CN112403222A - CO oxidation and denitration system and method - Google Patents

CO oxidation and denitration system and method Download PDF

Info

Publication number
CN112403222A
CN112403222A CN201911074331.9A CN201911074331A CN112403222A CN 112403222 A CN112403222 A CN 112403222A CN 201911074331 A CN201911074331 A CN 201911074331A CN 112403222 A CN112403222 A CN 112403222A
Authority
CN
China
Prior art keywords
flue gas
denitration
pipeline
oxidation
temperature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN201911074331.9A
Other languages
Chinese (zh)
Other versions
CN112403222B (en
Inventor
叶恒棣
魏进超
康建刚
刘昌齐
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zhongye Changtian International Engineering Co Ltd
Original Assignee
Zhongye Changtian International Engineering Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zhongye Changtian International Engineering Co Ltd filed Critical Zhongye Changtian International Engineering Co Ltd
Priority to CN201911074331.9A priority Critical patent/CN112403222B/en
Publication of CN112403222A publication Critical patent/CN112403222A/en
Application granted granted Critical
Publication of CN112403222B publication Critical patent/CN112403222B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • B01D53/62—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
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • 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
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8631—Processes characterised by a specific device
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2256/00—Main component in the product gas stream after treatment
    • B01D2256/22—Carbon dioxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/40—Nitrogen compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/50—Carbon oxides
    • B01D2257/502—Carbon monoxide
    • 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
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

A CO oxidation and denitration system comprises an SCR reactor (1) and a CO oxidation device (2); the CO oxidation device (2) is a gas-solid indirect heat exchange tower with a shell-and-tube structure, wherein the inner layer is a main reaction tower (201) of the CO oxidation device (2), and the outer layer is a preheating chamber (202) of the CO oxidation device (2); the raw flue gas conveying pipeline (L0) is connected to a flue gas inlet of the SCR reactor (1), a first pipeline (L1) led out from a flue gas outlet of the SCR reactor (1) 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 preheating chamber (202) of the CO oxidation device (2). 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

CO oxidation and denitration system and method
Technical Field
The invention relates to a treatment system and a treatment method for removing carbon monoxide and denitration from flue gas, in particular to a system and a method for CO oxidation and denitration, belonging 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 oxidation device adopts a shell-and-tube structure, and the denitrated flue gas or the denitrated flue gas heated by the hot blast stove is used for indirectly heating the CO catalyst in the main reaction tower of the CO oxidation device 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 the flue gas during the 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 present invention, a system for the coordinated denitration of a CO oxidation plant is provided.
A CO oxidation and denitration system comprises an SCR reactor and a CO oxidation device. The CO oxidation device is a gas-solid indirect heat exchange tower with a shell-and-tube structure, wherein the inner layer is a main reaction tower of the CO oxidation device, and the outer layer is a preheating chamber of the CO oxidation device. 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 separated 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 of the CO oxidation device and a preheating chamber.
In the present invention, the system further comprises a hot blast stove. The hot air outlet of the hot blast stove is connected to the first 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.
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 oxidation device and an eighth pipeline led out from a preheating chamber of the CO oxidation device are connected to a second heat exchange area of the GGH heat exchanger through a clean flue gas conveying pipeline after being combined.
In the invention, a CO catalyst module is arranged in a main reaction tower of the CO oxidation device. Preferably, the number of CO catalyst modules is from 1 to 10, preferably from 2 to 8, more preferably from 3 to 6.
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 detecting device is provided on a side wall of the main reaction tower of the CO oxidation apparatus.
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.
According to a second embodiment of the present invention, a CO oxidation coupled denitration method is provided.
A CO oxidation-denitration method or a method for controlling CO oxidation-denitration 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 G1The flue gas enters an SCR reactor for denitration, the denitrated flue gas enters a preheating chamber of a CO oxidation device through a third pipeline, a CO catalyst module in a main reaction tower of the CO oxidation device is indirectly heated, and the flue gas heated by the CO catalyst module is discharged from a flue gas outlet of the preheating chamber of the CO oxidation device;
3) the second temperature detection device monitors the temperature of a CO catalyst module in a main reaction tower of the CO oxidation device in real time; when the temperature of the CO catalyst module is detected to reach the set catalyst temperature T3When 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 oxidation device, 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 oxidation device.
Preferably, step 2) further comprises: and starting the hot blast stove, opening the third valve, inputting hot air generated by the hot blast stove into the first pipeline through the fourth pipeline, and heating the denitrated flue gas in the first pipeline.
Preferably, step 1) further comprises: starting the hot blast stove, opening the fourth valve, inputting hot blast generated by the hot blast stove into the original flue gas conveying pipeline through a fifth pipeline in one way, and heating 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 present invention, a CO oxidation coupled denitration method is provided.
A CO oxidation-denitration method or a method for controlling CO oxidation-denitration 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 G1The flue gas after denitration enters a preheating chamber of a CO oxidation device through a third pipeline, a CO catalyst module in a main reaction tower of the CO oxidation device is indirectly heated, and the flue gas after heating of the CO catalyst module is discharged from a flue gas outlet of the preheating chamber of the CO oxidation device;
3) the second temperature detection device monitors the temperature of a CO catalyst module in a main reaction tower of the CO oxidation device in real time; when the temperature of the CO catalyst module is detected to reach the set catalyst temperature T3When 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 oxidation device, 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, step 2) further comprises: and starting the hot blast stove, opening the third valve, inputting hot air generated by the hot blast stove into the first pipeline through the fourth pipeline, and heating the denitrated flue gas in the first pipeline.
Preferably, step 1) further comprises: starting the hot blast stove, opening the fourth valve, inputting hot blast generated by the hot blast stove into the original flue gas conveying pipeline through a fifth pipeline in one way, and heating 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.
Preferably, in the process of implementing the CO oxidation and denitration method, the raw flue gas G is detected1Temperature of (1), denoted as T1DEG C; the set temperature of the CO catalyst is T3DEG C; if T1≥T3If so, the system continues to operate;
if T1＜T3Then starting the hot blast stove to process the raw flue gas G1And/or heating the denitrated flue gas; when the second temperature detection device detects that the inside of the main reaction tower isTemperature of the CO catalyst module up to T3And if so, shutting down the hot blast stove and continuing to operate the system.
Preferably, the raw flue gas G per unit time is detected1Is marked as U1Nm3H; 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 P1g/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 monoxide1kJ/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 oxidation device is converted into carbon dioxide in a main reaction tower, the heat released in the conversion process is used for heating the raw flue gas through a GGH heat exchanger, and the nitrate-containing flue gas G enters an SCR reactor2Temperature T of2℃：
Figure BDA0002261922850000051
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.
Setting the optimal denitration temperature of the SCR reactor to be T according to the requirements of the SCR reactorDenitration℃。
The following analyses were performed:
if T2＝TDenitrationThen the raw flue gas G1The carbon monoxide enters a main reaction tower of a CO oxidation device for catalytic oxidation, and the released heat enables the nitrate-containing flue gas G entering an SCR reactor2To reach TDenitrationThe flue gas is directly denitrated in an SCR reactor at the temperature of DEG CAnd (6) processing.
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 G1Flowing through a pre-heating chamber of a CO oxidation device; 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 flow U of the fuel gas to be increased2Nm3/h：
Figure BDA0002261922850000052
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 U2Nm3H 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 oxidation plant3Nm3/h：
Figure BDA0002261922850000061
That is to say a unit of timeIn the main reaction tower of CO oxidation device, the flow rate is required to be reduced to U3Nm3H flue gas; the opening degree of the second valve is adjusted to ensure that the flow rate of the flue gas entering the preheating chamber of the CO oxidation device 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 oxidation device 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 oxidation device 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, the carbon monoxide is an exothermic reaction, the carbon monoxide in the flue gas is converted into carbon dioxide through a CO oxidation device, and the heat released by the reaction is used for heating 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 invention designs the traditional CO treatment device into a tube-shell type gas-solid indirect heat exchange tower, which comprises a main reaction tower at the inner layer and a preheating chamber at the outer layer, 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 oxidation device (namely a CO treatment device) but enters a preheating chamber of the CO oxidation device, and then is discharged. In the process of flowing through the preheating chamber, the flue gas in the preheating chamber can indirectly heat the 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 oxidation device 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.
The invention is also provided with a hot blast stove. When the temperature (or heat) of the flue gas is not enough to raise the temperature of the CO catalyst to the set temperature T of the CO catalyst3When the denitration device is used, the hot blast stove is started, the hot blast first pipeline generated by the hot blast stove heats the denitrated flue gas in the first pipeline, and the heated flue gas enters the preheating chamber of the CO oxidation device to preheat the CO catalyst in the main reaction tower of the CO oxidation device, so that the temperature of the CO catalyst reaches the set temperature T of the CO catalyst3. 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. 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 takes the temperature of the raw flue gas into consideration of not high, 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 the denitration efficiency. And the temperature of the raw flue gas is increased, so that the flue gas is further ensured to enter the CO oxidation device, 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 CO oxidation and denitration system comprises an SCR reactor and a CO oxidation device. The raw flue gas firstly enters an SCR reactor for denitration, and the denitrated flue gas enters a CO oxidation device 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. And when the flue gas after denitration flows through the CO oxidation device, CO in the flue gas is oxidized into carbon dioxide to release heat, the emitted heat heats the flue gas, then the 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 denitration by an SCR method, and then the flue gas enters the SCR reactor to be subjected to denitration treatment. The CO oxidation device is a gas-solid indirect heat exchange tower with a shell-and-tube structure, the CO oxidation device comprises an internal main reaction tower and an external preheating chamber, a CO catalyst module is arranged in the main reaction tower, and when smoke flows through the external preheating chamber, the smoke can indirectly heat the CO catalyst module in the main reaction tower. The invention also comprises a hot blast stove which supplies energy for the CO oxidation device. In addition, the number of the CO catalyst modules in the CO oxidation device can be one or more, and when the number of the CO catalyst modules is more than one, the heat exchange area can be increased, and the heat exchange effect is enhanced.
In the method, at the beginning of system startup, when the CO catalyst in the main reaction tower of the CO oxidation device is in a low-temperature state and the temperature of the raw flue gas can reach the set temperature of the CO catalyst (ensuring that the CO catalyst is not inactivated), the first valve is closed, the second valve is opened, the raw flue gas enters the SCR reactor for denitration and then flows through the preheating chamber outside the CO oxidation device, and the raw flue gas indirectly heats the CO catalyst module in the main reaction tower inside the CO oxidation device. When the temperature of the CO catalyst module in the main reaction tower reaches the set temperature T of the catalyst3(the second temperature detection device monitors the temperature of the CO catalyst in real time), the first valve is opened, the second valve is closed, the denitrated flue gas enters the main reaction tower of the CO oxidation device, and contacts with the CO catalyst to generate a CO catalytic oxidation reaction, the heat emitted by the reaction heats the flue gas, and the heated clean flue gas is discharged from the flue gas outlet of the main reaction tower 201 of the CO oxidation device 2.
The temperature of the original smoke is detected by a first temperature detection device, and the temperature T of the original smoke is detected1Less than the set temperature T of the CO catalyst3And when the temperature of the raw flue gas is not enough to heat the CO catalyst module in the main reaction tower to the set temperature, the hot blast stove needs to be started. Hot-blast stoveThe generated hot air heats the original flue gas, and the heated flue gas enters the preheating chamber to indirectly heat the CO catalyst module in the main reaction tower, so that the CO catalyst can reach a set temperature, and the CO catalyst is prevented from being poisoned and losing efficacy.
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 BDA0002261922850000081
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 heat released by carbon monoxide converted into carbon dioxide is hardly absorbed by the original flue gas, and can be obtained according to engineering experience, and the value is 0.7-1, preferably 0.8-0.98, and 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, by utilizing the heat released by the conversion of carbon monoxide in the flue gas, it is just possible to make the flue gas enter the SCRNitrate-containing flue gas G of reactor2To 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 calculation2Nm3H gas:
Figure BDA0002261922850000091
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 combustion of the hot-blast stove is adjusted smallThe gas and the combustion-supporting gas are used until the hot blast stove is shut down and the smoke G containing the nitrate2Temperature T of2Is still greater than TDenitrationAt the moment, the second valve is opened to lead part of the original smoke G1Flows through a preheating chamber of a CO oxidation device, so that 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 oxidation plant3Nm3/h：
Figure BDA0002261922850000092
That is, the flow rate of the main reaction tower of the CO oxidation device needs to be reduced to U in unit time3Nm3H flue gas; the opening degree of the second valve is adjusted to ensure that the flow rate of the flue gas entering the preheating chamber of the CO oxidation device 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 oxidation device adopts a shell-and-tube structure, and the CO catalyst in the main reaction tower of the CO oxidation device is indirectly heated by using the flue gas or the flue gas heated by the hot blast stove at the beginning of the system starting, so that the problem that the CO catalyst is easy to be poisoned and lose efficacy when encountering sulfur oxides in the flue gas during the cold starting of the system is avoided;
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 CO oxidation and denitration system according to the present invention;
FIG. 2 is a schematic structural diagram of a CO oxidation and denitration system provided with a GGH heat exchanger;
FIG. 3 is a schematic structural diagram of a CO oxidation and denitration system provided with a plurality of CO catalyst modules according to the present invention;
FIG. 4 is a process flow diagram of a CO oxidation-CO-denitration method of the present invention;
FIG. 5 is a process flow diagram of another CO oxidation-CO-denitration method of the present invention.
Reference numerals:
1: an SCR reactor; 2: a CO oxidation unit; 201: a main reaction tower of a CO oxidation device; 20101: a CO catalyst module; 202: a preheating chamber of the CO oxidation device; 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 CO oxidation and denitration system comprises an SCR reactor 1 and a CO oxidation device 2. The CO oxidation device 2 is a gas-solid indirect heat exchange tower with a shell-and-tube structure, wherein the inner layer is a main reaction tower 201 of the CO oxidation device 2, and the outer layer is a preheating chamber 202 of the CO oxidation device 2. The raw flue gas conveying pipeline L0 is connected to the flue gas inlet of the SCR reactor 1, 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 1, and the second pipeline L2 and the third pipeline L3 are respectively connected to the main reaction tower 201 and the preheating chamber 202 of the CO oxidation device 2.
In the present invention, the system further comprises a hot blast stove 3. The hot blast outlet of the hot blast stove 3 is connected to the first conduit L1 via a fourth conduit 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.
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 1, 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 1 through a sixth pipe L6, both the seventh pipe L7 leading from the flue gas outlet of the main reaction tower 201 of the CO oxidation device 2 and the eighth pipe L8 leading from the preheating chamber 202 of the CO oxidation device 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 being merged.
In the present invention, a CO catalyst module 20101 is provided in the main reaction tower 201 of the CO oxidation apparatus 2. Preferably, the number of CO catalyst modules 20101 is from 1 to 10, preferably from 2 to 8, more preferably from 3 to 6.
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 3.
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 3.
Preferably, the raw flue gas duct 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 oxidation device 2.
Preferably, a third temperature detection device 9 is arranged on the pipeline close to the flue gas inlet of the SCR reactor 1.
Example 1
As shown in fig. 1, the CO oxidation and denitration system comprises an SCR reactor 1 and a CO oxidation device 2. The CO oxidation device 2 is a gas-solid indirect heat exchange tower with a shell-and-tube structure, wherein the inner layer is a main reaction tower 201 of the CO oxidation device 2, and the outer layer is a preheating chamber 202 of the CO oxidation device 2. A CO catalyst module 20101 is provided in the main reaction tower 201 of the CO oxidation apparatus 2. The raw flue gas conveying pipeline L0 is connected to the flue gas inlet of the SCR reactor 1, 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 1, and the second pipeline L2 and the third pipeline L3 are respectively connected to the main reaction tower 201 and the preheating chamber 202 of the CO oxidation device 2. The side wall of the main reaction tower 201 of the CO oxidation device 2 is provided with a second temperature detection device 8.
Example 2
Example 1 is repeated except that the system further comprises a hot blast stove 3. The hot blast outlet of the hot blast stove 3 is connected to the first conduit L1 via a fourth conduit L4. The system further comprises a gas delivery duct L10, the gas delivery duct L10 being connected to a gas supplementary inlet of the stove 3. 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 3.
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
Example 3 is repeated except that the system further includes a first valve k1 provided on the second pipe L2. The system further includes a second valve k2 provided on the third pipe L3.
Example 5
As shown in fig. 2, example 4 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 1, 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 1 through a sixth pipe L6, both the seventh pipe L7 leading from the flue gas outlet of the main reaction tower 201 of the CO oxidation device 2 and the eighth pipe L8 leading from the preheating chamber 202 of the CO oxidation device 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 being merged.
Example 6
As shown in fig. 3, example 5 was repeated except that the number of CO catalyst modules 20101 in the main reaction tower 201 of the CO oxidation apparatus 2 was 2.
Example 7
Example 5 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 8
Example 7 is repeated, except that the duct near the flue gas inlet of the SCR reactor 1 is provided with a third temperature detection device 9.
Example 9
As shown in fig. 4, a CO oxidation-CO-denitration method includes 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 1 for denitration, the denitrated flue gas enters the preheating chamber 202 of the CO oxidation device 2 through a third pipeline L3, the CO catalyst module 20101 in the main reaction tower 201 of the CO oxidation device 2 is indirectly heated, and the flue gas heated by the CO catalyst module 20101 is discharged from a flue gas outlet of the preheating chamber 202 of the CO oxidation device 2;
3) the second temperature detection device 8 monitors the temperature of the CO catalyst module 20101 in the main reaction tower 201 of the CO oxidation device 2 in real time; when the temperature of the CO catalyst module 20101 is detected to reach the set catalyst temperature T3When the denitration flue gas enters the main reaction tower 201 of the CO oxidation device 2, the denitration flue gas contacts with a CO catalyst in the main reaction tower 201 to generate a CO catalytic oxidation reaction by opening the first valve k1 and closing the second valve k 2; 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 oxidation device 2.
Example 10
Example 9 was repeated except that step 2) further included: and starting the hot blast stove 3, opening a third valve k3, inputting hot air generated by the hot blast stove 3 into the first pipeline L1 through the fourth pipeline L4, and heating the denitrated flue gas in the first pipeline L1.
Example 11
Example 10 was repeated except that step 1) further included: starting the hot blast stove 3, opening a fourth valve k4, inputting hot blast generated by the hot blast stove 3 into the 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 1 for denitration.
Example 12
As shown in fig. 5, a CO oxidation-CO-denitration method includes 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 1 for denitration after heat exchange through the first heat exchange zone 401 of the GGH heat exchanger 4, the denitrated flue gas enters the preheating chamber 202 of the CO oxidation device 2 through the third pipeline L3, the CO catalyst module 20101 in the main reaction tower 201 of the CO oxidation device 2 is indirectly heated, and the flue gas heated by the CO catalyst module 20101 is discharged from a flue gas outlet of the preheating chamber 202 of the CO oxidation device 2;
3) the second temperature detection device 8 monitors the temperature of the CO catalyst module 20101 in the main reaction tower 201 of the CO oxidation device 2 in real time; when the temperature of the CO catalyst module 20101 is detected to reach the set catalyst temperature T3When the denitration flue gas enters the main reaction tower 201 of the CO oxidation device 2, the denitration flue gas contacts with a CO catalyst in the main reaction tower 201 to generate a CO catalytic oxidation reaction by opening the first valve k1 and closing the second valve k 2; 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 13
Example 12 is repeated except that step 2) further comprises: and starting the hot blast stove 3, opening a third valve k3, inputting hot air generated by the hot blast stove 3 into the first pipeline L1 through the fourth pipeline L4, and heating the denitrated flue gas in the first pipeline L1.
Example 14
Example 13 was repeated except that step 1) further included: starting the hot blast stove 3, opening a fourth valve k4, inputting hot blast generated by the hot blast stove 3 into the 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 1 for denitration.
Example 15
Example 13 or 14 was repeated except that in the CO oxidation-denitration method of the present invention, the raw flue gas G was detected1Temperature of (1), denoted as T1DEG C; the set temperature of the CO catalyst is T3℃；
If T1≥T3If so, the system continues to operate;
if T1＜T3Then the hot blast stove 3 is started to carry out the treatment of the original smoke G1And/or heating the denitrated flue gas; when the second temperature detection device 8 detects that the temperature of the CO catalyst module 20101 in the main reaction tower 201 reaches T3And if so, the hot blast stove 3 is shut down, and the system continues to operate.
Example 16
Example 15 was repeated except that in the process of performing the CO oxidation-denitration method of the present invention, the raw flue gas G per unit time was measured1Is marked as U1Nm3H; 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 P1g/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 monoxide1kJ/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 CO oxidation device 2 is converted into carbon dioxide in the main reaction tower 201, the heat released in the conversion process is used for heating the raw flue gas through the GGH heat exchanger 4, and the raw flue gas enters the nitrate-containing flue gas G of the SCR reactor 12Temperature T of2℃：
Figure BDA0002261922850000151
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.
The maximum value of the SCR reactor 1 is set according to the requirements of the SCR reactor 1The optimum denitration temperature is TDenitration℃；
If T2＝TDenitrationThen the raw flue gas G1The carbon monoxide enters a main reaction tower 201 of a CO oxidation device 2 for catalytic oxidation, and the released heat enables the nitrate-containing flue gas G entering an SCR reactor 12To reach TDenitrationAnd (4) directly carrying out denitration treatment on the flue gas in the SCR reactor 1 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 3 to ensure that the nitrate-containing flue gas G entering the SCR reactor 12To reach TDenitration℃。
If T2＞TDenitrationThe amount of the gas and the combustion-supporting gas of the hot blast stove 3 is adjusted to be small, so that the nitrate-containing flue gas G entering the SCR reactor 12To reach TDenitrationDEG C; if the amount of the fuel gas and the combustion-supporting gas of the hot blast stove 3 is adjusted to be small until the hot blast stove 3 is shut down, the smoke G containing the nitrate2Temperature T of2Is still greater than TDenitrationAt this time, the second valve k2 is opened to make part of the raw smoke G1Flows through the preheating chamber 202 of the CO oxidation device 2; the opening degree of the second valve k2 is adjusted so that the nitrate-containing flue gas G entering the SCR reactor 12Down to TDenitration℃。
Example 17
Example 16 is repeated, except that if T2＜TDenitrationAnd the amount of the fuel gas of the hot blast stove 3 is increased as follows:
setting the combustion heat of the gas to N1kJ/g, calculating the flow U of the fuel gas to be increased2Nm3/h：
Figure BDA0002261922850000152
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 3 to be supplemented is U in unit time2Nm3H gas to make the temperature of the flue gas reach T before entering the SCR reactor 1Denitration℃。
Example 18
Example 16 is repeated, except that the nitrate-containing flue gas G is discharged after the hot-blast stove 3 has been switched off2Temperature T of2Is still greater than TDenitrationIn this case, the adjustment of the second valve k2 is specifically:
calculating the flow U of the raw flue gas to be reduced in the main reactor 201 of the CO oxidation plant 23Nm3/h：
Figure BDA0002261922850000161
That is, the flow rate of the CO oxidation apparatus 2 in the main reaction tower 201 needs to be reduced to U per unit time3Nm3H flue gas; the opening degree of the second valve k2 is adjusted so that the flow rate of flue gas entering the preheating chamber 202 of the CO oxidation device 2 is U3Nm3H, so that the temperature of the flue gas is reduced to T before entering the SCR reactor 1Denitration℃。

Claims (17)

1. A CO oxidation and denitration system comprises an SCR reactor (1) and a CO oxidation device (2); the CO oxidation device (2) is a gas-solid indirect heat exchange tower with a shell-and-tube structure, wherein the inner layer is a main reaction tower (201) of the CO oxidation device (2), and the outer layer is a preheating chamber (202) of the CO oxidation device (2); the raw flue gas conveying pipeline (L0) is connected to a flue gas inlet of the SCR reactor (1), a first pipeline (L1) led out from a flue gas outlet of the SCR reactor (1) 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 preheating chamber (202) of the CO oxidation device (2).
2. A system according to claim 1, characterized in that: the system also comprises a hot blast stove (3); the hot air outlet of the hot blast stove (3) is connected to the first conduit (L1) via a fourth conduit (L4);
preferably, a fifth pipeline (L5) branching from the fourth pipeline (L4) 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); 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 (1), 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 (1) 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 oxidation device (2) and an eighth pipeline (L8) led out from a preheating chamber (202) of the CO oxidation device (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 1-4, wherein: a CO catalyst module (20101) is arranged in a main reaction tower (201) of the CO oxidation device (2); preferably, the number of CO catalyst modules (20101) is from 1 to 10, preferably from 2 to 8, more preferably from 3 to 6.
6. The system according to any one of claims 2-5, 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).
7. The system according to any one of claims 2-6, wherein: the system also comprises a gas delivery duct (L10), the gas delivery duct (L10) being connected to a gas supplementary inlet of the stove (3); 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 hot blast stove (3).
8. 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 oxidation device (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 (1).
9. A method of CO oxidation coupled denitration or a method of controlling CO oxidation coupled denitration using the system of any one of claims 1 to 8, the method comprising the steps of:
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) Raw flue gas G1The flue gas enters an SCR reactor (1) for denitration, the denitrated flue gas enters a preheating chamber (202) of a CO oxidation device (2) through a third pipeline (L3), a CO catalyst module (20101) in a main reaction tower (201) of the CO oxidation device (2) is indirectly heated, and the flue gas heated by the CO catalyst module (20101) is discharged from a flue gas outlet of the preheating chamber (202) of the CO oxidation device (2);
3) the second temperature detection device (8) monitors the temperature of a CO catalyst module (20101) in a main reaction tower (201) of the CO oxidation device (2) in real time; when the temperature of the CO catalyst module (20101) is detected to reach the set catalyst temperature T3When the denitration flue gas enters the main reaction tower (201) of the CO oxidation device (2), the denitration flue gas contacts with a CO catalyst in the main reaction tower (201) to generate a CO catalytic oxidation reaction by opening the first valve (k1) and closing the second valve (k 2); 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 oxidation device (2).
10. The method of claim 9, wherein: the step 2) also comprises the following steps: starting the hot blast stove (3), opening a third valve (k3), inputting hot air generated by the hot blast stove (3) into a first pipeline (L1) through a fourth pipeline (L4), and heating the denitrated flue gas in the first pipeline (L1).
Preferably, step 1) further comprises: starting the hot blast stove (3), opening a fourth valve (k4), inputting hot blast generated by the hot blast stove (3) into the original flue gas conveying pipeline (L0) through a fifth pipeline (L5) in one way, and heating flue gas in the original flue gas conveying pipeline (L0); in the step 2), the heated flue gas enters the SCR reactor (1) for denitration.
11. A method of CO oxidation coupled denitration or a method of controlling CO oxidation coupled denitration using the system of any one of claims 1 to 8, the method comprising the steps of:
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) Raw flue gas G1The flue gas enters an SCR reactor (1) for denitration after heat exchange through a first heat exchange zone (401) of a GGH heat exchanger (4), the flue gas after denitration enters a preheating chamber (202) of a CO oxidation device (2) through a third pipeline (L3), a CO catalyst module (20101) in a main reaction tower (201) of the CO oxidation device (2) is indirectly heated, and the flue gas after heating of the CO catalyst module (20101) is discharged from a flue gas outlet of the preheating chamber (202) of the CO oxidation device (2);
3) the second temperature detection device (8) monitors the temperature of a CO catalyst module (20101) in a main reaction tower (201) of the CO oxidation device (2) in real time; when the temperature of the CO catalyst module (20101) is detected to reach the set catalyst temperature T3When the denitration flue gas enters the main reaction tower (201) of the CO oxidation device (2), the denitration flue gas contacts with a CO catalyst in the main reaction tower (201) to generate a CO catalytic oxidation reaction by opening the first valve (k1) and closing the second valve (k 2); 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: the step 2) also comprises the following steps: starting the hot blast stove (3), opening a third valve (k3), inputting hot air generated by the hot blast stove (3) into a first pipeline (L1) through a fourth pipeline (L4), and heating the denitrated flue gas in the first pipeline (L1).
Preferably, step 1) further comprises: starting the hot blast stove (3), opening a fourth valve (k4), inputting hot blast generated by the hot blast stove (3) into the original flue gas conveying pipeline (L0) through a fifth pipeline (L5) in one way, and heating flue gas in the original flue gas conveying pipeline (L0); in the step 2), the heated flue gas enters the SCR reactor (1) for denitration.
13. The method of claim 12, wherein: detecting raw flue gas G1Temperature of (1), denoted as T1DEG C; the set temperature of the CO catalyst is T3DEG C; if T1≥T3If so, the system continues to operate;
if T1＜T3Then the hot blast stove (3) is started to carry out the treatment of the raw flue gas G1And/or heating the denitrated flue gas; when the second temperature detection device (8) detects that the temperature of the CO catalyst module (20101) in the main reaction tower (201) reaches T3And in the meantime, the hot blast stove (3) is shut down, and the system continues to operate.
14. The method of claim 13, 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 flue gas is converted into carbon dioxide in a main reaction tower (201) of a CO oxidation device (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 (1)2Temperature T of2℃：
Figure FDA0002261922840000041
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.
15. The method of claim 14, wherein: setting the optimal denitration temperature of the SCR reactor (1) as T according to the requirement of the SCR reactor (1)Denitration℃；
If T2＝TDenitrationThen the raw flue gas G1The carbon monoxide enters a main reaction tower (201) of a CO oxidation device (2) for catalytic oxidation, and the released heat enables the nitrate-containing flue gas G entering an SCR reactor (1)2To reach TDenitrationThe flue gas is directly subjected to denitration treatment in an SCR reactor (1);
if T2＜TDenitrationThe consumption of the fuel gas and the combustion-supporting gas of the hot blast stove (3) is increased, so that the nitrate-containing flue gas G entering the SCR reactor (1)2To reach TDenitration℃；
If T2＞TDenitrationThe amount of the fuel gas and the combustion-supporting gas of the hot blast stove (3) is adjusted to ensure that the nitrate-containing flue gas G entering the SCR reactor (1)2To reach TDenitrationDEG C; if the consumption of the fuel gas and the combustion-supporting gas of the hot blast stove (3) is adjusted to be less than the consumption of the combustion-supporting gas after the hot blast stove (3) 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 G1Flows through a preheating chamber (202) of the CO oxidation device (2); regulating deviceThe opening degree of the second valve (k2) is adjusted, so that the nitrate-containing flue gas G entering the SCR reactor (1)2Down to TDenitration℃。
16. The method of claim 15, wherein: if T2＜TDenitrationThe amount of the fuel gas added to the hot blast stove (3) is as follows:
setting the combustion heat of the gas to N1kJ/g, calculating the flow U of the fuel gas to be increased2Nm3/h：
Figure FDA0002261922840000042
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 (3) is U in unit time2 Nm3H gas to make the temperature of the flue gas reach T before entering the SCR reactor (1)Denitration℃。
17. The method according to claim 15 or 16, characterized in that: if the hot blast stove (3) 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 reaction column (201) of a CO oxidation plant (2)3 Nm3/h：
Figure FDA0002261922840000043
That is, the flow rate of the CO oxidation apparatus (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 to ensure that the flow rate of the flue gas entering the preheating chamber (202) of the CO oxidation device (2) is U3 Nm3H, so that the temperature of the flue gas is reduced to T before entering the SCR reactor (1)Denitration℃。
CN201911074331.9A 2019-11-06 2019-11-06 CO oxidation and denitration system and method Active CN112403222B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201911074331.9A CN112403222B (en) 2019-11-06 2019-11-06 CO oxidation and denitration system and method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201911074331.9A CN112403222B (en) 2019-11-06 2019-11-06 CO oxidation and denitration system and method

Publications (2)

Publication Number Publication Date
CN112403222A true CN112403222A (en) 2021-02-26
CN112403222B CN112403222B (en) 2022-12-06

Family

ID=74779472

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201911074331.9A Active CN112403222B (en) 2019-11-06 2019-11-06 CO oxidation and denitration system and method

Country Status (1)

Country Link
CN (1) CN112403222B (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012245444A (en) * 2011-05-25 2012-12-13 Nippon Steel Corp Method for desulfurizing and denitrating sintering furnace exhaust gas
JP2013044265A (en) * 2011-08-23 2013-03-04 Ihi Corp Denitration apparatus and denitration method
CN103657404A (en) * 2013-12-06 2014-03-26 上海凯鸿环保工程有限公司 Tail gas catalysis combustion treatment system
WO2018006244A1 (en) * 2016-07-04 2018-01-11 中国科学院过程工程研究所 Microwave-selective catalytic reduction combined low-temperature denitration device, process and use
CN209348416U (en) * 2018-12-05 2019-09-06 江苏垦乐节能环保科技有限公司 A kind of de- CO system of sintering flue gas and desulfurizing and denitrifying

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012245444A (en) * 2011-05-25 2012-12-13 Nippon Steel Corp Method for desulfurizing and denitrating sintering furnace exhaust gas
JP2013044265A (en) * 2011-08-23 2013-03-04 Ihi Corp Denitration apparatus and denitration method
CN103657404A (en) * 2013-12-06 2014-03-26 上海凯鸿环保工程有限公司 Tail gas catalysis combustion treatment system
WO2018006244A1 (en) * 2016-07-04 2018-01-11 中国科学院过程工程研究所 Microwave-selective catalytic reduction combined low-temperature denitration device, process and use
CN209348416U (en) * 2018-12-05 2019-09-06 江苏垦乐节能环保科技有限公司 A kind of de- CO system of sintering flue gas and desulfurizing and denitrifying

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
张增志等: "《中国战略性新兴产业 新材料 环境工程材料》", 30 November 2018 *

Also Published As

Publication number Publication date
CN112403222B (en) 2022-12-06

Similar Documents

Publication Publication Date Title
CN112403258B (en) System and method for removing carbon monoxide and denitration of flue gas
CN104174287B (en) A kind of sintering machine partial fume denitrating system and method
CN107014217B (en) Coke oven gas utilization and flue gas treatment system of coking plant and treatment method thereof
CN111821852A (en) Device and process for jointly removing carbon monoxide and nitrogen oxides in sintering flue gas
CN112403221B (en) Flue gas denitration and decarburization treatment system and method
CN112403224B (en) CO oxidation and denitration system and method
US7648673B2 (en) Process for denoxification of off-gases from annealing and pickling lines, and an annealing and pickling line, especially for stainless steel hot or cold strip
CN107583430A (en) One kind sintering denitrating flue gas processing unit and method
CN112403223B (en) Heat exchange type system and method for removing carbon monoxide and denitration from flue gas
CN211753798U (en) CO oxidation and denitration system
CN112403222B (en) CO oxidation and denitration system and method
CN109668157B (en) Waste gas catalytic incineration treatment system and regulation control method thereof
CN112403220B (en) Heat exchange type flue gas denitration and decarburization treatment system and method
CN106382824A (en) Novel tube heating furnace waste heat recovery system and method
CN111167275A (en) Combined denitration device and process for chain grate-rotary kiln pellet production system
CN108261902B (en) Carbonization furnace tail gas treatment device and treatment method
CN112403181B (en) Flue gas desulfurization and denitrification treatment system and method
CN112774432B (en) Heat exchange system and process for SCR-RTO outlet flue gas
CN112403182B (en) Analytic tower and flue gas heating system
CN210021738U (en) Combined treatment system for realizing desulfurization and denitration of flue gas circulating fluidized bed under all working conditions
CN210107430U (en) Catalytic incineration treatment system suitable for treating volatile organic compound tail gas
CN210153831U (en) Organic waste gas catalytic combustion integrated device
CN206463756U (en) A kind of tail gas of carbonization stove processing unit
CN111841271A (en) Flue gas desulfurization and denitrification method and system by utilizing co-treatment of carbon monoxide
CN220143408U (en) Improved low-temperature Claus catalyst regenerating device

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant