WO2021128446A1 - 一种降低尾气氨排放的集成式催化转化系统及其方法 - Google Patents

一种降低尾气氨排放的集成式催化转化系统及其方法 Download PDF

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WO2021128446A1
WO2021128446A1 PCT/CN2020/070190 CN2020070190W WO2021128446A1 WO 2021128446 A1 WO2021128446 A1 WO 2021128446A1 CN 2020070190 W CN2020070190 W CN 2020070190W WO 2021128446 A1 WO2021128446 A1 WO 2021128446A1
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ammonia
catalyst
catalyst module
module
exhaust gas
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PCT/CN2020/070190
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English (en)
French (fr)
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李绚天
孙进
徐学骁
胡晓茜
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南京工大环境科技有限公司
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Publication of WO2021128446A1 publication Critical patent/WO2021128446A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8634—Ammonia
    • 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
    • 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
    • B01D2257/402—Dinitrogen oxide
    • 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
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/10—Capture or disposal of greenhouse gases of nitrous oxide (N2O)

Definitions

  • the invention belongs to the technical field of tail gas treatment equipment, and specifically relates to an integrated catalytic conversion system and a method for reducing tail gas ammonia emissions.
  • Ammonia escape is a common problem encountered in many industrial processes, such as ammonia scrubbers, amino CO 2 capture, and basic copper carbonate generation processes used in the semiconductor industry, where ammonia appears as a reactant, reaction product or pollutant.
  • concentration of fugitive ammonia can vary from a few ppmv to several percentages.
  • the measured odor threshold is 0.03–43mg/Nm 3. Therefore, when selecting and designing a flue gas purification system, the environmental and health effects of ammonia escape must be considered.
  • the conversion of ammonia can be achieved in three different ways:
  • the reaction is strongly endothermic and requires high temperature to reach a higher conversion rate.
  • the catalyst used is called an ammonia decomposition catalyst.
  • the reaction is a strongly exothermic reaction, so it requires a lower temperature from a thermodynamic point of view, but in order to overcome the limitation of reaction kinetics, a catalyst is required.
  • the catalyst used in this reaction is generally called an ammonia removal catalyst, and its active ingredient is generally a transition metal oxide.
  • platinum-based and cobalt-based (active component Co 3 O 4 ) catalysts are more commonly used.
  • an ammonia escape catalyst also known as ammonia removal catalyst, ammonia scavenging catalyst
  • this device is not designed for high concentration (>100ppmv) ammonia escape.
  • the ammonia removal catalyst used to remove the escaping ammonia gas is usually not enough to cope with the situation where the ammonia gas inlet concentration is higher than 500 ppmv, because side reactions will generate by-products such as N 2 O, NO, and NO 2.
  • the purpose of the present invention is to provide an integrated catalytic conversion system for reducing exhaust ammonia emissions on the basis of the prior art.
  • the present invention integrates an ammonia removal catalyst module, an ammonia oxidation catalyst module and a selective catalytic reduction catalyst module. It does not involve washing operation to process high-concentration ammonia waste gas, is not restricted by gas-liquid balance (VLE), and does not produce any waste water, and no secondary solid waste is generated.
  • VLE gas-liquid balance
  • Another object of the present invention is to provide a method for reducing exhaust ammonia emissions from the above-mentioned integrated catalytic conversion system.
  • An integrated catalytic conversion system for reducing exhaust ammonia emissions includes:
  • Exhaust gas inlet which is used to introduce exhaust gas flow
  • a flow interface expansion section is connected to the exhaust gas inlet, and an air distribution device is provided in the flow interface expansion section so that the airflow entering the flow interface expansion section can be evenly distributed when the flow interface expands;
  • a thermal management device which is arranged downstream of the flow interface expansion section, and is used to control the temperature of the exhaust gas flow derived from the flow interface expansion section;
  • Ammonia removal catalyst module the ammonia removal catalyst module is located downstream of the thermal management device, the ammonia removal catalyst module is used to make most of the NH 3 (ammonia) in the exhaust gas stream in the presence of free oxygen Gas) into N 2 (nitrogen) and H 2 O (water);
  • the ammonia oxidation catalyst module is located downstream of the ammonia removal catalyst module, and the ammonia oxidation catalyst module is used to make a small amount of NH 3 (ammonia gas) in the exhaust gas stream derived from the ammonia removal catalyst module ) And N 2 O (nitrogen monoxide) into NO (nitrogen monoxide) and NO 2 (nitrogen dioxide);
  • a selective catalytic reduction catalyst module the selective catalytic reduction catalyst module is located downstream of the ammonia oxidation catalyst module, the selective catalytic reduction catalyst module is used to lead out the ammonia oxidation catalyst module in the presence of NH 3 NO and NO 2 in the exhaust gas stream are converted into N 2 and H 2 O;
  • a tail gas outlet which is used to discharge the tail gas flow derived from the selective catalytic reduction catalyst module
  • the system also includes an airflow mixing device and an airflow bypass pipe:
  • the airflow mixing device is located downstream of the ammonia oxidation catalyst module; the inlet of the airflow mixing device is in communication with the outlet of the ammonia oxidation catalyst module; the outlet of the airflow mixing device is in communication with the inlet of the selective catalytic reduction catalyst module ;
  • the inlet of the airflow bypass pipe is communicated with the flow interface expansion section, the outlet of the airflow bypass pipe is communicated with the inlet of the airflow mixing device, and the airflow bypass pipe is provided with a control airflow bypass pipe.
  • Flow control valve for air flow is provided.
  • the ammonia removal catalyst module is composed of one or more granular beds containing ammonia removal catalyst or cut pieces of honeycomb type ammonia removal catalyst; the ammonia oxidation catalyst module is composed of one or more ammonia oxidation catalysts.
  • the granular bed or honeycomb type ammonia oxidation catalyst is composed of cut pieces;
  • the selective catalytic reduction catalyst module is composed of one or more granular beds or honeycomb type selective catalytic reduction catalyst containing cut pieces of selective catalytic reduction catalyst.
  • the active components of the ammonia removal catalyst used in the ammonia removal catalyst module mentioned in the present invention are transition metal oxides commonly used in the prior art, for example, metal oxides such as Cu, Mn, Co, Ti, and/or Zr. Things.
  • the above-mentioned ammonia removal catalyst can be, but not limited to: Co-Mn composite oxide catalyst, Cu-Mn composite oxide catalyst, Ti-Mn composite oxide catalyst, Zr-Mn composite oxide catalyst, Co-Cu-Mn composite oxide catalyst One or more of the chemical catalyst or the Co-Ti-Mn composite oxide catalyst.
  • the active components of the ammonia oxidation catalyst used in the ammonia oxidation catalyst module mentioned in the present invention are common noble metal oxides in the prior art, such as metal oxides such as Pt, Pd and/or Ag.
  • the ammoxidation catalyst can be, but not limited to: one or more of Pt-Ag composite oxide catalyst, Pt-Pd composite oxide catalyst, Ag-Pd composite oxide catalyst or Pt-Pd-Ag composite oxide catalyst .
  • the active components of the selective catalytic reduction catalyst used in the selective catalytic reduction catalyst module mentioned in the present invention are metal oxides such as metal V, W and/or Ti.
  • the above-mentioned selective catalytic reduction catalyst may be, but not limited to: one or more of V-W composite oxide catalyst, V-Ti composite oxide catalyst, W-Ti composite oxide catalyst or V-W-Ti composite oxide catalyst.
  • the inlet of the ammonia removal catalyst module is provided with a temperature sensor and an oxygen sensor; the downstream of the selective catalytic reduction catalyst module is provided with an ammonia detector.
  • a flow cross-section reduction section is provided between the selective catalytic reduction catalyst module and the tail gas outlet.
  • system further includes a controller, which is electrically connected to the thermal management device, and is used to control the airflow temperature at the inlet of the ammonia removal catalyst module; the controller is electrically connected to the flow control valve, and is used to control the airflow side. Air flow in the duct.
  • the controller can analyze the concentration of the escaped ammonia detected by the ammonia detector, the temperature of the exhaust gas to be treated containing ammonia, and the oxygen content, and feed it back to the flow control valve and thermal management device of the air flow in the air bypass pipe to achieve Control of the entire system.
  • the thermal management device controls the ratio between the fuel flow rate and the supply air flow rate according to the information fed back by the controller, and realizes effective control of the airflow temperature at the inlet of the ammonia removal catalyst module.
  • the system also includes a housing. Sealing gaskets are included between the inner side wall of the housing and the ammonia removal catalyst module, the ammonia oxidation catalyst module and the selective catalytic reduction catalyst module to prevent the exhaust gas to be processed from the ammonia removal catalyst module and ammonia oxidation. Leakage between the catalyst module and the selective catalytic reduction catalyst module and the gap between the housing.
  • the thermal management device is an external burner, a built-in burner, an electric heater, a heat exchanger or a combination thereof.
  • the fuel used is a fuel that is readily available in the prior art, such as but not limited to natural gas, liquefied petroleum gas (LPG), diesel, and air is used as the oxidant.
  • LPG liquefied petroleum gas
  • the thermal management device can be a built-in burner that uses all or part of the flue gas as the oxidant.
  • the present invention also includes a method for reducing exhaust ammonia emissions from the above-mentioned integrated catalytic conversion system, and the method includes:
  • the exhaust gas to be treated containing ammonia gas introduced from the tail gas inlet the exhaust gas containing ammonia gas with a volume ratio of 70 to 100% enters the ammonia removal catalyst module after temperature adjustment for the ammonia removal reaction, and then enters the ammonia oxidation catalyst
  • the module performs the ammonia oxidation reaction, and then introduces the selective catalytic reduction catalyst module to perform the selective reduction reaction; or, first introduces it into the gas flow mixing device, and mixes with the remaining ammonia-containing exhaust gas to be treated (volume ratio) introduced from the gas flow bypass pipe.
  • the time-average concentration of ammonia in the exhaust gas to be treated exceeds 500 ppmv and/or the ammonia in the exhaust gas to be treated
  • the peak instantaneous concentration of gas at the inlet exceeds 5000 ppmv.
  • the temperature of the gas stream at the inlet of the ammonia removal catalyst module is 250°C to 500°C, preferably 350°C to 450°C.
  • the conditions for the ammonia removal reaction include: oxygen volume concentration 8-21% (V/V); the reaction temperature is 250°C to 500°C, preferably 350°C to 450°C; the space velocity ratio is 5000-20000h -1 , Preferably 8000-12000h -1 ; the gas flow rate is 2-15 m ⁇ s -1 , preferably 5-10 m ⁇ s -1 ; the ammonia removal catalyst is a transition metal oxide; preferably a Co-Mn composite oxide catalyst, One or more of Cu-Mn composite oxide catalyst, Ti-Mn composite oxide catalyst, Zr-Mn composite oxide catalyst, Co-Cu-Mn composite oxide catalyst or Co-Ti-Mn composite oxide catalyst .
  • the conditions of the ammoxidation reaction include: the reaction temperature is 250°C to 500°C, preferably 350°C to 450°C; the space velocity ratio is 12000-50000h -1 , preferably 20000-30000h -1 ; the gas flow rate is 2-15m ⁇ s -1 , preferably 5-10 m ⁇ s -1 ; the ammonia oxidation catalyst is a noble metal oxide; preferably a Pt-Ag composite oxide catalyst, a Pt-Pd composite oxide catalyst, an Ag-Pd composite oxide catalyst, or Pt-Pd -One or more of Ag composite oxide catalysts.
  • the conditions of the selective catalytic reduction reaction include: the reaction temperature is 200°C to 450°C, preferably 300°C to 400°C; the space velocity ratio is 2000-10000h -1 , preferably 4000-6000h -1 ; the gas flow rate is 2-15m ⁇ S -1 , preferably 5-10m ⁇ s -1 ; the selective catalytic reduction catalyst is a VW composite oxide catalyst, a V-Ti composite oxide catalyst, a W-Ti composite oxide catalyst or a VW-Ti composite oxide catalyst One or more of them.
  • the present invention provides an integrated catalytic conversion system for reducing exhaust ammonia emissions, which integrates an ammonia removal catalyst module, an ammonia oxidation catalyst module and a selective catalytic reduction catalyst module. It does not involve washing operations to process high-concentration ammonia waste gas, and is not affected by gas. Liquid balance (VLE) is limited, and no waste water is produced, and no secondary solid waste is produced.
  • VLE Liquid balance
  • the method of the present invention is adopted to process high-concentration ammonia waste gas, with high efficiency, tail gas emission can meet the corresponding national standards, and can be guaranteed to be lower than the odor threshold of ammonia.
  • Figure 1 is a schematic diagram of a structure of the present invention
  • Figure 2 is a schematic diagram of the structure of a catalyst in the present invention.
  • Fig. 3 is a plan view of Fig. 2.
  • the integrated catalytic conversion system for reducing exhaust ammonia emissions includes:
  • An exhaust gas inlet 100 which is used to introduce exhaust gas flow
  • the flow interface expansion section 120 is connected to the exhaust gas inlet 100.
  • the flow interface expansion section 120 is provided with an air flow distribution that enables the air entering the flow interface expansion section 120 to be evenly distributed when the flow interface expands Device 130;
  • a thermal management device 150 which is provided downstream of the flow interface expansion section 120, and is used to control the temperature of the exhaust gas flow derived from the flow interface expansion section 120;
  • Ammonia removal catalyst module 200 the ammonia removal catalyst module 200 is located downstream of the thermal management device 150, the ammonia removal catalyst module 200 is used to make most of the exhaust gas flow in the presence of free oxygen NH 3 (ammonia) is converted into N 2 (nitrogen) and H 2 O (water);
  • the ammonia oxidation catalyst module 300 is located downstream of the ammonia removal catalyst module 200, and the ammonia oxidation catalyst module 300 is used to make a small amount of the exhaust gas flow derived from the ammonia removal catalyst module 200 NH 3 (ammonia) and N 2 O (nitrous oxide) are converted into NO (nitrogen monoxide) and NO 2 (nitrogen dioxide);
  • An airflow mixing device 350 which is located downstream of the ammonia oxidation catalyst module 300; the inlet of the airflow mixing device 350 is in communication with the outlet of the ammonia oxidation catalyst module 200;
  • An airflow bypass pipe 160 the inlet of the airflow bypass pipe 160 communicates with the flow interface expansion section 120, the outlet of the airflow bypass pipe 160 communicates with the inlet of the airflow mixing device 350, the airflow bypass pipe 160 is provided with a flow control valve 180 for controlling the air flow in the air bypass pipe;
  • the selective catalytic reduction catalyst module 400 is located downstream of the airflow mixing device 350, and the selective catalytic reduction catalyst module 400 is used to make the airflow mixing device in the presence of ammonia
  • the NO (nitrogen monoxide) and NO 2 (nitrogen dioxide) in the exhaust gas stream derived from 350 is converted into N 2 (nitrogen) and H 2 O (water);
  • the tail gas outlet 500 is used to discharge the tail gas flow derived from the selective catalytic reduction catalyst module 400.
  • the system also includes:
  • a temperature sensor 170 and an oxygen sensor 190 are provided at the entrance of the ammonia removal catalyst module 200.
  • An ammonia detector 450 is provided downstream of the selective catalytic reduction catalyst module 400.
  • a flow section reduction section 420 is provided between the selective catalytic reduction catalyst module 400 and the exhaust gas outlet 500.
  • the system also includes a controller 600 which is electrically connected to the thermal management device 150 for controlling the airflow temperature at the inlet of the ammonia removal catalyst module 200; the controller 600 is electrically connected to the flow control valve 180, To control the air flow in the air bypass pipe 160.
  • the controller 600 can analyze the concentration of the escaped ammonia gas detected by the ammonia detector 450, the temperature of the ammonia-containing exhaust gas to be treated, and the oxygen content, and feed it back to the flow control valve 180 and thermal management of the air flow in the air bypass pipe 160
  • the device 150 realizes the control of the entire system.
  • the thermal management device 150 controls the ratio between the fuel flow rate and the supply air flow rate according to the information fed back from the controller 600, so as to achieve effective control of the airflow temperature at the inlet of the ammonia removal catalyst module 200.
  • the system also includes a housing.
  • a gasket 210 is included between the inner side wall of the housing and the ammonia removal catalyst module 200, the ammonia oxidation catalyst module 300, and the selective catalytic reduction catalyst module 400 to prevent the exhaust gas to be treated from the ammonia removal catalyst.
  • the module 200, the ammonia oxidation catalyst module 300, and the selective catalytic reduction catalyst module 400 leak between the gaps of the casing.
  • the thermal management device 150 is an external burner, a built-in burner, an electric heater, a heat exchanger, or a combination thereof.
  • the fuel used is a fuel that is readily available in the prior art, such as but not limited to natural gas, liquefied petroleum gas (LPG), diesel, and air is used as the oxidant.
  • LPG liquefied petroleum gas
  • the thermal management device 150 may be a built-in burner that uses all or part of the flue gas as the oxidant.
  • the ammonia removal catalyst module 200 is composed of one or more granular beds containing ammonia removal catalyst or cut pieces of honeycomb type ammonia removal catalyst;
  • the ammonia oxidation catalyst module 300 is It is composed of one or more particle beds or honeycomb type ammonia oxidation catalyst cuts containing ammonia oxidation catalyst;
  • the selective catalytic reduction catalyst module 400 is composed of one or more particle beds or honeycomb type ammonia oxidation catalyst containing selective catalytic reduction catalysts.
  • the selective catalytic reduction catalyst is composed of cut pieces.
  • the present invention also includes a method for reducing exhaust ammonia emissions from the above-mentioned integrated catalytic conversion system, and the method includes:
  • the exhaust gas to be treated containing ammonia gas introduced from the exhaust gas inlet 100 the exhaust gas containing ammonia gas with a volume ratio of 70-100% after temperature adjustment enters the ammonia removal catalyst module 200 for ammonia removal reaction, and then enters the ammonia
  • the oxidation catalyst module 300 performs the ammonia oxidation reaction, and then introduces the selective catalytic reduction catalyst module 400 to perform the selective reduction reaction; alternatively, it is first introduced into the airflow mixing device 350, and the remaining ammonia-containing gas introduced from the airflow bypass pipe 160 After the exhaust gas to be treated (volume ratio is 0-30%) is mixed, it is then introduced into the selective catalytic reduction catalyst module 400 for selective reduction reaction; wherein, the time-average concentration of ammonia in the exhaust gas to be treated exceeds 500 ppmv and/or The peak value of the inlet instantaneous concentration of ammonia in the exhaust gas to be treated exceeds 5000 ppmv.
  • the temperature of the gas stream at the inlet of the ammonia removal catalyst module 200 is 250°C to 500°C, preferably 350°C to 450°C.
  • the conditions for the ammonia removal reaction include: oxygen volume concentration 8-21% (V/V); the reaction temperature is 250°C to 500°C, preferably 350°C to 450°C; the space velocity ratio is 5000-20000h -1 , Preferably 8000-12000h -1 ; the gas flow rate is 2-15 m ⁇ s -1 , preferably 5-10 m ⁇ s -1 ; the ammonia removal catalyst is a transition metal oxide; preferably a Co-Mn composite oxide catalyst, One or more of Cu-Mn composite oxide catalyst, Ti-Mn composite oxide catalyst, Zr-Mn composite oxide catalyst, Co-Cu-Mn composite oxide catalyst or Co-Ti-Mn composite oxide catalyst .
  • the conditions of the ammoxidation reaction include: the reaction temperature is 250°C to 500°C, preferably 350°C to 450°C; the space velocity ratio is 12000-50000h -1 , preferably 20000-30000h -1 ; the gas flow rate is 2-15m ⁇ s -1 , preferably 5-10 m ⁇ s -1 ; the ammonia oxidation catalyst is a noble metal oxide; preferably a Pt-Ag composite oxide catalyst, a Pt-Pd composite oxide catalyst, an Ag-Pd composite oxide catalyst, or Pt-Pd -One or more of Ag composite oxide catalysts.
  • the conditions of the ammoxidation reaction include: the reaction temperature is 200°C to 450°C, preferably 300°C to 400°C; the space velocity ratio is 2000-10000h -1 , preferably 4000-6000h -1 ; the gas flow rate is 2-15m ⁇ s -1 , preferably 5-10 m ⁇ s -1 ; the selective catalytic reduction catalyst is a VW composite oxide catalyst, a V-Ti composite oxide catalyst, a W-Ti composite oxide catalyst or a VW-Ti composite oxide catalyst One or more.
  • the treatment efficiency of this system for ammonia-containing tail gas is: NH 3 removal rate ⁇ 99.9% or tail gas NH 3 concentration ⁇ 10 mg/Nm 3 , N 2 selectivity ⁇ 99% or tail gas NOx concentration ⁇ 100 mg/Nm 3 (the best quasi).
  • the 2000ppmv ammonia-containing exhaust gas to be treated is introduced from the exhaust gas inlet 100 into the flow interface expansion section 120, wherein 100% (V/V) of the ammonia-containing exhaust gas to be treated enters the flow interface under the action of the air distribution device 130
  • the air flow inside the expansion section 120 is evenly distributed when the flow interface is expanded, and then enters the thermal management device 150 (external burner) to adjust the temperature. After the temperature is adjusted, it enters the ammonia removal catalyst module 200 for the ammonia removal reaction.
  • the control temperature is 250°C, space velocity ratio of 5000h -1 , gas flow rate 2m ⁇ s -1
  • the catalyst is a Co-Mn composite oxide catalyst, which converts most of the NH 3 (ammonia) in the exhaust gas stream containing ammonia gas to be treated N 2 (nitrogen) and H 2 O (water).
  • the exhaust gas stream enters the ammonia oxidation catalyst module 300 to perform the ammonia oxidation reaction.
  • the control temperature is 200°C, the space velocity ratio is 12000h -1 , the gas flow rate is 2m ⁇ s -1 , and the catalyst is Pt-Ag composite oxidation.
  • the exhaust gas stream is then introduced into the selective catalytic reduction catalyst module 400 for selective reduction reaction.
  • the control temperature is 200°C
  • the space velocity ratio is 2000h -1
  • the gas flow rate is 2m ⁇ s -1
  • the catalyst is VW composite oxidation. ⁇ catalyst.
  • the controller 600 analyzes the concentration of the escaped ammonia gas detected by the ammonia detector 450, the temperature of the ammonia-containing exhaust gas to be processed detected by the temperature sensor 170, and the oxygen content detected by the oxygen sensor 190, so as to realize the control of the entire system.
  • NH 3 removal rate is 99.9%
  • tail gas NH 3 concentration is 1.52 mg/Nm 3
  • N 2 selectivity is 99%
  • tail gas NOx concentration is 44.1 mg/Nm 3 .
  • the exhaust gas to be treated containing 5000ppmv ammonia gas is introduced from the exhaust gas inlet 100 into the flow interface expansion section 120.
  • 85% (V/V) of the exhaust gas to be treated containing ammonia gas enters the flow interface under the action of the air distribution device 130
  • the air flow inside the expansion section 120 is evenly distributed when the flow interface is expanded, and then enters the thermal management device 150 (external burner) to adjust the temperature. After the temperature is adjusted, it enters the ammonia removal catalyst module 200 for the ammonia removal reaction.
  • the control temperature is 400°C
  • space velocity ratio is 10000h -1
  • gas flow rate is 8m ⁇ s -1
  • the catalyst is Cu-Mn composite oxide catalyst, which converts most of the NH 3 (ammonia) in the exhaust gas stream containing ammonia gas to be treated N 2 (nitrogen) and H 2 O (water).
  • the exhaust gas stream enters the ammonia oxidation catalyst module 300 to perform the ammonia oxidation reaction.
  • the control temperature is 400°C
  • the space velocity ratio is 25000h -1
  • the gas flow rate is 8 m ⁇ s -1
  • the catalyst is Pt-Pd composite oxidation.
  • the catalyst converts NH 3 (ammonia) and N 2 O (nitrous oxide) into NO (nitrogen monoxide) and NO 2 (nitrogen dioxide).
  • the exhaust gas stream is then introduced into the gas flow mixing device 350, mixed with the 15% (V/V) ammonia-containing exhaust gas to be treated introduced by the gas bypass pipe 160, and then introduced into the selective catalytic reduction catalyst
  • the module 400 performs a selective reduction reaction, the control temperature is 350° C., the space velocity ratio is 5000 h -1 , the gas flow rate is 8 m ⁇ s -1 , and the catalyst is a VW-Ti composite oxide catalyst.
  • the discharged tail gas flow passes through the flow cross-section reduction section 420, and then is discharged from the tail gas outlet 500.
  • the controller 600 analyzes the concentration of the escaped ammonia gas detected by the ammonia detector 450, the temperature of the exhaust gas to be processed containing the ammonia gas detected by the temperature sensor 170, and the oxygen content detected by the oxygen sensor 190, and feeds them back to the airflow flow rate in the airflow bypass pipe 160
  • the flow control valve 180 and the thermal management device 150 realize the control of the entire system.
  • NH 3 removal rate is 99.95%
  • tail gas NH 3 concentration is 1.90 mg/Nm 3
  • N 2 selectivity is 99.5%
  • tail gas NOx concentration is 51.3 mg/Nm 3 .
  • the 10000ppmv ammonia-containing exhaust gas to be treated is introduced from the exhaust gas inlet 100 into the flow interface expansion section 120, wherein 70% (V/V) of the ammonia-containing exhaust gas to be treated enters the flow interface under the action of the air distribution device 130
  • the air flow inside the expansion section 120 is evenly distributed when the flow interface is expanded, and then enters the thermal management device 150 (external burner) to adjust the temperature. After the temperature is adjusted, it enters the ammonia removal catalyst module 200 for the ammonia removal reaction.
  • the control temperature is 500°C
  • space velocity ratio is 20000h -1
  • gas flow rate is 15m ⁇ s -1
  • the catalyst is Co-Cu-Mn composite oxide catalyst, so that most of the NH 3 (ammonia) in the exhaust gas stream to be treated containing ammonia Converted to N 2 (nitrogen) and H 2 O (water).
  • the tail gas stream enters the ammonia oxidation catalyst module 300 to perform the ammonia oxidation reaction.
  • the control temperature is 500°C
  • the space velocity ratio is 50000 h -1
  • the gas flow rate is 15 m ⁇ s -1
  • the catalyst is Pt-Pd-Ag
  • the composite oxide catalyst converts NH 3 (ammonia) and N 2 O (nitrous oxide) into NO (nitrogen monoxide) and NO 2 (nitrogen dioxide).
  • the exhaust gas stream is introduced into the gas stream mixing device 350, mixed with the 30% (V/V) ammonia-containing exhaust gas to be treated introduced by the gas bypass pipe 160, and then introduced into the selective catalytic reduction catalyst
  • the module 400 performs selective reduction reaction, the control temperature is 450° C., the space velocity ratio is 10000 h -1 , the gas flow rate is 15 m ⁇ s -1 , and the catalyst is a VW-Ti composite oxide catalyst.
  • the discharged tail gas flow passes through the flow cross-section reduction section 420, and then is discharged from the tail gas outlet 500.
  • the controller 600 analyzes the concentration of the escaped ammonia gas detected by the ammonia detector 450, the temperature of the ammonia-containing exhaust gas to be processed detected by the temperature sensor 170, and the oxygen content detected by the oxygen sensor 190, and feeds them back to the airflow flow rate in the airflow bypass pipe 160
  • the flow control valve 180 and the thermal management device 150 realize the control of the entire system.
  • NH 3 removal rate is 99.95%
  • tail gas NH 3 concentration is 3.79 mg/Nm 3
  • N 2 selectivity is 99.8%
  • tail gas NOx concentration is 41.1 mg/Nm 3 .
  • Example 1 Example 2 Example 3 Instantaneous concentration of ammonia-containing exhaust gas (ppmv) 2000 5000 10000 Ammonia removal reaction temperature (°C) 250 400 500 Ammonia removal space velocity ratio (h -1 ) 5000 10000 20000 Ammoxidation reaction temperature (°C) 200 400 500 Ammoxidation space velocity ratio (h -1 ) 12000 25000 50000 Selective reduction reaction temperature (°C) 200 350 450 Selective reduction space velocity ratio (h -1 ) 2000 5000 10000 Gas distribution ratio (%) 0 15 30 Exhaust gas flow rate (m ⁇ s -1 ) 2 8 15 NH 3 removal rate (%) 99.9 99.95 99.95 Exhaust NH 3 concentration (mg/Nm 3 ) 1.52 1.90 3.79 N 2 selectivity (%) 99 99.5 99.8 Exhaust NOx concentration (mg/Nm 3 ) 41.1 51.3 41.1

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Abstract

提供一种降低尾气氨排放的集成式催化转化系统及其方法，该系统集氨脱除催化剂模块（200）、氨氧化催化剂模块（300）和选择性催化还原催化剂模块（400）于一体，控制氨脱除、氨氧化和选择性催化还原反应的温度、空速比和气体流速，对高浓度氨废气进行处理时，效率高，尾气排放可以满足国家相应标准，同时，不涉及洗涤操作进行处理高浓度氨废气，不受气液平衡(VLE)的限制，也不会产生任何废水，无二次固废产生。

Description

一种降低尾气氨排放的集成式催化转化系统及其方法 技术领域
本发明属于尾气处理设备技术领域，具体涉及一种降低尾气氨排放的集成式催化转化系统及其方法。
背景技术
氨逃逸是多种工业过程中遇到的共性问题，例如氨气洗涤塔、氨基CO 2捕获和用于半导体工业的碱式碳酸铜生成过程，其中氨作为反应物、反应产物或污染物出现。逃逸氨的浓度可以从几个ppmv到若干百分率之间不等。
鉴于NH 3是一种低嗅阈值的刺激性恶臭气体，实测嗅阈值为0.03–43mg/Nm 3，因此在选择和设计烟气净化系统时，必须考虑氨逃逸的环境和健康效应。
氨的转化可以通过三种不同途径来实现：
一是在催化剂存在条件下进行氨还原或氨分解反应(R1):
2NH 3＝N 2+3H 2,
ΔH 298＝109.0kJ/mol    (R1)
该反应是强烈吸热的，需在高温下才能达到较高转化率。所用催化剂称为氨分解催化剂。
另一种途径是在温和氧化性气氛中，并有催化剂存在的条件下，进行氨脱除反应(R2):
4NH 3+3O 2＝2N 2+6H 2O,
ΔH 298＝–1269.0kJ/mol    (R2)
该反应是强烈放热反应，因此从热力学角度它要求的温度较低，但为了克服反应动力学限制，需要使用催化剂。用于这一反应的催化剂通称为氨脱除催化剂，其活性成分一般是过渡金属氧化物。
第三种途径是，在更强的氧化性气氛中，例如在硝酸生产过程中，氨会在催化剂存在时被进一步氧化：
4NH 3+5O 2＝4NO+6H 2O,
ΔH 298＝–907.3kJ/mol    (R3)
现有氨氧化催化剂中，较常用的是铂基和钴基(活性成分为Co 3O 4)催化剂。
为了减少氨逃逸，最优选的反应是(R2)。但是，该反应对最希望的产物(即N 2)的选择性受到反应(R3)的影响，甚至会受到更不希望出现的如下反应的影响：
4NH 3+4O 2＝2N 2O+6H 2O,
ΔH 298＝–1104.9kJ/mol    (R4)
在各种烟气系统中，温度和氧浓度的变化范围很广，因此上述副反应和副产物在真实应用中几乎无可避免。因此，可靠的脱氨系统和方法必须考虑这些副反应，并能有效地克服它们的不利影响。
解决从选择性催化还原(SCR)过程中的氨逃逸问题的现有技术中，通常会采用一种氨逃逸催化剂(亦称氨脱除催化剂、氨清除催化剂)。然而，这种装置不是针对高浓度(>100ppmv)氨逃逸设计的。
在单独使用时，用于脱除逃逸氨气的氨脱除催化剂通常不足以应对氨气入口浓度高于500ppmv的情况，因为副反应会生成N 2O、NO和NO 2等副产物。
发明内容
本发明的目的是在现有技术的基础上，提供一种降低尾气氨排放的集成式催化转化系统，本发明集氨脱除催化剂模块、氨氧化催化剂模块和选择性催化还原催化剂模块于一体，不涉及洗涤操作进行处理高浓度氨废气，不受气液平衡(VLE)的限制，也不会产生任何废水，无二次固废产生。
本发明的另一目的是提供一种上述集成式催化转化系统降低尾气氨排放的方法。
本发明的技术方案如下：
一种降低尾气氨排放的集成式催化转化系统，该系统包括：
尾气入口，该尾气入口用于导入尾气气流；
流动界面扩张段，该流动界面扩张段与尾气入口连接，在所述流动界面扩张段内设有使进入流动界面扩张段内部的气流在流动界面扩大时能均匀分配的气流分配装置；
热管理装置，该热管理装置设于所述流动界面扩张段的下游，用于控制从所述流动界面扩张段导出的尾气气流的温度；
氨脱除催化剂模块，该氨脱除催化剂模块位于所述热管理装置的下游，所述氨脱除催化剂模块用于在自由氧存在的条件下使所述尾气气流中的大部分NH 3(氨气)转化为N 2(氮气)和H 2O(水)；
氨氧化催化剂模块，该氨氧化催化剂模块位于所述氨脱除催化剂模块的下游，所述氨 氧化催化剂模块用于使所述氨脱除催化剂模块导出的尾气气流中的少量的NH 3(氨气)和N 2O(一氧化二氮)转化为NO(一氧化氮)和NO 2(二氧化氮)；
选择性催化还原催化剂模块，该选择性催化还原催化剂模块位于所述氨氧化催化剂模块的下游，所述选择性催化还原催化剂模块用于在NH 3存在的条件下使所述氨氧化催化剂模块导出的尾气气流中的NO和NO 2转化为N 2和H 2O；以及
尾气出口，该尾气出口用于排出所述选择性催化还原催化剂模块导出的尾气气流；
或者，该系统还包括气流混合装置和气流旁通管：
所述气流混合装置位于所述氨氧化催化剂模块的下游；所述气流混合装置的入口与所述氨氧化催化剂模块的出口连通；所述气流混合装置的出口与选择性催化还原催化剂模块的入口连通；
所述气流旁通管的入口与所述流动界面扩张段连通，所述气流旁通管的出口与所述气流混合装置的入口连通，所述气流旁通管上设有控制气流旁通管中气流流量的流量控制阀。
进一步的，氨脱除催化剂模块是由一个或多个包含氨脱除催化剂的颗粒床层或蜂窝型氨脱除催化剂的切块组成；氨氧化催化剂模块是由一个或多个包含氨氧化催化剂的颗粒床层或蜂窝型氨氧化催化剂的切块组成；选择性催化还原催化剂模块是由一个或多个包含选择性催化还原催化剂的颗粒床层或蜂窝型选择性催化还原催化剂的切块组成。
本发明提及的氨脱除催化剂模块中所使用的氨脱除催化剂，其活性成分为现有技术中常见的过渡金属氧化物，例如，Cu、Mn、Co、Ti和/或Zr等金属氧化物。上述氨脱除催化剂可以但不局限于：Co-Mn复合氧化物催化剂、Cu-Mn复合氧化物催化剂、Ti-Mn复合氧化物催化剂、Zr-Mn复合氧化物催化剂、Co-Cu-Mn复合氧化物催化剂或Co-Ti-Mn复合氧化物催化剂中的一种或几种。
本发明提及的氨氧化催化剂模块中所使用的氨氧化催化剂，其活性成分为现有技术中常见的贵金属氧化物，例如Pt、Pd和/或Ag等金属氧化物。上述氨氧化催化剂可以但不局限于：Pt-Ag复合氧化物催化剂、Pt-Pd复合氧化物催化剂、Ag-Pd复合氧化物催化剂或Pt-Pd-Ag复合氧化物催化剂中的一种或几种。
本发明提及的选择性催化还原催化剂模块中所使用的选择性催化还原催化剂，其活性成分为金属V、W和/或Ti等金属氧化物。上述选择性催化还原催化剂可以但不局限于：V-W复合氧化物催化剂、V-Ti复合氧化物催化剂、W-Ti复合氧化物催化剂或V-W-Ti复合氧化物催化剂中的一种或几种。
进一步的，氨脱除催化剂模块的入口处设有温度传感器和氧传感器；选择性催化还原催化剂模块的下游设有氨检测器。
进一步的，选择性催化还原催化剂模块与尾气出口之间设有流动截面缩减段。
进一步的，系统还包括控制器，该控制器与热管理装置电性连接，用于控制氨脱除催化剂模块的入口处的气流温度；控制器与流量控制阀电性连接，用于控制气流旁通管中气流流量。
控制器可以针对氨检测器检测到的逃逸氨气浓度、含氨气的待处理尾气温度、氧含量进行分析，并反馈至气流旁通管中气流流量的流量控制阀和热管理装置，实现对整个系统的控制。
热管理装置根据控制器反馈的信息，从而控制燃料流量和送风流量之间的比例，实现对氨脱除催化剂模块的入口处的气流温度的有效控制。
进一步的，本系统还包括外壳，外壳的内侧壁与氨脱除催化剂模块、氨氧化催化剂模块和选择性催化还原催化剂模块之间包含密封垫，防止待处理尾气从氨脱除催化剂模块、氨氧化催化剂模块和选择性催化还原催化剂模块与壳体的缝隙之间泄漏。
进一步的，热管理装置为外置式燃烧器、内置式燃烧器、电加热器、换热器或其组合。本发明采用的热管理装置为外置式燃烧器时，所使用的燃料为现有技术中易得的燃料，例如但不限于天然气、液化石油气(LPG)、柴油，并以空气为氧化剂。当烟气中自由氧浓度较高时，热管理装置可以是一台内置式燃烧器，以全部或部分烟气作为氧化剂。
本发明还包括上述集成式催化转化系统降低尾气氨排放的方法，该方法包括：
由尾气入口导入的含氨气的待处理尾气中，体积比为70～100％的含氨气的待处理尾气经过温度调节后进入氨脱除催化剂模块进行氨脱除反应，再进入氨氧化催化剂模块进行氨氧化反应，然后导入选择性催化还原催化剂模块进行选择性还原反应；或者，先导入气流混合装置中，与剩余的由气流旁通管中导入的含氨气的待处理尾气(体积比为0～30％)进行混合后，然后导入选择性催化还原催化剂模块进行选择性还原反应；其中，所述待处理尾气中氨气的时均浓度超过500ppmv和/或所述待处理尾气中氨气的入口瞬时浓度峰值超过5000ppmv。
氨脱除催化剂模块入口处的气流温度为250℃～500℃，优选为350℃～450℃。
进一步的，氨脱除反应的条件包括：氧体积浓度8-21％(V/V)；反应温度为250℃～500℃，优选为350℃～450℃；空速比为5000-20000h -1，优选为8000-12000h -1；气体流速为2-15m·s -1，优选为5-10m·s -1；氨脱除催化剂为过渡金属氧化物；优选为Co-Mn 复合氧化物催化剂、Cu-Mn复合氧化物催化剂、Ti-Mn复合氧化物催化剂、Zr-Mn复合氧化物催化剂、Co-Cu-Mn复合氧化物催化剂或Co-Ti-Mn复合氧化物催化剂中的一种或几种。
氨氧化反应的条件包括：反应温度为250℃～500℃，优选为350℃～450℃；空速比为12000-50000h -1，优选为20000-30000h -1；气体流速为2-15m·s -1，优选为5-10m·s -1；氨氧化催化剂为贵金属氧化物；优选为Pt-Ag复合氧化物催化剂、Pt-Pd复合氧化物催化剂、Ag-Pd复合氧化物催化剂或Pt-Pd-Ag复合氧化物催化剂中的一种或几种。
选择性催化还原反应的条件包括：反应温度为200℃～450℃，优选为300℃～400℃；空速比为2000-10000h -1，优选为4000-6000h -1；气体流速为2-15m·s -1，优选为5-10m·s -1；选择性催化还原催化剂为V-W复合氧化物催化剂、V-Ti复合氧化物催化剂、W-Ti复合氧化物催化剂或V-W-Ti复合氧化物催化剂中的一种或几种。
采用本发明的技术方案，优势如下:
本发明提供一种降低尾气氨排放的集成式催化转化系统，集氨脱除催化剂模块、氨氧化催化剂模块和选择性催化还原催化剂模块于一体，不涉及洗涤操作进行处理高浓度氨废气，不受气液平衡(VLE)的限制，也不会产生任何废水，无二次固废产生。采用本发明的方法处理高浓度氨废气，效率高，尾气排放可以满足国家相应标准，可确保低于氨气的嗅阈值。
附图说明
图1是本发明的一种结构示意图；
其中，100是尾气入口；120是流动界面扩张段；130是气流分配装置；150是热管理装置；160是气流旁通管；170是温度传感器；180是流量控制阀；190是氧传感器；200是氨脱除催化剂模块；300是氨氧化催化剂模块；350是气流混合装置；400是选择性催化还原催化剂模块；420是流动截面缩减段；450是氨检测器；500是尾气出口；600是控制器；
图2是本发明中的一种催化剂的结构示意图；
图3是图2的俯视图。
具体实施方式
通过以下实施例并结合附图对本发明的降低尾气氨排放的集成式催化转化系统作进一步的说明，但这些实施例不对本发明构成任何限制。
如图1所示，本发明提供的降低尾气氨排放的集成式催化转化系统，该系统包括：
尾气入口100，该尾气入口100用于导入尾气气流；
流动界面扩张段120，该流动界面扩张段120与尾气入口100连接，在所述流动界面扩张段120内设有使进入流动界面扩张段120内部的气流在流动界面扩大时能均匀分配的气流分配装置130；
热管理装置150，该热管理装置150设于所述流动界面扩张段120的下游，用于控制从所述流动界面扩张段120导出的尾气气流的温度；
氨脱除催化剂模块200，该氨脱除催化剂模块200位于所述热管理装置150的下游，所述氨脱除催化剂模块200用于在自由氧存在的条件下使所述尾气气流中的大部分NH 3(氨气)转化为N 2(氮气)和H 2O(水)；
氨氧化催化剂模块300，该氨氧化催化剂模块300位于所述氨脱除催化剂模块200的下游，所述氨氧化催化剂模块300用于使所述氨脱除催化剂模块200导出的尾气气流中的少量的NH 3(氨气)和N 2O(一氧化二氮)转化为NO(一氧化氮)和NO 2(二氧化氮)；
气流混合装置350，该气流混合装置350位于所述氨氧化催化剂模块300的下游；所述气流混合装置350的入口与所述氨氧化催化剂模块200的出口连通；
气流旁通管160，该气流旁通管160的入口与所述流动界面扩张段120连通，所述气流旁通管160的出口与所述气流混合装置350的入口连通，所述气流旁通管160上设有控制气流旁通管中气流流量的流量控制阀180；
选择性催化还原催化剂模块400，该选择性催化还原催化剂模块400位于所述气流混合装置350的下游，所述选择性催化还原催化剂模块400用于在氨气存在的条件下使所述气流混合装置350导出的尾气气流中的NO(一氧化氮)和NO 2(二氧化氮)转化为N 2(氮气)和H 2O(水)；
尾气出口500，该尾气出口500用于排出所述选择性催化还原催化剂模块400导出的尾气气流。
该系统还包括：
在氨脱除催化剂模块200的入口处设有温度传感器170和氧传感器190.
在选择性催化还原催化剂模块400的下游设有氨检测器450。
在选择性催化还原催化剂模块400与尾气出口500之间设有流动截面缩减段420。
本系统还包括控制器600，该控制器600与热管理装置150电性连接，用于控制氨脱除催化剂模块200的入口处的气流温度；控制器600与流量控制阀180电性连接，用于控制气流旁通管160中气流流量。
控制器600可以针对氨检测器450检测到的逃逸氨气浓度、含氨气的待处理尾气温度、氧含量进行分析，并反馈至气流旁通管160中气流流量的流量控制阀180和热管理装置150，实现对整个系统的控制。
热管理装置150根据控制器600反馈的信息，从而控制燃料流量和送风流量之间的比例，实现对氨脱除催化剂模块200的入口处的气流温度的有效控制。
进一步的，本系统还包括外壳，外壳的内侧壁与氨脱除催化剂模块200、氨氧化催化剂模块300和选择性催化还原催化剂模块400之间包含密封垫210，防止待处理尾气从氨脱除催化剂模块200、氨氧化催化剂模块300和选择性催化还原催化剂模块400与壳体的缝隙之间泄漏。
进一步的，热管理装置150为外置式燃烧器、内置式燃烧器、电加热器、换热器或其组合。本发明采用的热管理装置150为外置式燃烧器时，所使用的燃料为现有技术中易得的燃料，例如但不限于天然气、液化石油气(LPG)、柴油，并以空气为氧化剂。当烟气中自由氧浓度较高时，热管理装置150可以是一台内置式燃烧器，以全部或部分烟气作为氧化剂。
如图1、2和图3所示，氨脱除催化剂模块200是由一个或多个包含氨脱除催化剂的颗粒床层或蜂窝型氨脱除催化剂的切块组成；氨氧化催化剂模块300是由一个或多个包含氨氧化催化剂的颗粒床层或蜂窝型氨氧化催化剂的切块组成；选择性催化还原催化剂模块400是由一个或多个包含选择性催化还原催化剂的颗粒床层或蜂窝型选择性催化还原催化剂的切块组成。
本发明还包括上述集成式催化转化系统降低尾气氨排放的方法，该方法包括：
由尾气入口100导入的含氨气的待处理尾气中，体积比为70～100％的含氨气的待处理尾气经过温度调节后进入氨脱除催化剂模块200进行氨脱除反应，再进入氨氧化催化剂模块300进行氨氧化反应，然后导入选择性催化还原催化剂模块400进行选择性还原反应；或者，先导入气流混合装置350中，与剩余的由气流旁通管160中导入的含氨气的待处理尾气(体积比为0～30％)进行混合后，然后导入选择性催化还原催化剂模块400进行选择性还原反应；其中，所述待处理尾气中氨气的时均浓度超过500ppmv和/或所述待处理尾气中氨气的入口瞬时浓度峰值超过5000ppmv。
氨脱除催化剂模块200入口处的气流温度为250℃～500℃，优选为350℃～450℃。
进一步的，氨脱除反应的条件包括：氧体积浓度8-21％(V/V)；反应温度为250℃～500℃，优选为350℃～450℃；空速比为5000-20000h -1，优选为8000-12000h -1； 气体流速为2-15m·s -1，优选为5-10m·s -1；氨脱除催化剂为过渡金属氧化物；优选为Co-Mn复合氧化物催化剂、Cu-Mn复合氧化物催化剂、Ti-Mn复合氧化物催化剂、Zr-Mn复合氧化物催化剂、Co-Cu-Mn复合氧化物催化剂或Co-Ti-Mn复合氧化物催化剂中的一种或几种。
氨氧化反应的条件包括：反应温度为250℃～500℃，优选为350℃～450℃；空速比为12000-50000h -1，优选为20000-30000h -1；气体流速为2-15m·s -1，优选为5-10m·s -1；氨氧化催化剂为贵金属氧化物；优选为Pt-Ag复合氧化物催化剂、Pt-Pd复合氧化物催化剂、Ag-Pd复合氧化物催化剂或Pt-Pd-Ag复合氧化物催化剂中的一种或几种。
氨氧化反应的条件包括：反应温度为200℃～450℃，优选为300℃～400℃；空速比为2000-10000h -1，优选为4000-6000h -1；气体流速为2-15m·s -1，优选为5-10m·s -1；选择性催化还原催化剂为V-W复合氧化物催化剂、V-Ti复合氧化物催化剂、W-Ti复合氧化物催化剂或V-W-Ti复合氧化物催化剂中的一种或几种。
本系统对含氨尾气的处理效率为：NH 3去除率≥99.9％或尾气NH 3浓度≤10mg/Nm 3，N 2选择性≥99％或尾气NOx浓度≤100mg/Nm 3(以最优为准)。
实施例1
由尾气入口100导入2000ppmv含氨气的待处理尾气进入流动界面扩张段120中，其中，100％(V/V)含氨气的待处理尾气在气流分配装置130的作用下，使进入流动界面扩张段120内部的气流在流动界面扩大时均匀分配，再进入热管理装置150(外置式燃烧器)进行调节温度，待温度调节后进入氨脱除催化剂模块200进行氨脱除反应，控制温度为250℃、空速比为5000h -1，气体流速2m·s -1，催化剂为Co-Mn复合氧化物催化剂，使含氨气的待处理尾气气流中的大部分NH 3(氨气)转化为N 2(氮气)和H 2O(水)。氨脱除反应完成后的尾气气流再进入氨氧化催化剂模块300进行氨氧化反应，控制温度为200℃、空速比为12000h -1，气体流速2m·s -1，催化剂为Pt-Ag复合氧化物催化剂，使NH 3(氨气)和N 2O(一氧化二氮)转化为NO(一氧化氮)和NO 2(二氧化氮)。氨氧化反应完成后的尾气气流再导入选择性催化还原催化剂模块400进行选择性还原反应，控制温度为200℃、空速比为2000h -1，气体流速2m·s -1，催化剂为V-W复合氧化物催化剂。选择性还原反应完成后导出的尾气气流经过流动截面缩减段420，再由尾气出口500排出。
控制器600针对氨检测器450检测的逃逸氨气浓度、温度传感器170检测的含氨气的待处理尾气温度以及氧传感器190检测的氧含量进行分析，实现对整个系统的控制。
处理结果：NH 3去除率99.9％，尾气NH 3浓度1.52mg/Nm 3，N 2选择性99％，尾气NOx浓度44.1mg/Nm 3。
实施例2
由尾气入口100导入5000ppmv含氨气的待处理尾气进入流动界面扩张段120中，其中，85％(V/V)含氨气的待处理尾气在气流分配装置130的作用下，使进入流动界面扩张段120内部的气流在流动界面扩大时均匀分配，再进入热管理装置150(外置式燃烧器)进行调节温度，待温度调节后进入氨脱除催化剂模块200进行氨脱除反应，控制温度为400℃、空速比为10000h -1，气体流速8m·s -1，催化剂为Cu-Mn复合氧化物催化剂，使含氨气的待处理尾气气流中的大部分NH 3(氨气)转化为N 2(氮气)和H 2O(水)。氨脱除反应完成后的尾气气流再进入氨氧化催化剂模块300进行氨氧化反应，控制温度为400℃、空速比为25000h -1，气体流速8m·s -1，催化剂为Pt-Pd复合氧化物催化剂，使NH 3(氨气)和N 2O(一氧化二氮)转化为NO(一氧化氮)和NO 2(二氧化氮)。氨氧化反应完成后的尾气气流再导入气流混合装置350中，与由气流旁通管160导入的15％(V/V)的含氨气的待处理尾气混合后，再导入选择性催化还原催化剂模块400进行选择性还原反应，控制温度为350℃、空速比为5000h -1，气体流速8m·s -1，催化剂为V-W-Ti复合氧化物催化剂。选择性还原反应完成后导出的尾气气流经过流动截面缩减段420，再由尾气出口500排出。
控制器600针对氨检测器450检测的逃逸氨气浓度、温度传感器170检测的含氨气的待处理尾气温度以及氧传感器190检测的氧含量进行分析，并反馈至气流旁通管160中气流流量的流量控制阀180和热管理装置150，实现对整个系统的控制。
处理结果：NH 3去除率99.95％，尾气NH 3浓度1.90mg/Nm 3，N 2选择性99.5％，尾气NOx浓度51.3mg/Nm 3。
实施例3
由尾气入口100导入10000ppmv含氨气的待处理尾气进入流动界面扩张段120中，其中，70％(V/V)含氨气的待处理尾气在气流分配装置130的作用下，使进入流动界面扩张段120内部的气流在流动界面扩大时均匀分配，再进入热管理装置150(外置式燃烧器)进行调节温度，待温度调节后进入氨脱除催化剂模块200进行氨脱除反应，控制温度为500℃、空速比为20000h -1，气体流速15m·s -1，催化剂为Co-Cu-Mn复合氧化物催化剂，使含氨气的待处理尾气气流中的大部分NH 3(氨气)转化为N 2(氮气)和H 2O(水)。氨脱除反应完成后的尾气气流再进入氨氧化催化剂模块300进行氨氧化反应，控制温度为 500℃、空速比为50000h -1，气体流速15m·s -1，催化剂为Pt-Pd-Ag复合氧化物催化剂，使NH 3(氨气)和N 2O(一氧化二氮)转化为NO(一氧化氮)和NO 2(二氧化氮)。氨氧化反应完成后的尾气气流再导入气流混合装置350中，与由气流旁通管160导入的30％(V/V)的含氨气的待处理尾气混合后，再导入选择性催化还原催化剂模块400进行选择性还原反应,控制温度为450℃、空速比为10000h -1，气体流速15m·s -1，催化剂为V-W-Ti复合氧化物催化剂。选择性还原反应完成后导出的尾气气流经过流动截面缩减段420，再由尾气出口500排出。
控制器600针对氨检测器450检测的逃逸氨气浓度、温度传感器170检测的含氨气的待处理尾气温度以及氧传感器190检测的氧含量进行分析，并反馈至气流旁通管160中气流流量的流量控制阀180和热管理装置150，实现对整个系统的控制。
处理结果：NH 3去除率99.95％，尾气NH 3浓度3.79mg/Nm 3，N 2选择性99.8％，尾气NOx浓度41.1mg/Nm 3。
表1 不同实施例下处理效率情况
项目 实施例1 实施例2 实施例3
含氨尾气瞬时浓度(ppmv) 2000 5000 10000
氨脱除反应温度(℃) 250 400 500
氨脱除空速比(h -1) 5000 10000 20000
氨氧化反应温度(℃) 200 400 500
氨氧化空速比(h -1) 12000 25000 50000
选择性还原反应温度(℃) 200 350 450
选择性还原空速比(h -1) 2000 5000 10000
配气比例(％) 0 15 30
尾气流速(m·s -1) 2 8 15
NH 3去除率(％) 99.9 99.95 99.95
尾气NH 3浓度(mg/Nm 3) 1.52 1.90 3.79
N 2选择性(％) 99 99.5 99.8
尾气NOx浓度(mg/Nm 3) 41.1 51.3 41.1
以上实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述实施例对本 发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可能对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的范围。

Claims (10)

  1. 一种降低尾气氨排放的集成式催化转化系统，其特征在于，该系统包括：
    尾气入口(100)，该尾气入口(100)用于导入尾气气流；
    流动界面扩张段(120)，该流动界面扩张段与尾气入口(100)连接，在所述流动界面扩张段(120)内设有使进入流动界面扩张段(120)内部的气流在流动界面扩大时能均匀分配的气流分配装置(130)；
    热管理装置(150)，该热管理装置(150)设于所述流动界面扩张段(120)的下游，用于控制从所述流动界面扩张段(120)导出的尾气气流的温度；
    氨脱除催化剂模块(200)，该氨脱除催化剂模块(200)位于所述热管理装置(150)的下游，所述氨脱除催化剂模块(200)用于在自由氧存在的条件下使所述尾气气流中的大部分NH 3转化为N 2和H 2O；
    氨氧化催化剂模块(300)，该氨氧化催化剂模块(300)位于所述氨脱除催化剂模块(200)的下游，所述氨氧化催化剂模块(300)用于使所述氨脱除催化剂模块(200)导出的尾气气流中少量的NH 3和N 2O转化为NO和NO 2；
    选择性催化还原催化剂模块(400)，该选择性催化还原催化剂模块(400)位于所述氨氧化催化剂模块(300)的下游，所述选择性催化还原催化剂模块(400)用于在NH 3存在的条件下使所述氨氧化催化剂模块(300)导出的尾气气流中的NO和NO 2转化为N 2和H 2O；以及
    尾气出口(500)，该尾气出口(500)用于排出所述选择性催化还原催化剂模块(400)导出的尾气气流；
    或者，该系统还包括气流混合装置(350)和气流旁通管(160)：
    所述气流混合装置(350)位于所述氨氧化催化剂模块(300)的下游；所述气流混合装置(350)的入口与所述氨氧化催化剂模块(300)的出口连通；所述气流混合装置(350)的出口与选择性催化还原催化剂模块(400)的入口连通；
    所述气流旁通管(160)的入口与所述流动界面扩张段连通(120)，所述气流旁通管(160)的出口与所述气流混合装置(350)的入口连通，所述气流旁通管(160)上设有控制气流旁通管中气流流量的流量控制阀(180)。
  2. 根据权利要求1所述的系统，其特征在于，所述氨脱除催化剂模块(200)是由一个 或多个包含氨脱除催化剂的颗粒床层或蜂窝型氨脱除催化剂的切块组成；所述氨氧化催化剂模块(300)是由一个或多个包含氨氧化催化剂的颗粒床层或蜂窝型氨氧化催化剂的切块组成；所述选择性催化还原催化剂模块(400)是由一个或多个包含选择性催化还原催化剂的颗粒床层或蜂窝型选择性催化还原催化剂的切块组成。
  3. 根据权利要求1所述的系统，其特征在于，所述氨脱除催化剂模块(200)的入口处设有温度传感器(170)和氧传感器(190)；所述选择性催化还原催化剂模块(400)的下游设有氨检测器(450)。
  4. 根据权利要求2所述的系统，其特征在于，该系统还包括控制器(600)，所述控制器(600)与所述热管理装置(150)电性连接，用于控制所述氨脱除催化剂模块(200)的入口处的气流温度；所述控制器(600)与所述流量控制阀(180)电性连接，用于控制所述气流旁通管(160)中气流流量。
  5. 根据权利要求1所述的系统，其特征在于，该系统还包括外壳，所述外壳的内侧壁与所述氨脱除催化剂模块(200)、所述氨氧化催化剂模块(300)和所述选择性催化还原催化剂模块(400)之间包含密封垫(210)。
  6. 根据权利要求1所述的系统，其特征在于，所述热管理装置(150)为外置式燃烧器、内置式燃烧器、电加热器、换热器或其组合；所述选择性催化还原催化剂模块(400)与所述尾气出口之间设有流动截面缩减段(420)。
  7. 一种降低尾气氨排放的方法，该方法包括：
    由尾气入口导入的含氨气的待处理尾气中，体积比为70～100％的含氨气的待处理尾气经过温度调节后进入氨脱除催化剂模块进行氨脱除反应，再进入氨氧化催化剂模块进行氨氧化反应，然后导入选择性催化还原催化剂模块进行选择性还原反应；或者，先导入气流混合装置中，与剩余的由气流旁通管中导入的含氨气的待处理尾气进行混合后，然后导入选择性催化还原催化剂模块进行选择性还原反应；其中，所述待处理尾气中氨气的时均浓度超过500ppmv和/或所述待处理尾气中氨气的入口瞬时浓度峰值超过5000ppmv。
  8. 根据权利要求7所述的方法，其特征在于，所述氨脱除反应的条件包括：反应温度为250℃～500℃，优选为350℃～450℃；氧体积浓度8-21％；空速比为5000-20000h -1，优选为8000-12000h -1；气体流速为2-15m·s -1，优选为5-10m·s -1；氨脱除催化剂为过渡金属氧化物；优选为Co-Mn复合氧化物催化剂、Cu-Mn复合氧化物催化剂、Ti-Mn复合氧化物催化剂、Zr-Mn复合氧化物催化剂、Co-Cu-Mn复合氧化物催化剂或 Co-Ti-Mn复合氧化物催化剂中的一种或几种。
  9. 根据权利要求7所述的方法，其特征在于，所述氨氧化反应的条件包括：反应温度为250℃～500℃，优选为350℃～450℃；空速比为12000-50000 h-1，优选为20000-30000 h-1；气体流速为2-15m· s-1，优选为5-10m· s-1；氨氧化催化剂为贵金属氧化物；优选为Pt-Ag复合氧化物催化剂、Pt-Pd复合氧化物催化剂、Ag-Pd复合氧化物催化剂或Pt-Pd-Ag复合氧化物催化剂中的一种或几种。
  10. 根据权利要求7所述的方法，其特征在于，所述选择性催化还原反应的条件包括：反应温度为200℃～450℃，优选为300℃～400℃；空速比为2000-10000h -1，优选为4000-6000h -1；气体流速为2-15m·s -1，优选为5-10m·s -1；选择性催化还原催化剂为V-W复合氧化物催化剂、V-Ti复合氧化物催化剂、W-Ti复合氧化物催化剂或V-W-Ti复合氧化物催化剂中的一种或几种。
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