Catalytic oxidation system for CO in steel sintering flue gas

Abstract

The invention discloses a catalytic oxidation system for CO in steel sintering flue gas. The catalytic oxidation system comprises a flue gas heater, a CO catalytic oxidation reactor and an induced draft fan, a path of purified sintering flue gas is led out from the tail end of a denitration reactor of a sintering machine and the front end of a GGH heat exchanger to the catalytic oxidation system, the sintering flue gas enters the catalytic oxidation system, sequentially passes through a flue gas heater, a CO catalytic oxidation reactor and an induced draft fan and then returns to a flue gas outlet denitration flue of the GGH heat exchanger, and catalytic oxidation is completed. Compared with the prior art, the system has the advantages that energy consumption of an existing SCR denitration system can be reduced, more energy is saved, the purposes of CO emission reduction and carbon emission reduction can be achieved, in addition, stable operation can be achieved under the condition of ultralow flue gas emission, and the system can adapt to the characteristics of large sintering flue gas fluctuation, frequent starting and stopping and high SO2 concentration in the starting and stopping stage.

Description

Technical Field

[0001] The present invention relates to the technical field of CO emission reduction in the steel industry, and in particular to a catalytic oxidation system for CO in steel sintering flue gas. Background Art

[0002] Steel sintering flue gas contains about 0.5-1.0% CO, which is discharged with the flue gas after desulfurization and denitrification, posing a difficult problem for urban air quality control.

[0003] Currently, CO emission reduction technologies in the steel industry can be categorized into three areas: source control, process reduction, and end-of-pipe treatment. Source control primarily focuses on reducing the use of high-carbon fossil fuels such as coal during the raw material stage, thereby reducing subsequent CO emissions. Process reduction primarily involves optimizing fuel combustion conditions to promote full CO combustion, thereby reducing CO emissions. Technologies such as flue gas recirculation, surface media injection, thick bed sintering, and fuel modification are used in iron ore sintering. End-of-pipe treatment, the ultimate approach to CO control, directly treats the CO component in flue gas to reduce emissions of already generated CO. Treatment routes primarily include absorption, oxidation with strong oxidants, and catalytic oxidation. While existing treatment technologies can reduce CO concentrations by approximately 20%, it remains difficult to maintain stable emission concentrations below 5000 ppm. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides

[0005] To provide a basic understanding of some aspects of the disclosed embodiments, the following is a brief summary. This summary is not intended to be a comprehensive review, identify key or essential elements, or delineate the scope of these embodiments. Its sole purpose is to present some concepts in a simplified form as a prelude to the detailed description that follows.

[0006] The present invention adopts the following technical solutions:

[0007] The present invention provides a catalytic oxidation system for CO in steel sintering flue gas, comprising:

[0008] Flue gas heater, used to increase the temperature of sintering flue gas from the SCR denitrification system;

[0009] A CO catalytic oxidation reactor is provided at the bottom layer of the denitration reactor in the SCR denitration system, and is used to catalytically oxidize the heated sintering flue gas discharged from the flue gas heater;

[0010] The induced draft fan is arranged at the output side of the CO catalytic oxidation reactor and is used to transport the sintering flue gas discharged from the CO catalytic oxidation reactor back to the GGH heat exchanger in the flue gas desulfurization system.

[0011] Furthermore, the catalytic oxidation system for CO in steel sintering flue gas also includes: a flue gas outlet pipe and a flue gas intake interface; the flue gas intake interface is arranged at the outlet end of the SCR denitrification system, one end of the flue gas outlet pipe is connected to the flue gas intake interface, and the other end is connected to the air inlet of the flue gas heater.

[0012] Furthermore, the catalytic oxidation system for CO in steel sintering flue gas also includes: a flue gas return pipe and a return flue gas interface; the return flue gas interface is arranged on the flue gas outlet denitrification flue of the GGH heat exchanger in the flue gas desulfurization system, one end of the flue gas return pipe is connected to the return flue gas interface, and the other end is connected to the air outlet of the induced draft fan.

[0013] Furthermore, a first temperature sensor is provided on the flue gas outlet pipe; a second temperature sensor and a first CO sensor are provided on the pipe connecting the flue gas heater and the CO catalytic oxidation reactor; a third temperature sensor is provided on the pipe connecting the CO catalytic oxidation reactor and the induced draft fan; and a second CO sensor, a flow meter and a pressure gauge are provided on the flue gas return pipe.

[0014] Furthermore, the catalytic oxidation system for CO in steel sintering flue gas also includes: a control module; the control module includes: a CO concentration monitoring unit, used to obtain detection data from the first CO sensor and the second CO sensor and calculate the difference to output a CO catalytic conversion rate parameter value; a temperature monitoring unit, used to obtain detection data from the first temperature sensor, the second temperature sensor and the third temperature sensor to output a flue gas temperature rise parameter value; a pressure drop and flow monitoring unit, used to obtain detection data from the flow meter and the pressure gauge to output a catalyst pressure drop parameter value.

[0015] Furthermore, the catalytic oxidation system for CO in steel sintering flue gas also includes: a manual regulating valve; the manual regulating valve is provided on the flue gas outlet pipe, the flue gas return pipe, and the pipe connecting the CO catalytic oxidation reactor with the flue gas heater and the induced draft fan.

[0016] The beneficial effects brought by the present invention are:

[0017] 1. It can be used in conjunction with the existing SCR denitrification system, which not only reduces the energy consumption of the existing SCR denitrification system and saves more energy, but also achieves the purpose of reducing CO emissions and carbon emissions;

[0018] 2. It can be used under ultra-low flue gas emission conditions (SO2≤35mg / m 3 、NO X ≤50 mg / m3 , dust ≤ 10mg / m 3 ) and can adapt to the characteristics of large fluctuations in sintering flue gas, frequent start and stop, and high SO2 concentration during the start and stop stages;

[0019] 3. It requires minimal changes to the existing SCR denitrification system and is compatible with the installation of different catalyst products in the reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 It is a schematic diagram of a catalytic oxidation system for CO in steel sintering flue gas according to the present invention. DETAILED DESCRIPTION

[0022] The following describes embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the embodiments described are only some of the embodiments of the present invention, and not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0023] like Figure 1 As shown, in some illustrative embodiments, a system for catalytic oxidation of CO in steel sintering flue gas is provided, including: a flue gas heater 100, a CO catalytic oxidation reactor 200, an induced draft fan 300, a control module, a sensor assembly, and a manual regulating valve 400.

[0024] The purified sintering flue gas is drawn from the end of the denitrification reactor of the SCR denitrification system 1 of the sintering machine and the front end of the GGH heat exchanger 2 in the flue gas desulfurization system to the catalytic oxidation system of this embodiment. After entering the catalytic oxidation system, the sintering flue gas passes through the flue gas heater 100, the CO catalytic oxidation reactor 200, and the induced draft fan 300 in sequence and then returns to the flue gas outlet denitrification flue of the GGH heat exchanger 2 to complete the catalytic oxidation.

[0025] The flue gas design parameters of the catalytic oxidation system of this embodiment are as follows:

[0026] Serial number project unit parameter Remark 1 Flue gas treatment volume <![CDATA[Nm 3 / h]]> 3000 Wet flue gas 2 Original flue gas temperature ℃ ～280 Flue gas temperature after heating ℃ ～310 3 <![CDATA[SO2 concentration]]> <![CDATA[mg / Nm 3 ]]> ≤35 4 Dust concentration <![CDATA[mg / Nm 3 ]]> ≤10 <![CDATA[mg / Nm 3 ]]> ≤20 Accident Status 5 NOx concentration <![CDATA[mg / Nm 3 ]]> ≤50 <![CDATA[mg / Nm 3 ]]> ～100 Highest value 6 CO content ppm 5000-10000 Valuation 7 <![CDATA[Oxygen content]]> ％ 13-17.5 8 Moisture content V％ ～15

[0027] The flue gas heater 100 is used to increase the temperature of the sintering flue gas from the SCR denitration system 1, that is, to heat the sintering flue gas drawn out from the SCR denitration system 1 to a suitable temperature to promote the subsequent CO catalytic oxidation reaction. An electric heater can be used.

[0028] The catalytic oxidation system of this embodiment further includes a flue gas outlet pipe 500 and a flue gas intake port 600. The flue gas intake port 600 is located at the outlet of the SCR denitration system 1. One end of the flue gas outlet pipe 500 is connected to the flue gas intake port 600, and the other end is connected to the air inlet of the flue gas heater 100. Preliminary purified sintering flue gas is drawn from the flue gas intake port 600 and transported through the flue gas outlet pipe 500 to the flue gas heater 100 for heating.

[0029] The CO catalytic oxidation reactor 200, located at the bottom layer of the denitration reactor in the SCR denitration system 1, catalytically oxidizes the heated sintering flue gas discharged from the flue gas heater 100. This fully utilizes space and ensures that the flue gas, after denitration and heating, can directly enter the CO catalytic oxidation reactor 200 for the next purification step.

[0030] The CO oxidation process releases a large amount of heat. Oxidizing 1000 ppm of CO in sintering flue gas can raise the flue gas temperature by over 7°C. Therefore, this embodiment reuses the energy released by CO catalytic oxidation by adding a CO catalytic oxidation reactor 200 to the bottom layer of the denitrification reactor to reduce the energy consumption of the SCR denitrification system 1. The hot blast furnace in the existing SCR denitrification system 1 originally required a temperature increase of approximately 30-35°C, but the introduction of the catalytic oxidation system of this embodiment only requires a temperature increase of 5-10°C. This not only reduces the carbon monoxide emission concentration of the entire sintering machine, reducing the original concentration of 6000-8000 ppm to between 2000-3000 ppm, but also achieves resource reuse and greater energy conservation. Furthermore, carbon emissions can be reduced. The hot blast furnace in the existing SCR denitrification system 1 uses blast furnace gas for heating. The introduction of the catalytic oxidation system of this embodiment reduces blast furnace gas consumption by 70-80%.

[0031] The induced draft fan 300, located at the output side of the CO catalytic oxidation reactor 200, is used to transport the sintering flue gas discharged from the CO catalytic oxidation reactor 200 back to the GGH heat exchanger 2 in the flue gas desulfurization system. The induced draft fan 300 extracts the sintering flue gas from the CO catalytic oxidation reactor 200 after catalytic oxidation and transports it back to the flue gas desulfurization system, ensuring that the purified flue gas can be smoothly returned to the main flue gas process for subsequent desulfurization treatment.

[0032] The catalytic oxidation system of this embodiment also includes: a flue gas return pipe 700 and a return flue gas interface 800. The return flue gas interface 800 is arranged on the flue gas outlet denitrification flue of the GGH heat exchanger 2 in the flue gas desulfurization system. One end of the flue gas return pipe 700 is connected to the return flue gas interface 800, and the other end is connected to the air outlet of the induced draft fan 300.

[0033] The catalytic oxidation system of this embodiment has an incoming flue gas temperature of about 280°C, a maximum temperature increase of about 30°C through the flue gas heater 100, and a CO oxidation rate of not less than 60% or a sintering flue gas temperature increase of not less than 15°C when the CO concentration in the inlet flue gas is about 5000-10000 ppm and the water content is 15 vol.%. The catalyst can stably operate in flue gas that meets ultra-low emission requirements and can adapt to the high start-stop frequency of the sintering machine system, that is, it can operate under ultra-low emission flue gas conditions (SO2 ≤ 35 mg / m 3 、NO X ≤50 mg / m 3 , dust ≤ 10mg / m 3 ) and can adapt to the characteristics of large fluctuations in sintering flue gas, frequent starts and stops, and high SO2 concentration in the start and stop stages.

[0034] The sensor component is used to monitor and control the key parameters in the system in real time and upload the detected data to the control module. It specifically includes: a first temperature sensor TT1, a second temperature sensor TT2, a third temperature sensor TT3, a first CO2 sensor AT1, a second CO2 sensor AT2, a flow meter 3 and a pressure gauge 4.

[0035] A first temperature sensor TT1 is provided on the flue gas outlet pipe 500 to monitor the initial temperature of the sintering flue gas outlet from the SCR denitration system 1 and provide reference data for subsequent flue gas heating.

[0036] A second temperature sensor TT2 and a first CO sensor AT1 are installed on the pipeline connecting the flue gas heater 100 and the CO catalytic oxidation reactor 200. The second temperature sensor TT2 monitors the flue gas temperature after being heated by the flue gas heater 100, ensuring that the flue gas reaches the appropriate temperature required for the catalytic oxidation reaction. The first CO sensor AT1 monitors the CO concentration in the flue gas before entering the CO catalytic oxidation reactor 200, providing initial concentration data for the catalytic oxidation reaction.

[0037] A third temperature sensor TT3 is provided on the pipe connecting the CO catalytic oxidation reactor 200 and the induced draft fan 300. The third temperature sensor TT3 monitors the temperature of the flue gas after the catalytic oxidation reaction, ensures that the reaction achieves the desired effect, and monitors temperature changes.

[0038] The flue gas return duct 700 is equipped with a second CO sensor AT2, a flow meter 3, and a pressure gauge 4. The second CO sensor AT2 monitors the CO concentration in the flue gas after the catalytic oxidation reaction to evaluate the effectiveness of the catalytic oxidation reaction. The flow meter 3 monitors the flow of flue gas returning to the GGH heat exchanger 2 in the flue gas desulfurization system to ensure stable flue gas flow within the system. The pressure gauge 4 monitors the pressure within the flue gas return duct.

[0039] Through the layout of multiple sensors, comprehensive monitoring of flue gas temperature, CO concentration, flow rate, and pressure is achieved, ensuring that all system operating parameters are always within controllable ranges. The real-time data provided by the sensors provides an accurate reference for the system's automated control, enabling rapid and accurate adjustments based on actual operating conditions. By monitoring key parameters, potential anomalies can be promptly identified and addressed, ensuring the safety and stability of system operations.

[0040] The control module includes: CO concentration monitoring unit, temperature monitoring unit, pressure drop and flow monitoring unit.

[0041] The CO concentration monitoring unit is used to obtain detection data from the first CO sensor AT1 and the second CO sensor AT2 and calculate the difference to output a CO catalytic conversion rate parameter value. The first CO sensor AT1 monitors the CO concentration in the flue gas before entering the CO catalytic oxidation reactor, while the second CO sensor AT2 monitors the CO concentration in the flue gas after the catalytic oxidation reaction.

[0042] The CO concentration monitoring unit compares the acquired detection data and calculates the concentration difference between the two. This output difference reflects the CO removal efficiency of the CO catalytic oxidation reactor 200. Based on this concentration difference, the CO concentration monitoring unit further calculates the CO catalytic conversion rate parameter value, a key indicator for evaluating the performance of the CO catalytic oxidation reactor, representing the percentage of CO converted to other substances (such as CO2) per unit time. The CO concentration monitoring unit outputs the calculated CO catalytic conversion rate parameter value to the PLC control system in real time, allowing operators to monitor and adjust the system operating status, thereby optimizing the catalytic oxidation reaction and improving CO removal efficiency.

[0043] The temperature monitoring unit is used to acquire detection data from the first temperature sensor TT1, the second temperature sensor TT2, and the third temperature sensor TT3, and perform corresponding data processing and analysis to output the flue gas temperature rise amplitude parameter value. The first temperature sensor TT1 monitors the initial flue gas temperature entering the flue gas heater 100; the second temperature sensor TT2 monitors the flue gas temperature after being heated by the flue gas heater 100, that is, the flue gas temperature entering the CO catalytic oxidation reactor 200; and the third temperature sensor TT3 monitors the flue gas temperature after the catalytic oxidation reaction.

[0044] The temperature monitoring unit calculates the temperature difference between the first temperature sensor TT1 and the second temperature sensor TT21 to determine the temperature rise of the flue gas after heating. It also calculates the temperature difference between the second temperature sensor TT2 and the third temperature sensor TT3 to determine the temperature rise of the flue gas after catalytic oxidation. The temperature monitoring unit performs a comprehensive analysis of the acquired temperature data, determining, for example, whether the temperature variation in the system is within a reasonable range and whether the temperature conditions required for the catalytic oxidation reaction are met. Based on the temperature rise parameter value, the PLC control system automatically adjusts parameters such as the heating power of the flue gas heater 100 and the flow rate of the induced draft fan 300 to optimize the catalytic oxidation reaction conditions and ensure stable and efficient system operation.

[0045] The pressure drop and flow monitoring unit is used to obtain detection data from flow meter 3 and pressure gauge 4 to output the catalyst pressure drop parameter value. Flow meter 3 measures the flow rate of flue gas returning from the catalytic oxidation reactor, while pressure gauge 4 monitors the pressure change of the flue gas before and after passing through the catalyst bed.

[0046] The pressure drop and flow monitoring unit receives detection data from the flow meter 3 and the pressure gauge 4 in real time. By comparing the pressure values measured by the pressure gauge 4 before and after the catalyst bed, it calculates the pressure drop of the catalyst bed, that is, the pressure loss generated when the flue gas passes through the catalyst bed. Combined with the data from the flow meter 3, the flow state of the flue gas in the system is determined to ensure that the flow rate is stable within an appropriate range to meet the needs of the catalytic oxidation reaction. The pressure drop and flow monitoring unit outputs the calculated catalyst pressure drop parameter value to the PLC control system in real time for the operator to monitor and adjust the system operating status. Based on the pressure drop parameter value, the PLC control system can automatically adjust the operating parameters of the induced draft fan to optimize the flue gas flow state, reduce the pressure drop of the catalyst bed, and improve the system operating efficiency.

[0047] Manual regulating valves 400 are installed on the flue gas outlet duct 500, the flue gas return duct 700, and the pipes connecting the CO catalytic oxidation reactor 200 with the flue gas heater 100 and the induced draft fan 300. These control the flow of the sintering flue gas from the SCR denitrification system 1 and the return flow of the flue gas to the main flue after treatment by the CO catalytic oxidation reactor 200. This controls the flow and distribution of the flue gas. By adjusting the valve opening, the pressure distribution within the pipes can be changed, helping to optimize the flow of the flue gas in the system, reduce pressure drop, and improve system operating efficiency.

[0048] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A catalytic oxidation system for CO in steel sintering flue gas, characterized in that: include: Flue gas heater, used to increase the temperature of sintering flue gas from the SCR denitrification system; A CO catalytic oxidation reactor is provided at the bottom layer of the denitration reactor in the SCR denitration system, and is used to catalytically oxidize the heated sintering flue gas discharged from the flue gas heater; The induced draft fan is arranged at the output side of the CO catalytic oxidation reactor and is used to transport the sintering flue gas discharged from the CO catalytic oxidation reactor back to the GGH heat exchanger in the flue gas desulfurization system.

2. The catalytic oxidation system for CO in steel sintering flue gas according to claim 1, characterized in that: Also includes: Flue gas outlet pipe and flue gas extraction interface; The flue gas interface is arranged at the outlet end of the SCR denitration system, one end of the flue gas outlet pipe is connected to the flue gas interface, and the other end is connected to the air inlet of the flue gas heater.

3. The catalytic oxidation system for CO in steel sintering flue gas according to claim 2, characterized in that: Also includes: Flue gas return duct and flue gas return interface; The return flue gas interface is arranged on the flue gas outlet denitrification flue of the GGH heat exchanger in the flue gas desulfurization system. One end of the flue gas return pipe is connected to the return flue gas interface, and the other end is connected to the air outlet of the induced draft fan.

4. The catalytic oxidation system for CO in steel sintering flue gas according to claim 3, characterized in that: A first temperature sensor is provided on the flue gas outlet pipe; A second temperature sensor and a first CO sensor are provided on the pipe connecting the flue gas heater and the CO catalytic oxidation reactor; A third temperature sensor is provided on the pipe connecting the CO catalytic oxidation reactor and the induced draft fan; A second CO sensor, a flow meter and a pressure gauge are provided on the flue gas return duct.

5. The catalytic oxidation system for CO in steel sintering flue gas according to claim 4, characterized in that: Also includes: Control module; The control module includes: a CO concentration monitoring unit, configured to obtain detection data from the first CO sensor and the second CO sensor and calculate a difference to output a CO catalytic conversion rate parameter value; a temperature monitoring unit, configured to obtain detection data from the first temperature sensor, the second temperature sensor, and the third temperature sensor to output a flue gas temperature rise amplitude parameter value; The pressure drop and flow monitoring unit is used to obtain the detection data of the flow meter and the pressure gauge to output the catalyst pressure drop parameter value.

6. The catalytic oxidation system for CO in steel sintering flue gas according to claim 5, characterized in that: Also includes: Manual regulating valve; the manual regulating valve is provided on the flue gas outlet pipe, the flue gas return pipe and the pipe connecting the CO catalytic oxidation reactor with the flue gas heater and the induced draft fan.

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