided. When the temperature of the CO catalyst in the main reaction tower reaches the set temperature T of the catalyst3(the second temperature-detecting device carries out real-time supervision to CO catalyst temperature), open first valve, close the second valve, close the third valve simultaneously, the hot-blast furnace that produces is only used for heating former flue gas this moment, then the flue gas gets into SCR reactor denitration, flue gas after the denitration gets into the main reaction tower of CO reactor, contact with CO catalyst and take place CO catalytic oxidation reaction, the heat that this reaction was emitted heats the flue gas, clean flue gas after the intensification is discharged from the exhanst gas outlet of main reaction tower (or discharge after the heat transfer).
Preferably, the invention also comprises a GGH heat exchanger. The heat released by CO oxidation in the flue gas can be fully utilized by the additional arrangement of the GGH heat exchanger. The reaction heat released by CO catalytic oxidation directly heats the clean flue gas, the heated clean flue gas heats the raw flue gas through the GGH heat exchanger, and the temperature of the raw flue gas is raised, so that the heating effect of the flue gas on the CO catalyst in the main reaction tower is ensured, and the condition that the CO catalyst is inactivated when encountering oxysulfide in a low-temperature state is further ensured. In addition, the temperature of the raw flue gas is increased, so that the temperature of the flue gas can reach the temperature required by denitration by an SCR method more easily before the flue gas enters the SCR reactor.
Preferably, according to the parameters such as the temperature of the raw flue gas, the flow rate of the raw flue gas, the content of carbon monoxide in the raw flue gas and the like, if the heat released by the conversion of the carbon monoxide in the raw flue gas is not enough to raise the temperature of the flue gas to the optimum denitration temperature of the SCR reactor, the temperature is adjusted by external heat (hot blast stove heat supply). In the technical scheme of the invention, the heat released by the conversion of carbon monoxide in the flue gas is preferentially utilized.
In the invention, the raw flue gas G in the raw flue gas conveying pipeline is detected1Flow rate, temperature and raw flue gas G1The content of CO in the flue gas can be obtained1Mass flow of medium carbon monoxide. By conversion, the raw flue gas G per unit time can be calculated1Heat Q released by combustion of medium carbon monoxide1＝a*U1*P1*10.11. Wherein: the combustion coefficient a is because the carbon monoxide is difficult to realize 100% conversion, and can be taken according to engineering experience, and the value is 0.1-1, preferably 0.4-0.95, and more preferably 0.7-0.9. U shape1Is the original smoke G in unit time1Flow rate of (P)1Is raw flue gas G1The content of CO in the mixture. That is, by the technical scheme of the invention, Q can be obtained by utilizing carbon monoxide in the flue gas1The energy of (a).
Further, the energy obtained by converting carbon monoxide in the flue gas is calculated to be Q1kJ/h, calculating the nitrate-containing flue gas G which enters the SCR reactor after the raw flue gas is heated by the GGH heat exchanger by utilizing the energy2Temperature T of2℃。
Figure BDA0002261920640000081
Wherein: detecting raw flue gas G in raw flue gas conveying pipeline through first temperature detection device1Temperature T of1The average specific heat capacity of the smoke, C, kJ/(. degree.C.g), was determined by instrumental detection. The heat transfer coefficient b is because 100% of the heat released by the carbon monoxide converted into carbon dioxide is hardly absorbed by the original flue gas and can be taken according to engineering experience,the value is 0.7-1, preferably 0.8-0.98, more preferably 0.9-0.95. f is a heat exchange coefficient, because the heat exchange proportion of the medium exists in the heat exchange, 100% theoretical heat exchange is difficult to realize, and the value can be obtained according to engineering experience, and is 0.7-1, preferably 0.8-0.98, and more preferably 0.9-0.95. That is, by the technical scheme of the invention, the temperature of the original flue gas can be changed from T to T by utilizing the carbon monoxide in the flue gas1The temperature is increased to T2℃。
In the present invention, the optimum (or optimum) denitration temperature T of the SCR reactor to be selected is known according to the characteristics of the specific SCR reactor, the selection of the denitration process, the denitration catalyst, and the likeDenitrationI.e. knowing the temperature T of the flue gas optimally delivered to the SCR reactorDenitration℃。
By comparing T2And TDenitrationEnsuring the smoke G containing the nitrate2The temperature when entering the SCR reactor to guaranteed the denitration efficiency of the flue gas that contains the nitre in the SCR reactor, nitrogen oxide in the flue gas is got rid of to the utmost extent efficiency, reduces the content of pollutant in the outer exhaust flue gas, thereby reduces the pollution to the environment.
If T2＝TDenitrationThat is, the nitrate-containing flue gas G entering the SCR reactor can be just enabled to enter the SCR reactor by utilizing the heat released by the conversion of the carbon monoxide in the flue gas2To reach TDenitrationAnd C, directly carrying out denitration treatment on the flue gas in the SCR reactor.
If T2＜TDenitrationThat is, the amount of heat released by the conversion of carbon monoxide in the flue gas is not sufficient to drive the nitrate-containing flue gas G entering the SCR reactor2To reach TDenitrationThen the nitrate-containing flue gas G can be brought to a temperature in front of the SCR reactor by additional regulation measures2To reach TDenitrationAnd then delivered to the SCR reactor. The additional adjusting means is to increase the consumption of fuel gas and combustion-supporting gas of the hot blast stove.
According to the selected gas, the combustion heat N of the gas can be known1kJ/g, and the required supplementary flow is U through calculation2 Nm3H gas:
Figure BDA0002261920640000091
wherein: e is a combustion coefficient, because 100% combustion of the fuel is difficult to realize and theoretical 100% heat is difficult to release, the value can be obtained according to engineering experience, and is 0.6-1, preferably 0.8-0.99, and more preferably 0.8-0.98. I.e. a slight excess of gas is introduced, so as to ensure that the temperature of the flue gas reaches T before it enters the SCR reactorDenitration℃。
If T2＞TDenitrationThat is, the flue gas G containing the nitrate is sufficiently lifted by utilizing the heat released by the conversion of carbon monoxide in the flue gas before entering the SCR reactor2To reach TDenitrationDEG C, and heat remains. In the invention, the amount of the fuel gas and the combustion-supporting gas of the hot blast stove is reduced, so that the nitrate-containing flue gas G entering the SCR reactor2To reach TDenitrationDEG C. The third temperature detection device is used for detecting the nitrate-containing flue gas G before entering the SCR reactor2The temperature of the SCR reactor is monitored in real time, and in the process of reducing the consumption of fuel gas and combustion-supporting gas of the hot blast stove, the NOx-containing flue gas G before entering the SCR reactor is combined with a third temperature detection device2Real-time feedback regulation of the temperature.
If the amount of fuel gas and combustion-supporting gas of the hot blast stove is reduced to the amount after the hot blast stove is shut down, the smoke G containing nitrate2Temperature T of2Is still greater than TDenitrationAt the moment, the second valve is opened to lead part of the original smoke G1Flows through a bypass of the CO reactor, thereby leading the nitrate-containing flue gas G entering the SCR reactor2Down to TDenitration℃。
If the hot blast stove is shut down, the smoke G containing nitrate2Temperature T of2Is still greater than TDenitrationThe regulation of the second valve is specifically as follows:
calculating the flow U of the raw flue gas to be reduced in the main reaction column of a CO reactor3 Nm3/h：
Figure BDA0002261920640000092
That is to say a unitIn time, the flow rate of the main reaction tower of the CO reactor needs to be reduced to U3 Nm3H flue gas; the opening degree of the second valve is adjusted to ensure that the flow rate of the flue gas entering a bypass of the CO reactor is U3Nm3H, so that the temperature of the flue gas is reduced to T before entering the SCR reactorDenitration℃。
In the present application, the terms "upstream" and "downstream" are used in relation to the smoke trend.
Compared with the prior art, the invention has the following beneficial technical effects:
1. the CO reactor comprises a main reaction tower and a bypass, wherein the main reaction tower is provided with a CO catalyst, and the CO catalyst in the main reaction tower of the CO reactor is preheated by hot air generated by a hot blast stove at the beginning of starting the system, so that the problem that the CO catalyst is easy to be poisoned and lose efficacy when encountering sulfur oxides in flue gas when the system is started in a cold state is solved;
2. according to the invention, carbon monoxide in the flue gas is converted into carbon dioxide by using the carbon monoxide in the flue gas, the heat emitted in the process directly heats the clean flue gas, and then the clean flue gas heats the original flue gas through the GGH heat exchanger, so that the process of heating the flue gas through external fuel is reduced and even saved;
3. the method treats the carbon monoxide in the flue gas while denitrating, reduces the pollution of the flue gas to the environment, and weakens or even avoids secondary pollution in the flue gas treatment process.
Drawings
FIG. 1 is a schematic structural diagram of a flue gas denitration and decarbonization treatment system according to the present invention;
FIG. 2 is a schematic structural diagram of a flue gas denitration and decarburization treatment system provided with a GGH heat exchanger;
FIG. 3 is a process flow diagram of a denitration and decarbonization treatment method for flue gas according to the present invention;
FIG. 4 is a process flow chart of another method for denitration and decarbonization of flue gas.
Reference numerals:
1: an SCR reactor; 2: a CO reactor; 201: a main reaction tower of the CO reactor; 202: a bypass of the CO reactor; 3: a hot blast stove; 4: a GGH heat exchanger; 401: a first heat transfer zone of the GGH heat exchanger; 402: a second heat transfer zone of the GGH heat exchanger; 5: a flue gas flow rate detection device; 6: a CO concentration detection device; 7: a first temperature detection device; 8: a second temperature detection device; 9: a third temperature detection device; k 1: a first valve; k 2: a second valve; k 3: a third valve; k 4: a fourth valve;
l0: an original flue gas conveying pipeline; l1: a first conduit; l2: a second conduit; l3: a third pipeline; l4: a fourth conduit; l5: a fifth pipeline; l6: a sixth pipeline; l7: a seventh pipe; l8: an eighth conduit; l9: a clean flue gas delivery duct; l10: a gas delivery pipeline; l11: a combustion supporting gas delivery conduit.
Detailed Description
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.
A flue gas denitration and decarbonization treatment system comprises a hot blast stove 1, a CO reactor 2 and an SCR reactor 3. The CO reactor 2 comprises a main reactor column 201 and a bypass 202. The raw flue gas conveying pipeline L0 is connected to the flue gas inlet of the SCR reactor 3, a second pipeline L2 and a third pipeline L3 are branched from a first pipeline L1 led out from the flue gas outlet of the SCR reactor 3, and the second pipeline L2 and the third pipeline L3 are respectively connected to the main reaction tower 201 and the bypass 202 of the CO reactor 2. The hot blast outlet of the stove 1 is connected to a second duct L2 via a fourth duct L4.
Preferably, a fifth pipeline L5 branching from the fourth pipeline L4 is connected to the raw flue gas conveying pipeline L0.
Preferably, the system further comprises a first valve k1 provided on the second pipe L2. The first valve k1 is located upstream of the position where the fourth line L4 is connected to the second line L2.
Preferably, the system further includes a second valve k2 provided on the third pipe L3.
In the present invention, the system further comprises a GGH heat exchanger 4. The GGH heat exchanger 4 is arranged between the raw flue gas conveying pipe L0 connected to the flue gas inlet of the first heat transfer zone 401 of the GGH heat exchanger 4 and the SCR reactor 3, the flue gas outlet of the first heat transfer zone 401 of the GGH heat exchanger 4 is connected to the flue gas inlet of the SCR reactor 3 by a sixth pipe L6, both the seventh pipe L7 leading from the flue gas outlet of the main reactor 201 of the CO reactor 2 and the eighth pipe L8 leading from the bypass 202 of the CO reactor 2 are connected to the second heat transfer zone 402 of the GGH heat exchanger 4 via a clean flue gas conveying pipe L9 after merging.
Preferably, a third valve k3 is provided on the fourth line L4; the third valve k3 is located on the fourth line L4 downstream of the location where the fifth line L5 branches off.
Preferably, a fourth valve k4 is provided in the fifth pipe L5.
In the present invention, the system further comprises a gas delivery duct L10, the gas delivery duct L10 being connected to a gas supplementary inlet of the stove 1.
Preferably, the system further comprises a combustion gas delivery duct L11, the combustion gas delivery duct L11 being connected to a combustion gas make-up inlet of the stove 1.
Preferably, the raw flue gas conveying pipeline L0 is provided with a flue gas flow rate detection device 5, a CO concentration detection device 6, and a first temperature detection device 7; the flue gas flow rate detection device 5, the CO concentration detection device 6 and the first temperature detection device 7 are all positioned at the upstream of the connecting position of the fifth pipeline L5 and the original flue gas conveying pipeline L0.
Preferably, the second temperature detection device 8 is provided on the side wall of the main reaction tower 201 of the CO reactor 2.
Preferably, a third temperature detection device 9 is provided on the pipe close to the flue gas inlet of the SCR reactor 3.
Preferably, the flue gas outlet of the second heat transfer zone 402 of the GGH heat exchanger 4 is connected to the front end of the combustion-supporting gas conveying pipe L11.
Example 1
As shown in fig. 1, a flue gas denitration and decarbonization treatment system comprises a hot blast stove 1, a CO reactor 2 and an SCR reactor 3. The CO reactor 2 comprises a main reactor column 201 and a bypass 202. The raw flue gas conveying pipeline L0 is connected to the flue gas inlet of the SCR reactor 3, a second pipeline L2 and a third pipeline L3 are branched from a first pipeline L1 led out from the flue gas outlet of the SCR reactor 3, and the second pipeline L2 and the third pipeline L3 are respectively connected to the main reaction tower 201 and the bypass 202 of the CO reactor 2. The hot blast outlet of the stove 1 is connected to a second duct L2 via a fourth duct L4. The side wall of the main reaction tower 201 of the CO reactor 2 is provided with a second temperature detection device 8.
Example 2
Example 1 is repeated except that the system further includes a first valve k1 provided on the second pipe L2. The first valve k1 is located upstream of the position where the fourth line L4 is connected to the second line L2. The system further includes a second valve k2 provided on the third pipe L3. The system further comprises a gas delivery duct L10, the gas delivery duct L10 being connected to a gas supplementary inlet of the stove 1. The system further comprises a combustion gas delivery duct L11, the combustion gas delivery duct L11 being connected to a combustion gas make-up inlet of the stove 1.
Example 3
Example 2 was repeated except that a fifth line L5 was branched from the fourth line L4 and connected to the raw flue gas conveying line L0. A third valve k3 is provided in the fourth line L4. The third valve k3 is located on the fourth line L4 downstream of the location where the fifth line L5 branches off. A fourth valve k4 is provided in the fifth pipe L5.
Example 4
As shown in fig. 2, example 3 is repeated except that the system further comprises a GGH heat exchanger 4. The GGH heat exchanger 4 is arranged between the raw flue gas conveying pipe L0 connected to the flue gas inlet of the first heat transfer zone 401 of the GGH heat exchanger 4 and the SCR reactor 3, the flue gas outlet of the first heat transfer zone 401 of the GGH heat exchanger 4 is connected to the flue gas inlet of the SCR reactor 3 by a sixth pipe L6, both the seventh pipe L7 leading from the flue gas outlet of the main reactor 201 of the CO reactor 2 and the eighth pipe L8 leading from the bypass 202 of the CO reactor 2 are connected to the second heat transfer zone 402 of the GGH heat exchanger 4 via a clean flue gas conveying pipe L9 after merging.
Example 5
Example 4 was repeated except that the raw flue gas duct L0 was provided with a flue gas flow rate detection device 5, a CO concentration detection device 6, and a first temperature detection device 7. The flue gas flow rate detection device 5, the CO concentration detection device 6 and the first temperature detection device 7 are all positioned at the upstream of the connecting position of the fifth pipeline L5 and the original flue gas conveying pipeline L0.
Example 6
Example 5 is repeated, except that the duct near the flue gas inlet of the SCR reactor 3 is provided with a third temperature detection device 9.
Example 7
Example 6 was repeated except that the flue gas outlet of the second heat transfer zone 402 of the GGH heat exchanger 4 was connected to the front end of the combustion-supporting gas conveying pipe L11.
Example 8
As shown in fig. 3, a method for denitration and decarbonization treatment of flue gas comprises the following steps:
1) the first valve k1 is closed, the second valve k2 is opened, and the raw flue gas G is introduced into the raw flue gas conveying pipeline L01；
2) Raw flue gas G1The flue gas enters the SCR reactor 3 for denitration, the denitrated flue gas enters the bypass 202 of the CO reactor 2 through a third pipeline L3, and the flue gas is discharged from a flue gas outlet of the bypass 202 of the CO reactor 2;
3) starting the hot blast stove 1, opening a third valve k3, introducing hot air generated by the hot blast stove 1 into the main reaction tower 201 of the CO reactor 2, and preheating a CO catalyst in the main reaction tower 201;
4) the second temperature detection device 8 monitors the temperature of the CO catalyst in the main reaction tower 201 of the CO reactor 2 in real time; when the temperature of the CO catalyst is detected to reach the set temperature T of the catalyst3When the denitration catalyst is used, the first valve k1 is opened, the second valve k2 is closed, the denitrated flue gas enters the main reaction tower 201 of the CO reactor 2, and contacts with a CO catalyst in the main reaction tower 201 to generate a CO catalytic oxidation reaction; the reaction heat released by the catalytic oxidation of CO heats the flue gas, and the clean flue gas after temperature rise is discharged from the flue gas outlet of the main reaction tower 201 of the CO reactor 2.
Example 9
Example 8 was repeated except that step 1) further included: starting the hot blast stove 1, opening the fourth valve k4, inputting hot blast generated by the hot blast stove 3 into the raw flue gas conveying pipeline L0 through the fifth pipeline L5 in one way, and heating flue gas in the raw flue gas conveying pipeline L0. In the step 2), the heated flue gas enters an SCR reactor 3 for denitration.
Example 10
As shown in fig. 4, a method for denitration and decarbonization treatment of flue gas comprises the following steps:
1) the first valve k1 is closed, the second valve k2 is opened, and the raw flue gas G is introduced into the raw flue gas conveying pipeline L01；
2) Starting the hot blast stove 1, opening a third valve k3 and a fourth valve k4, introducing one path of hot air generated by the hot blast stove 1 into the original flue gas conveying pipeline L0 through a fifth pipeline L5, and heating flue gas in the original flue gas conveying pipeline L0;
3) the heated flue gas enters the SCR reactor 3 for denitration after heat exchange through a first heat exchange zone 401 of the GGH heat exchanger 4, the denitrated flue gas enters a bypass 202 of the CO reactor 2 through a third pipeline L3, and then the flue gas enters a second heat exchange zone 402 of the GGH heat exchanger 4 for heat exchange and is discharged;
4) another path of hot air generated by the hot blast stove 1 is introduced into the main reaction tower 201 of the CO reactor 2 through a fourth pipeline L4, the CO catalyst in the main reaction tower 201 is preheated, and the temperature of the CO catalyst in the main reaction tower 201 of the CO reactor 2 is monitored in real time by the second temperature detection device 8; when the temperature of the CO catalyst is detected to reach the set temperature T of the catalyst3When the denitration catalyst is used, the first valve k1 is opened, the second valve k2 is closed, the denitrated flue gas enters the main reaction tower 201 of the CO reactor 2, and contacts with a CO catalyst in the main reaction tower 201 to generate a CO catalytic oxidation reaction; reaction heat released by CO catalytic oxidation heats flue gas, and the heated clean flue gas enters a second heat exchange area 402 of the GGH heat exchanger 4 for heat exchange and then is discharged.
Example 11
Example 10 was repeated except that in the course of carrying out the method for removing carbon monoxide and denitration from flue gas of the present invention, the raw flue gas G in unit time was measured1Is marked as U1 Nm3H; detecting raw flue gas G1Temperature of (1), denoted as T1DEG C; detecting raw flue gas G1The content of CO in the mixture is marked as P1 g/Nm3。
And (3) calculating: raw gas G in unit time1The mass flow of the medium carbon monoxide is U1*P1g/h; raw gas G in unit time1Heat Q released by combustion of medium carbon monoxide1 kJ/h：
Q1＝a*U1*P1*10.11；
Wherein: a is a combustion coefficient, and the value of a is 0.1-1, preferably 0.4-0.95, and more preferably 0.7-0.9; for example 0.5, 0.6, 0.8, 0.85.
Calculating the original smoke G1After carbon monoxide in the flue gas is converted into carbon dioxide in a main reaction tower 201 of a CO reactor 2, the heat released in the conversion process is used for heating the raw flue gas through a GGH heat exchanger 4, and the nitrate-containing flue gas G before entering an SCR reactor 32Temperature T of2℃：
Figure BDA0002261920640000141
Wherein: c is the average specific heat capacity of the smoke, kJ/(. degree.C.g); b is a heat transfer coefficient, and the value of b is 0.7-1, preferably 0.8-0.98, and more preferably 0.9-0.95; e.g., 0.75, 0.8, 0.85, 0.92; f is a heat exchange coefficient, and the value of f is 0.7-1, preferably 0.8-0.98, and more preferably 0.9-0.95; e.g., 0.75, 0.8, 0.85, 0.92.
Setting the optimum denitration temperature T of the SCR reactor 3 according to the requirement of the SCR reactor 3Denitration℃；
If T2＝TDenitrationThen the raw flue gas G1The carbon monoxide enters a main reaction tower 201 of a CO reactor 2 for catalytic oxidation, and the released heat enables the nitrate-containing flue gas G entering an SCR reactor 32To reach TDenitrationAnd (4) directly carrying out denitration treatment on the flue gas in the SCR reactor 3 at the temperature of DEG C.
If T2＜TDenitrationIncreasing the consumption of the fuel gas and the combustion-supporting gas of the hot blast stove 1 to ensure that the nitrate-containing flue gas G entering the SCR reactor 32To reach TDenitration℃。
If T2＞TDenitrationThe amount of the gas and the combustion-supporting gas of the hot blast stove 1 is adjusted to be small, so that the nitrate-containing flue gas G entering the SCR reactor 32To reach TDenitrationDEG C; if the consumption of the fuel gas and the combustion-supporting gas of the hot blast stove 1 is adjusted to be small until the hot blast stove 1 is shut down, the smoke G containing the saltpeter2Temperature T of2Is still greater than TDenitrationAt this time, the second valve k2 is opened to make part of the raw smoke G1A bypass 202 through the CO reactor 2; the opening degree of the second valve k2 is adjusted so that the nitrate-containing flue gas G entering the SCR reactor 32Down to TDenitration℃。
Example 12
Example 11 is repeated, except that if T2＜TDenitrationThe amount of the fuel gas added to the hot blast stove 1 is as follows:
setting the combustion heat of the gas to N1kJ/g, calculating the mass flow U of the fuel gas to be increased2 Nm3/h：
Figure BDA0002261920640000151
Wherein: e is a combustion coefficient, and the value of the e is 0.6-1, preferably 0.8-0.99, and more preferably 0.8-0.98; for example 0.75, 0.8, 0.85, 0.92, 0.98. That is, the flow rate of the hot blast stove 1 to be supplemented is U in unit time2 Nm3H gas to make the temperature of the flue gas reach T before entering the SCR reactor 3Denitration℃。
Example 13
Example 11 is repeated, except that the saltpeter-containing flue gas G is discharged after the hot-blast stove 1 has been switched off2Temperature T of2Is still greater than TDenitrationIn this case, the adjustment of the second valve k2 is specifically:
calculating the required reduced raw flue gas flow U in the main reactor 201 of the CO reactor 23 Nm3/h：
Figure BDA0002261920640000152
That is, the flow rate of the CO reactor 2 in the main reaction tower 201 needs to be reduced to U per unit time3 Nm3H flue gas; the opening of the second valve k2 is adjusted so that the flue gas flow into the bypass 202 of the CO reactor 2 is U3 Nm3H, thereby allowing entry into the SCR reactionThe temperature of the flue gas before the device 3 is reduced to TDenitration℃。

Claims (15)

1. A flue gas denitration and decarbonization treatment system comprises a hot blast stove (1), a CO reactor (2) and an SCR reactor (3); the CO reactor (2) comprises a main reaction tower (201) and a bypass (202); a raw flue gas conveying pipeline (L0) is connected to a flue gas inlet of the SCR reactor (3), a first pipeline (L1) led out from a flue gas outlet of the SCR reactor (3) is divided into a second pipeline (L2) and a third pipeline (L3), and the second pipeline (L2) and the third pipeline (L3) are respectively connected to a main reaction tower (201) and a bypass (202) of the CO reactor (2); the hot blast outlet of the hot blast stove (1) is connected to the second duct (L2) via a fourth duct (L4).
2. The system of claim 1, wherein: a fifth pipeline (L5) is branched from the fourth pipeline (L4) and is connected to the raw flue gas conveying pipeline (L0).
3. The system according to claim 1 or 2, characterized in that: the system further comprises a first valve (k1) disposed on the second conduit (L2); the first valve (k1) is located upstream of the connection point of the fourth pipeline (L4) and the second pipeline (L2); and/or
The system also includes a second valve (k2) disposed on the third conduit (L3).
4. The system according to any one of claims 1-3, wherein: the system further comprises a GGH heat exchanger (4); the GGH heat exchanger (4) is arranged between a raw flue gas conveying pipeline (L0) and the SCR reactor (3), the raw flue gas conveying pipeline is connected to a flue gas inlet of a first heat exchange area (401) of the GGH heat exchanger (4), a flue gas outlet of the first heat exchange area (401) of the GGH heat exchanger (4) is connected to a flue gas inlet of the SCR reactor (3) through a sixth pipeline (L6), and a seventh pipeline (L7) led out from a flue gas outlet of a main reaction tower (201) of the CO reactor (2) and an eighth pipeline (L8) led out from a bypass (202) of the CO reactor (2) are connected to a second heat exchange area (402) of the GGH heat exchanger (4) through a clean flue gas conveying pipeline (L9) after being combined.
5. The system according to any one of claims 2-4, wherein: a third valve (k3) is arranged on the fourth pipeline (L4); the third valve (k3) is located on the fourth line (L4) downstream of the location where the fifth line (L5) branches off; and/or
The fifth pipeline (L5) is provided with a fourth valve (k 4).
6. The system according to any one of claims 1-5, wherein: the system also comprises a gas conveying pipeline (L10), wherein the gas conveying pipeline (L10) is connected to a gas supplement inlet of the hot blast stove (1); and/or
The system also comprises a combustion gas delivery duct (L11), the combustion gas delivery duct (L11) being connected to a combustion gas make-up inlet of the stove (1).
7. The system according to any one of claims 4-7, wherein: the original flue gas conveying pipeline (L0) is provided with a flue gas flow detection device (5), a CO concentration detection device (6) and a first temperature detection device (7); the smoke flow detection device (5), the CO concentration detection device (6) and the first temperature detection device (7) are all positioned at the upstream of the connecting position of the fifth pipeline (L5) and the original smoke conveying pipeline (L0); and/or
A second temperature detection device (8) is arranged on the side wall of the main reaction tower (201) of the CO reactor (2); and/or
And a third temperature detection device (9) is arranged on the pipeline close to the flue gas inlet of the SCR reactor (3).
8. The system according to claim 6 or 7, characterized in that: the flue gas outlet of the second heat transfer zone (402) of the GGH heat exchanger (4) is connected to the front end of a combustion-supporting gas conveying pipeline (L11).
9. A method for denitration and decarbonization treatment of flue gas or a method for controlling denitration and denitration of flue gas by carbon monoxide by using the system of any one of claims 1 to 8, wherein the method comprises the following steps:
1) the first valve (k1) is closed, the second valve (k2) is opened, and the raw flue gas delivery pipe is openedThe original smoke G is introduced into the flue (L0)1；
2) Raw flue gas G1The flue gas enters an SCR reactor (3) for denitration, the denitrated flue gas enters a bypass (202) of a CO reactor (2) through a third pipeline (L3), and the flue gas is discharged from a flue gas outlet of the bypass (202) of the CO reactor (2);
3) starting the hot blast stove (1), opening a third valve (k3), introducing hot blast generated by the hot blast stove (1) into a main reaction tower (201) of the CO reactor (2), and preheating a CO catalyst in the main reaction tower (201);
4) the second temperature detection device (8) monitors the temperature of the CO catalyst in the main reaction tower (201) of the CO reactor (2) in real time; when the temperature of the CO catalyst is detected to reach the set temperature T of the catalyst3When the denitration catalyst is used, a first valve (k1) is opened, a second valve (k2) is closed, the denitrated flue gas enters a main reaction tower (201) of a CO reactor (2), and contacts with a CO catalyst in the main reaction tower (201) to generate a CO catalytic oxidation reaction; the reaction heat released by CO catalytic oxidation heats the flue gas, and the clean flue gas after temperature rise is discharged from a flue gas outlet of a main reaction tower (201) of the CO reactor (2).
10. The method of claim 9, wherein: the step 1) also comprises the following steps: starting the hot blast stove (1), opening a fourth valve (k4), inputting hot blast generated by the hot blast stove (3) into a raw flue gas conveying pipeline (L0) through a fifth pipeline (L5) in one way, and heating flue gas in the raw flue gas conveying pipeline (L0); in the step 2), the heated flue gas enters an SCR reactor (3) for denitration.
11. A method for flue gas carbon monoxide removal denitration or a method for controlling flue gas carbon monoxide removal denitration by using the system of any one of claims 1 to 8, the method comprising the following steps:
1) the first valve (k1) is closed, the second valve (k2) is opened, and the raw flue gas G is introduced into the raw flue gas conveying pipeline (L0)1；
2) Starting the hot blast stove (1), opening a third valve (k3) and a fourth valve (k4), introducing one path of hot air generated by the hot blast stove (1) into the raw flue gas conveying pipeline (L0) through a fifth pipeline (L5), and heating flue gas in the raw flue gas conveying pipeline (L0);
3) the heated flue gas enters an SCR reactor (3) for denitration after heat exchange through a first heat exchange area (401) of a GGH heat exchanger (4), the denitrated flue gas enters a bypass (202) of a CO reactor (2) through a third pipeline (L3), and then the flue gas enters a second heat exchange area (402) of the GGH heat exchanger (4) for heat exchange and is discharged;
4) the other path of hot air generated by the hot blast stove (1) is introduced into a main reaction tower (201) of the CO reactor (2) through a fourth pipeline (L4) to preheat a CO catalyst in the main reaction tower (201), and a second temperature detection device (8) monitors the temperature of the CO catalyst in the main reaction tower (201) of the CO reactor (2) in real time; when the temperature of the CO catalyst is detected to reach the set temperature T of the catalyst3When the denitration catalyst is used, a first valve (k1) is opened, a second valve (k2) is closed, the denitrated flue gas enters a main reaction tower (201) of a CO reactor (2), and contacts with a CO catalyst in the main reaction tower (201) to generate a CO catalytic oxidation reaction; reaction heat released by CO catalytic oxidation heats flue gas, and the heated clean flue gas enters a second heat exchange area (402) of the GGH heat exchanger (4) for heat exchange and then is discharged.
12. The method of claim 11, wherein: detecting raw flue gas G in unit time1Is marked as U1 Nm3H; detecting raw flue gas G1Temperature of (1), denoted as T1DEG C; detecting raw flue gas G1The content of CO in the mixture is marked as P1 g/Nm3(ii) a And (3) calculating: raw gas G in unit time1The mass flow of the medium carbon monoxide is U1*P1g/h; raw gas G in unit time1Heat Q released by combustion of medium carbon monoxide1 kJ/h：
Q1＝a*U1*P1*10.11；
Wherein: a is a combustion coefficient, and the value of a is 0.1-1, preferably 0.4-0.95, and more preferably 0.7-0.9;
calculating the original smoke G1After carbon monoxide in the CO reactor (2) is converted into carbon dioxide in a main reaction tower (201), the heat released in the conversion process is used for heating raw flue gas through a GGH heat exchanger (4) and then enters a SCR reactor (3)Flue gas G containing nitrate2Temperature T of2℃：
Figure FDA0002261920630000031
Wherein: c is the average specific heat capacity of the smoke, kJ/(. degree.C.g); b is a heat transfer coefficient, and the value of b is 0.7-1, preferably 0.8-0.98, and more preferably 0.9-0.95; f is a heat exchange coefficient, and the value of f is 0.7-1, preferably 0.8-0.98, and more preferably 0.9-0.95.
13. The method of claim 12, wherein: setting the optimal denitration temperature of the SCR reactor (3) as T according to the requirement of the SCR reactor (3)Denitration℃；
If T2＝TDenitrationThen the raw flue gas G1The carbon monoxide enters a main reaction tower (201) of a CO reactor (2) for catalytic oxidation, and the released heat enables nitrate-containing flue gas G entering an SCR reactor (3)2To reach TDenitrationThe flue gas is directly subjected to denitration treatment in an SCR reactor (3);
if T2＜TDenitrationIncreasing the consumption of fuel gas and combustion-supporting gas of the hot blast stove (1) to ensure that the nitrate-containing flue gas G entering the SCR reactor (3)2To reach TDenitration℃；
If T2＞TDenitrationThe amount of the fuel gas and the combustion-supporting gas of the hot blast stove (1) is adjusted to ensure that the nitrate-containing flue gas G entering the SCR reactor (3)2To reach TDenitrationDEG C; if the consumption of the fuel gas and the combustion-supporting gas of the hot blast stove (1) is adjusted to be small until the hot blast stove (1) is shut down, the smoke G containing the saltpeter2Temperature T of2Is still greater than TDenitrationAt this time, the second valve (k2) is opened to make part of the original smoke G1A bypass (202) flowing through the CO reactor (2); the opening degree of the second valve (k2) is adjusted, so that the nitrate-containing flue gas G entering the SCR reactor (3)2Down to TDenitration℃。
14. The method of claim 13, wherein: if T2＜TDenitrationThe amount of the fuel gas added to the hot blast stove (1) is as follows:
setting the combustion heat of the gas to N1kJ/g, calculating the mass flow U of the fuel gas to be increased2 Nm3/h：
Figure FDA0002261920630000041
Wherein: e is a combustion coefficient, and the value of the e is 0.6-1, preferably 0.8-0.99, and more preferably 0.8-0.98; that is to say, the flow rate needed to be supplemented in the hot blast stove (1) is U in unit time2 Nm3H gas to make the temperature of the flue gas reach T before entering the SCR reactor (3)Denitration℃。
15. The method according to claim 13 or 14, characterized in that: if the hot blast stove (1) is shut down, the smoke G containing the saltpeter2Temperature T of2Is still greater than TDenitrationThe regulation of the second valve (k2) is now specifically:
calculating the flow U of the primary flue gas to be reduced in the main reactor (201) of a CO reactor (2)3 Nm3/h：
Figure FDA0002261920630000042
That is, the flow rate of the CO reactor (2) in the main reaction tower (201) needs to be reduced to U per unit time3 Nm3H flue gas; the opening degree of the second valve (k2) is adjusted so that the flow rate of flue gas entering a bypass (202) of the CO reactor (2) is U3 Nm3H, so that the temperature of the flue gas is reduced to T before entering the SCR reactor (3)Denitration℃。
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