Determination and removal method and system for chromium in sintering flue gas

Abstract

The invention relates to the technical field of sintering flue gas detection, in particular to a method and a system for measuring and removing chromium in sintering flue gas, which comprises the following steps: preparing a mixed solution with NaOH concentration of 2-8% and KOH concentration of 1-4% as an absorption liquid by using deionized water and a superior pure medicine, adding the mixed solution into each absorption tank, connecting flue gas absorption equipment, a real-time feedback signal obtained by the air pressure sensing device in the absorption tank automatically controls the operation of the flue gas supercharging device in the flue gas outlet branch pipeline, and the automatic flow control device measures the flue gas flow in the flue gas outlet branch pipeline in real time and automatically controls the flow. A flue gas inlet branch pipeline valve and a flue gas outlet branch pipeline valve are automatically controlled through an automatic control program according to pressure and flow numerical values read by an air pressure sensing device and an automatic flow control device of each branch, and absorption liquid detection and result analysis are carried out; and it is ensured that chromium in the flue gas is more thoroughly absorbed by the absorption liquid, so that the determination result of chromium in the flue gas is more accurate.

Description

Technical Field

[0001] This invention relates to the field of sintering flue gas detection technology, and in particular to a method and system for determining and removing chromium from sintering flue gas. Background Technology

[0002] The state strictly regulates the discharge and disposal of hazardous waste, and regulations stipulate that hazardous waste must be centrally processed by qualified enterprises. According to national hazardous waste identification standards, some chromium-containing waste from steel enterprises is classified as hazardous waste, with the classification number HW17 in the national hazardous waste list. Common valence states of chromium, trivalent and hexavalent chromium, are both toxic substances, especially hexavalent chromium, which is highly toxic and classified as a carcinogen and mutagen. To treat these hazardous wastes, some steel enterprises use sintering processes to render them harmless, resulting in some chromium entering the atmosphere with the flue gas, causing serious environmental pollution. Therefore, studying the chromium content in flue gas is of great significance in controlling chromium pollution from flue gas. Typically, after dust removal, desulfurization, and denitrification processes, the chromium content in sintering flue gas is low, existing in the gaseous phase or as fine particulate matter. Currently, many methods exist for detecting chromium content in solids and liquids, such as atomic absorption spectrometry, spectrophotometry, and colorimetric methods, but research on methods for detecting chromium content in emitted flue gas is limited.

[0003] In the prior art, patent application number 202210464227.6 discloses a method for analyzing the total chromium content in sintering flue gas, which solves the problem of insufficient contact between the flue gas and the absorbent liquid, short reaction time, and poor absorption effect caused by the prior art, resulting in inaccurate content analysis. This method uses a double gas storage bag to allow the flue gas to be circulated multiple times, which can ensure that the chromium in the flue gas is completely absorbed, but it has two drawbacks: 1) Since the chromium content in sintering flue gas flues in real time and the fluctuations are drastic, this method can only absorb a small part of the sintering flue gas through multiple cycles of gas storage bags, and its detection results cannot fully represent the large flow of sintering flue gas; 2) The process of multiple cycles using a double gas storage bag takes a long time, which affects the measurement efficiency.

[0004] Patent application number 202210596994.2 discloses a system and method for detecting Cr content in sintering flue gas, which solves the problem of insufficient contact and short contact time between the flue gas to be tested and the absorbent liquid in the existing technology, resulting in inaccurate detection results. The method adopts a special absorber structure, which can achieve more thorough absorption of harmful elements in the flue gas, but still has certain drawbacks. That is, the gas to be tested moves upward from the bottom of the absorbent liquid in the form of small bubbles. Although the contact is relatively sufficient, the reaction time is short, almost instantaneous, which still cannot ensure that the chromium in the flue gas is completely absorbed, thus leading to errors in the measurement results. Summary of the Invention

[0005] This invention provides a method and system for determining and removing chromium from sintering flue gas. It ensures that the chromium in the flue gas is absorbed more thoroughly by the absorbent liquid, and achieves online removal of chromium from the flue gas while ensuring more accurate detection results. It does not affect flue gas emissions and normal production, and has the characteristics of low cost, short time consumption and high efficiency.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A method for determining and removing chromium from sintering flue gas, comprising the following steps: S1. Preparation of the absorption solution: A mixed solution of 2%–8% NaOH and 1%–4% KOH was prepared using deionized water and superior pure reagents as the absorption solution. The prepared absorption solution was then added to each absorption tank. S2, Equipment connected to flue gas absorption; S3. Chromium in flue gas is absorbed online by a flue gas absorption device; S4. Absorption solution detection and result analysis: After the online absorption of the flue gas in the test section is completed, the total flow rate of the flue gas in the entire test section is recorded by a gas flow meter and recorded as V, in L; the total volume of the absorption liquid is measured and recorded as Q, in mL; after the volume is measured, the absorption liquid is then passed into a liquid composition analysis device to determine its TCr concentration and recorded as W, in μg / mL. The chromium content X in the flue gas was calculated, with X expressed as Cr2O3, and the final result was obtained: ; X unit: μg / m 3 .

[0007] Furthermore, the equipment for connecting the flue gas absorption is specifically configured as follows: N flue gas inlet branch pipes are connected to the main flue gas inlet pipe. Each flue gas inlet branch pipe is connected to a flue gas inlet branch pipe valve and a branch pipe flue gas pressurization device. Each flue gas inlet branch pipe is connected to an absorption tank at its end. Each absorption tank is connected to an absorption tank pressure sensor and a level gauge, and also has an absorption tank inlet valve and an absorption tank outlet valve. Each absorption tank is connected to a flue gas outlet branch pipe at its other end. Each flue gas outlet branch pipe is connected to a flue gas outlet branch pipe valve and an automatic flow control device. The N flue gas outlet branch pipes converge together and are connected to the main flue gas outlet pipe.

[0008] Furthermore, the prepared absorbent solution in step S1 is added to each absorbent tank, and the liquid level of the absorbent solution is not lower than 1 / 2 of the tank height.

[0009] Furthermore, the chromium in the flue gas is absorbed online by the flue gas absorption equipment. The operation of the flue gas pressurization device in the branch pipeline is automatically controlled by the real-time feedback signal obtained from the pressure sensor in the absorption tank. The automatic flow control device measures the flue gas flow rate in the flue gas outlet branch pipeline in real time and performs automatic flow control. The automatic control program automatically controls the valves of the flue gas inlet branch pipeline and the flue gas outlet branch pipeline based on the pressure and flow rate values ​​read by the pressure sensor and automatic flow control device in each branch. Specifically, the process includes the following: S3.1, Inflation Process: The automatic valve control program keeps the inlet valve of the first flue gas inlet branch pipe open and the outlet valve closed. The inlet and outlet valves of other branch pipes are also closed. In this state, flue gas enters the corresponding absorption tank from the first flue gas inlet branch pipe. The flue gas pressurization device in the branch pipe gradually increases the pressure inside the absorption tank. The pressure sensor inside the absorption tank measures the pressure before and after pressurization in real time. The initial pressure is recorded as... When the measured air pressure reaches 50-200 kPa, the automatic control program of the valve receives the signal sent by the air pressure sensor and automatically closes the air inlet valve of the first flue gas inlet branch pipe, while opening the air inlet valve of the second flue gas inlet branch pipe to start charging the second flue gas inlet branch pipe. This completes the charging process of the first flue gas inlet branch pipe. And so on, the charging process of N flue gas inlet branch pipes is completed in sequence. After the Nth branch pipe completes the charging process, it starts to circulate from the first branch pipe again. S3.2 Oscillating Absorption Process: After the gas filling process of each flue gas inlet branch pipeline is completed, the absorption program is automatically started, and the absorption tank of that branch pipeline oscillates up and down. S3.3, Venting Process: Similar to the charging process, the venting process is controlled by an automatic valve control program. As the charging process of N flue gas inlet branch pipes proceeds sequentially, when the (N-1)th branch begins its charging process, the absorption tank oscillation system stops the oscillation of the absorption tank in the first branch. The automatic valve control program automatically opens the valve of the first flue gas outlet branch pipe and adjusts the flue gas flow rate to be the same as that of the main flue gas inlet pipe through the automatic flow control device of this branch. During this process, the pressure sensor of the absorption tank in the first branch... The device measures that when the gas pressure in the absorption tank drops to P0 again, the venting process of that branch pipeline is complete. At this time, the absorption tank oscillation system stops the oscillation of the second branch absorption tank, and the automatic valve control program automatically closes the valve of the first flue gas outlet branch pipeline and simultaneously opens the valve of the second flue gas outlet branch pipeline, starting the venting process of the second branch pipeline. This process is repeated for N flue gas inlet branch pipelines. After the Nth branch pipeline completes its venting process, it recirculates from the first branch pipeline.

[0010] Furthermore, the absorption tank undergoes reciprocating oscillation, with the tank body amplitude being 0.6 to 1 times the tank height and the vibration frequency being 120 to 180 times / min.

[0011] Furthermore, the gas flow meter is installed on the main flue gas inlet pipe.

[0012] Furthermore, the determination of the total volume of the absorbent liquid is carried out by opening the drain valves of each absorbent tank, so that all the absorbent liquid in each absorbent tank is discharged into the absorbent liquid discharge tank before measurement.

[0013] Furthermore, the range of N is: 20≤N≤60.

[0014] A system for determining and removing chromium from sintering flue gas includes an absorbent feeding-discharging system, an automatic control system for sintering flue gas absorption, and an absorber oscillation system. The absorbent feeding-discharging system includes an absorbent feed trough, absorbent discharge branch pipes, absorbent feed branch pipes, absorbent main feed pipes, absorbent main discharge pipes, absorbent volume measuring device, absorbent discharge trough, absorbent tank inlet valve, and absorbent tank outlet valve. The absorbent feed trough is connected to a longitudinal absorbent main feed pipe. The absorbent main feed pipe is connected to N parallel absorbent feed branch pipes. Each absorbent feed branch pipe is connected to an absorbent tank through an absorbent tank inlet valve. Each absorbent tank outlet valve is connected to an absorbent discharge branch pipe. The N absorbent discharge branch pipes are connected in parallel to a main absorbent discharge pipe. The other end of the main absorbent discharge pipe is connected to an absorbent discharge trough equipped with an absorbent volume measuring device. The sintering flue gas absorption automatic control system includes a main flue gas inlet pipeline, flue gas inlet branch pipeline valves, branch pipeline flue gas pressurization devices, an absorption tank pressure sensor, an absorption tank level gauge, an absorption tank, flue gas outlet branch pipeline valves, an automatic flow control device, a main flue gas outlet pipeline, flue gas inlet branch pipelines, flue gas outlet branch pipelines, and a gas flow meter. The main flue gas inlet pipeline equipped with the gas flow meter connects to N parallel flue gas inlet branch pipelines. Each flue gas inlet branch pipeline is equipped with a flue gas inlet branch pipeline valve and a branch pipeline flue gas pressurization device. The other end of each flue gas inlet branch pipe is connected to the top of an absorption tank. Each absorption tank is equipped with an absorption tank pressure sensor and an absorption tank level gauge, and is externally connected to an absorption tank drain valve and an absorption tank inlet valve. Each absorption tank is also connected to the top of a flue gas outlet branch pipe. Each flue gas outlet branch pipe has an automatic flow control device at one end near the absorption tank and a flue gas outlet branch pipe valve at the other end. N flue gas outlet branch pipes are connected in parallel to the main flue gas outlet pipe. The absorption tank oscillation system includes an absorption tank oscillation device mounting frame and an absorption tank oscillation cantilever. The absorption tank oscillation device mounting frame connects N longitudinally arranged absorption tank oscillation cantilever arms. The absorption tank oscillation cantilever arms are connected to the absorption tank oscillation device mounting frame by a sliding track. Each absorption tank can independently reciprocate in the vertical direction. Each absorption tank oscillation cantilever arm is connected to an absorption tank.

[0015] Furthermore, the absorbent feeding-discharging system, the absorbent tank pressure sensor, and the absorbent tank level gauge are made of acid and alkali resistant materials. The absorption tank, flue gas inlet branch pipe and flue gas outlet branch pipe are made of explosion-proof material; The ends of the flue gas inlet branch pipe and the flue gas outlet branch pipe that connect to the absorption tank are made of non-rigid flexible hoses.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1) Using multiple parallel absorption tanks to absorb chromium in flue gas can significantly increase the contact area between flue gas and absorption liquid, thereby improving the absorption efficiency of chromium in sintering flue gas. More importantly, by controlling the filling and venting of N flue gas branches through an automatic control program, the gas reaction time in the absorption tank is maximized while ensuring a continuous and stable output flue gas flow rate. The total reaction time is more than 20 times longer than that of traditional absorption methods. 2) By pressurizing the flue gas, the reaction efficiency of the gas and liquid in the absorption tank is significantly improved, more than 10 times higher than that under conventional gas pressure. 3) The use of oscillation in the absorption tank provides the reaction kinetics conditions for the chemical reaction between the flue gas and the absorbent liquid, further promoting the reaction to proceed faster and improving the reaction efficiency of the flue gas and the absorbent liquid; 4) It solves the problems of low accuracy, complex operation, long time consumption and high cost of existing methods. It also solves the problem of inaccurate detection results caused by incomplete absorption of the target elements in the flue gas when using conventional chemical methods to determine the composition of flue gas, as well as the problem of not being able to achieve online measurement of large flow flue gas and the long process time. 5) It ensures that the chromium in the flue gas is absorbed more thoroughly by the absorbent, thus making the measurement results of chromium in the flue gas more accurate. It can also realize online detection without affecting the flue gas output and normal production, and has the characteristics of low cost, short time consumption and high efficiency. 6) This invention achieves the effective removal of chromium from flue gas while accurately measuring it, thus playing a positive role in reducing the concentration of particulate matter in sintering flue gas and reducing the emission of harmful elements. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the absorbent liquid feeding-discharging system described in this invention.

[0018] Figure 2 This is a schematic diagram of the sintering flue gas absorption automatic control system described in this invention.

[0019] Figure 3 This is a schematic diagram of the structure of the absorption tank oscillation system described in this invention.

[0020] In the diagram: 1. Absorbent feed trough; 2. Absorbent discharge branch pipe; 3. Absorbent feed branch pipe; 4. Absorbent feed main pipe; 5. Absorbent discharge main pipe; 6. Absorbent volume measuring device; 7. Absorbent discharge trough; 8. Absorbent tank inlet valve; 9. Absorbent tank drain valve; 10. Flue gas inlet main pipe; 11. Flue gas inlet branch pipe valve; 12. Branch pipe flue gas pressurization device; 13. Absorbent tank pressure sensor; 14. Absorbent tank level gauge; 15. Absorbent tank; 16. Automatic flow control device; 17. Flue gas outlet branch pipe valve; 18. Flue gas outlet main pipe; 19. Flue gas inlet branch pipe; 20. Flue gas outlet branch pipe; 21. Gas flow meter; 22. Absorbent tank oscillation device mounting frame; 23. Absorbent tank oscillation cantilever. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: This invention discloses a method for determining and removing chromium from sintering flue gas. Its purpose is to address the problem that existing detection methods cannot completely absorb trace or micro-elements in flue gas, thus hindering accurate determination of their content. This system and method effectively maximize the absorption rate of trace or micro-chromium in flue gas, ensuring more accurate detection results. The method includes the following steps: S1. Preparation of the absorption solution: A mixed solution of 2%–8% NaOH and 1%–4% KOH was prepared using deionized water and high-purity reagents as the absorbent. (See [link to absorbent solution]). Figure 1 The absorbent feeding-discharging system adds the prepared absorbent to each absorbent tank 15, and controls the absorbent level to reach about 1 / 2 of the tank height by means of the absorbent level gauge 14.

[0022] S2, Connect to the flue gas absorption system: N flue gas inlet branch pipes 19 are connected to the main flue gas inlet pipe 10, where 20≤N≤60. Each flue gas inlet branch pipe 19 is connected to a flue gas inlet branch pipe valve 11 and a branch pipe flue gas booster device 12. Each flue gas inlet branch pipe 19 is connected to an absorption tank 15 at its end. Each absorption tank 15 contains an absorption tank pressure sensor 13 and a level gauge, as well as an absorption tank inlet valve 8 and an absorption tank outlet valve 9. The other end of each absorption tank 15 is connected to a flue gas outlet branch pipe 20. Each flue gas outlet branch pipe 20 is connected to a flue gas outlet branch pipe valve 17 and an automatic flow control device 16. The N flue gas outlet branch pipes 20 converge and connect to the main flue gas outlet pipe 18. (See...) Figure 2 .

[0023] S3. Online absorption of chromium in flue gas: The online absorption of chromium in the flue gas is achieved through an automatic control system for sintering flue gas absorption. This system automatically controls the operation of the flue gas pressurization device 12 in the branch pipeline based on real-time feedback signals obtained from the pressure sensor in the absorption tank 15. Furthermore, the automatic flow control device 16 in this control system can measure the flue gas flow rate in the flue gas outlet branch pipeline 20 in real time and achieve automatic and precise flow control. The system includes N parallel flue gas branch pipelines, each with its own inlet and outlet valves. The opening and closing of the inlet and outlet valves are precisely controlled through a specific automatic valve control program. The operation of this automatic control program is achieved by reading the pressure and flow rates from the pressure sensor and the automatic flow control device 16 in each branch. The specific absorption steps are as follows: S3.1, Inflation Process: The automatic valve control program keeps the inlet valve of the first flue gas inlet branch pipe 19 open and the outlet valve closed. The inlet and outlet valves of other branch pipes are also closed. In this state, flue gas enters the corresponding absorption tank 15 from the first flue gas inlet branch pipe 19. The flue gas pressurization device gradually increases the pressure inside the absorption tank 15. The pressure sensor inside the absorption tank 15 measures the pressure before and after pressurization in real time, with the initial pressure recorded as P0. When the measured pressure reaches 50–200 kPa, the valve… The automatic control program of the door receives a signal from the air pressure sensor and automatically closes the air inlet valve of the first flue gas inlet branch pipe 19. At the same time, it opens the air inlet valve of the second flue gas inlet branch pipe 19 and begins to fill the second flue gas inlet branch with air. This completes the filling process of the first flue gas inlet branch pipe 19. This process is repeated for N flue gas inlet branch pipes 19. After the Nth branch pipe has completed its filling process, it starts to circulate again from the first branch pipe. In the actual online absorption process, the amount of flue gas needs to be considered to determine the value of N. To ensure the absorption effect, the minimum value of N is 20.

[0024] S3.2 Oscillating Absorption Process: The absorption of chromium in flue gas is achieved by the oscillation system of the absorption tank. After the gas filling process of each flue gas inlet branch pipe 19 is completed, the absorption program is automatically started, and the absorption tank 15 of the branch is oscillated up and down. The amplitude of the absorption tank body is 0.6 to 1 times the height of the tank body, and the vibration frequency is 120 to 180 times / min.

[0025] S3.3, Venting Process: Similar to the charging process, the venting process is controlled by an automatic valve control program. As the charging process of the N flue gas inlet branch pipes 19 proceeds sequentially, when the (N-1)th branch begins its charging process, the absorption tank oscillation system stops the oscillation of the absorption tank 15 of the first branch. The automatic valve control program automatically opens the valve 17 of the first flue gas outlet branch pipe and adjusts the flue gas flow rate to be the same as that of the main flue gas inlet pipe 10 through the automatic flow control device 16 of this branch. During this process, the pressure sensor of the absorption tank of the first branch... Measurements are taken at position 13. When the gas pressure in the absorption tank drops to P0 again, the venting process of that branch pipeline is completed. At this time, the absorption tank oscillation system stops the oscillation of the second branch absorption tank 15, and the valve automatic control program automatically closes the valve 17 of the first flue gas outlet branch pipeline. At the same time, it automatically opens the valve 17 of the second flue gas outlet branch pipeline, and begins the venting process of the second branch pipeline. This process is repeated for N flue gas inlet branch pipelines 19. After the Nth branch pipeline completes the venting process, it recirculates from the first branch pipeline.

[0026] S4. Absorption solution detection and result analysis: After the online absorption of the flue gas in the test section is completed, the total flow rate of the flue gas in the entire test section is recorded by the gas flow meter 21 of the main flue gas inlet pipe 10, denoted as V, in L; at the same time, the drain valves 9 of each absorption tank are opened through the absorbent feeding-discharging system, so that all the absorbent in each absorption tank 15 is discharged into the absorbent discharge tank 7. The total volume of the absorbent is measured by the absorbent volume measuring device 6, denoted as Q, in mL; after the volume is measured, the absorbent is then passed into the liquid composition analysis equipment to measure its TCr concentration, denoted as W, in μg / mL; By substituting the measured data V, Q, and W into the following formula, the chromium content X in the flue gas (calculated as Cr2O3) is calculated to obtain the final result: ; X unit: μg / m 3 .

[0027] The above methods rely on the following three systems: the absorbent feeding-discharging system, the sintering flue gas absorption automatic control system, and the absorber oscillation system; (a) Absorbent liquid feeding-discharging system; See Figure 1 The absorbent feeding-discharging system includes an absorbent feed tank 1, an absorbent discharge branch pipe 2, an absorbent feed branch pipe 3, an absorbent feed main pipe 4, an absorbent discharge main pipe 5, an absorbent volume measuring device 6, an absorbent discharge tank 7, an absorbent tank inlet valve 8, and an absorbent tank drain valve 9. The absorbent feed tank 1 is connected to a longitudinal absorbent feed main pipe 4. The absorbent feed main pipe 4 is connected to N parallel absorbent feed branch pipes 3. Each absorbent feed branch pipe 3 is connected to an absorbent tank 15 through an absorbent tank inlet valve 8. Each absorbent tank 15 has an absorbent tank drain valve 9 connected to an absorbent discharge branch pipe 2. The N absorbent discharge branch pipes 2 are connected in parallel to an absorbent discharge main pipe 5. The other end of the absorbent discharge main pipe 5 is connected to an absorbent discharge tank 7 equipped with an absorbent volume measuring device 6.

[0028] (ii) Automatic control system for sintering flue gas absorption; See Figure 2The sintering flue gas absorption automatic control system includes a main flue gas inlet pipe 10, flue gas inlet branch pipe valves 11, branch pipe flue gas booster devices 12, absorption tank pressure sensor 13, absorption tank level gauge 14, absorption tank 15, flue gas outlet branch pipe valves 17, flow automatic control device 16, flue gas outlet main pipe 18, flue gas inlet branch pipes 19, flue gas outlet branch pipes 20, and a gas flow meter 21. The main flue gas inlet pipe 10 with the gas flow meter 21 connects to N parallel flue gas inlet branch pipes 19. Each flue gas inlet branch pipe 19 is equipped with a flue gas inlet branch pipe valve 11 and a branch pipe flue gas booster device 12. 2. The other end of each flue gas inlet branch pipe 19 is connected to the top of an absorption tank 15. Each absorption tank 15 is connected to an absorption tank pressure sensor 13 and an absorption tank level gauge 14, and is externally connected to an absorption tank drain valve 9 and an absorption tank inlet valve 8. The top of each absorption tank 15 is also connected to a flue gas outlet branch pipe 20. Each flue gas outlet branch pipe 20 has an automatic flow control device 16 at one end near the absorption tank 15 and a flue gas outlet branch pipe valve 17 at the other end. N flue gas outlet branch pipes 20 are connected in parallel to the main flue gas outlet pipe 18.

[0029] (iii) Absorption tank oscillation system; See Figure 3 The absorption tank oscillation system includes an absorption tank oscillation device fixing frame 22 and an absorption tank oscillation cantilever 23. The absorption tank oscillation device fixing frame 22 connects N longitudinally arranged absorption tank oscillation cantilever 23. The absorption tank oscillation cantilever 23 and the absorption tank oscillation device fixing frame 22 are connected by a slide rail, which can ensure that each absorption tank 15 can move independently in the vertical direction. Each absorption tank oscillation cantilever 23 is connected to an absorption tank 15.

[0030] The entire absorbent feeding-discharging system, the absorbent tank pressure sensor 13, and the absorbent tank level gauge 14 are made of acid and alkali resistant materials.

[0031] The absorption tank 15, the flue gas inlet branch pipe 19, and the flue gas outlet branch pipe 20 are made of explosion-proof materials.

[0032] The ends of the flue gas inlet branch pipe 19 and flue gas outlet branch pipe 20 that connect to the absorption tank 15 are made of non-rigid flexible hoses to ensure that the absorption tank 15 vibrates without obstruction.

[0033] The gas flow meter 21 can detect the instantaneous flow rate of flue gas in real time, and it can also detect the cumulative total flow rate of a certain section of flue gas.

[0034] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0035] Example 1 A mixed solution of 2% NaOH and 1% KOH was prepared using deionized water and high-purity reagents as the absorbent. (See attached image) Figure 1 The absorbent feeding-discharging system adds the prepared absorbent to each absorbent tank 15, and controls the absorbent level to reach about 1 / 2 of the tank height by means of the absorbent level gauge 14.

[0036] Twenty flue gas inlet branch pipes 19 are connected to the main flue gas inlet pipe 10, see Figure 2 Connect to the automatic control system for sintering flue gas absorption.

[0037] The automatic control program of the valve is activated, and the initial air pressure is recorded as P0. The air pressure condition for automatic valve switching is set to 50 kPa. The inflation process is started, and the absorption tank vibration system is activated. The amplitude of the absorption tank body is set to 0.6 times the height of the tank body, and the vibration frequency is 180 times / min.

[0038] After the flue gas in the test section has been fully charged, oscillated, and vented, the total flow rate V of the flue gas in the entire test section is recorded by the gas flow meter 21 in the main flue gas inlet pipe 10, which is 19271.5 L. Simultaneously, the drain valves 9 of each absorber tank are opened through the absorbent feeding-discharging system, allowing all the absorbent in each absorber tank 15 to be discharged into the absorbent discharge trough 7. The total volume Q of the absorbent is measured using the absorbent volume measuring device 6, which is 30783.4 mL. After volume measurement, the absorbent is then passed through an ICP-MS system to determine its total chromium concentration W, which is 0.015 μg / mL. The calculated Cr2O3 content X is 35.02 μg / mL. 3 .

[0039] Example 2 A mixed solution of 8% NaOH and 4% KOH was prepared using deionized water and high-purity reagents as the absorbent. (See attached image) Figure 1 The absorbent feeding-discharging system adds the prepared absorbent to each absorbent tank 15, and controls the absorbent level to reach about 1 / 2 of the tank height by means of the absorbent level gauge 14.

[0040] Connect 60 flue gas inlet branch pipes 19 to the main flue gas inlet pipe 10, see Figure 2 Connect to the automatic control system for sintering flue gas absorption.

[0041] Start the automatic valve control program and record the initial air pressure as P0. Set the air pressure condition for automatic valve switching to 200 kPa, start the inflation process, and start the absorption tank oscillation system. Set the absorption tank body amplitude to 1 times the tank height and the vibration frequency to 120 times / min.

[0042] After the flue gas in the test section has been fully charged, oscillated, and vented, the total flow rate V of the flue gas in the entire test section is recorded by the gas flow meter 21 in the main flue gas inlet pipe 10, which is 58454.7 L. Simultaneously, the drain valves 9 of each absorber tank are opened through the absorbent feeding-discharging system, allowing all the absorbent in each absorber tank 15 to be discharged into the absorbent discharge trough 7. The total volume Q of the absorbent is measured using the absorbent volume measuring device 6, which is 93252.6 mL. After volume measurement, the absorbent is then passed through an ICP-MS system to determine its total chromium concentration W, which is 0.020 μg / mL. The calculated chromium content X is 46.62 μg / mL. 3 .

[0043] Example 3 A mixed solution of 5% NaOH and 2.5% KOH was prepared using deionized water and high-purity reagents as the absorbent. (See attached image) Figure 1 The absorbent feeding-discharging system adds the prepared absorbent to each absorbent tank 15, and controls the absorbent level to reach about 1 / 2 of the tank height by means of the absorbent level gauge 14.

[0044] Forty flue gas inlet branch pipes 19 are connected to the main flue gas inlet pipe 10, see Figure 2 Connect to the automatic control system for sintering flue gas absorption.

[0045] Start the automatic valve control program and record the initial air pressure as P0. Set the air pressure condition for automatic valve switching to 135 kPa, start the inflation process, and start the absorption tank oscillation system. Set the absorption tank body amplitude to 0.8 times the tank height and the vibration frequency to 150 times / min.

[0046] After the flue gas in the test section has been fully charged, oscillated, and vented, the total flow rate V of the flue gas in the entire test section is recorded by the gas flow meter 21 of the main flue gas inlet pipe 10, which is 40944.8 L. Simultaneously, the drain valves 9 of each absorber tank are opened through the absorbent feeding-discharging system, allowing all the absorbent in each absorber tank 15 to be discharged into the absorbent discharge trough 7. The total volume Q of the absorbent is measured using the absorbent volume measuring device 6, which is 60243.8 mL. After volume measurement, the absorbent is then passed through an ICP-MS system to determine its total chromium concentration W, which is 0.018 μg / mL. The calculated chromium content X is 38.70 μg / mL. 3 .

Claims

1. A method for determining and removing chromium from sintering flue gas, characterized in that, Includes the following steps: S1. Preparation of the absorption solution: A mixed solution of 2%–8% NaOH and 1%–4% KOH was prepared using deionized water and superior pure reagents as the absorption solution. The prepared absorption solution was then added to each absorption tank. S2, Equipment connected to flue gas absorption; S3. Chromium in flue gas is absorbed online by a flue gas absorption device; S4. Absorption solution detection and result analysis: After the online absorption of the flue gas in the test section is completed, the total flow rate of the flue gas in the entire test section is recorded by a gas flow meter and denoted as V, in L; the total volume of the absorption liquid is measured and denoted as Q, in mL. After measuring the volume, the absorption liquid is then passed into a liquid composition analysis device to determine its TCr concentration, which is recorded as W, in μg / mL. The chromium content X in the flue gas was calculated, with X expressed as Cr2O3, and the final result was obtained: ； X unit: μg / m 3 .

2. The method for determining and removing chromium from sintering flue gas according to claim 1, characterized in that, The equipment for connecting flue gas absorption is specifically configured as follows: N flue gas inlet branch pipes are connected to the main flue gas inlet pipe. Each flue gas inlet branch pipe is connected to a flue gas inlet branch pipe valve and a branch pipe flue gas pressurization device. Each flue gas inlet branch pipe is connected to an absorption tank at its end. Each absorption tank is connected to an absorption tank pressure sensor and a level gauge, and also has an absorption tank inlet valve and an absorption tank outlet valve. The other end of each absorption tank is connected to a flue gas outlet branch pipe. Each flue gas outlet branch pipe is connected to a flue gas outlet branch pipe valve and an automatic flow control device. The N flue gas outlet branch pipes converge together and are connected to the main flue gas outlet pipe.

3. The method for determining and removing chromium from sintering flue gas according to claim 1, characterized in that, The prepared absorbent solution in step S1 is added to each absorbent tank, and the liquid level of the absorbent solution is not lower than 1 / 2 of the height of the tank.

4. The method for determining and removing chromium from sintering flue gas according to claim 2, characterized in that, The chromium in the flue gas is absorbed online by the flue gas absorption equipment. The operation of the flue gas pressurization device in the branch pipeline is automatically controlled by the real-time feedback signal obtained from the pressure sensor in the absorption tank. The automatic flow control device measures the flue gas flow rate in the flue gas outlet branch pipeline in real time and automatically controls the flow rate. The automatic control program automatically controls the valves of the flue gas inlet branch pipeline and the flue gas outlet branch pipeline based on the pressure and flow rate values ​​read by the pressure sensor and the automatic flow control device in each branch. Specifically, the process includes the following: S3.1, Inflation Process: The automatic valve control program keeps the inlet valve of the first flue gas inlet branch pipe open and the outlet valve closed. The inlet and outlet valves of other branch pipes are also closed. In this state, flue gas enters the corresponding absorption tank from the first flue gas inlet branch pipe. The flue gas pressurization device in the branch pipe gradually increases the pressure inside the absorption tank. The pressure sensor inside the absorption tank measures the pressure before and after pressurization in real time. The initial pressure is recorded as... When the measured air pressure reaches 50-200 kPa, the automatic control program of the valve receives the signal sent by the air pressure sensor and automatically closes the air inlet valve of the first flue gas inlet branch pipe, while opening the air inlet valve of the second flue gas inlet branch pipe to start charging the second flue gas inlet branch pipe. This completes the charging process of the first flue gas inlet branch pipe. And so on, the charging process of N flue gas inlet branch pipes is completed in sequence. After the Nth branch pipe completes the charging process, it starts to circulate from the first branch pipe again. S3.2 Oscillating Absorption Process: After the gas filling process of each flue gas inlet branch pipeline is completed, the absorption program is automatically started, and the absorption tank of that branch pipeline oscillates up and down. S3.3, Venting Process: Similar to the charging process, the venting process is controlled by an automatic valve control program. As the charging process of N flue gas inlet branch pipes proceeds sequentially, when the (N-1)th branch begins its charging process, the absorption tank oscillation system stops the oscillation of the absorption tank in the first branch. The automatic valve control program automatically opens the valve of the first flue gas outlet branch pipe and adjusts the flue gas flow rate to be the same as that of the main flue gas inlet pipe through the automatic flow control device of this branch. During this process, the pressure sensor of the absorption tank in the first branch... The device measures that when the gas pressure in the absorption tank drops to P0 again, the venting process of that branch pipeline is complete. At this time, the absorption tank oscillation system stops the oscillation of the second branch absorption tank, and the automatic valve control program automatically closes the valve of the first flue gas outlet branch pipeline and simultaneously opens the valve of the second flue gas outlet branch pipeline, starting the venting process of the second branch pipeline. This process is repeated for N flue gas inlet branch pipelines. After the Nth branch pipeline completes its venting process, it recirculates from the first branch pipeline.

5. The method for determining and removing chromium from sintering flue gas according to claim 4, characterized in that, The absorption tank undergoes reciprocating oscillations, with the tank body amplitude being 0.6 to 1 times the tank height and the vibration frequency being 120 to 180 times / min.

6. The method for determining and removing chromium from sintering flue gas according to claim 4, characterized in that, The gas flow meter is installed on the main flue gas inlet pipe.

7. The method for determining and removing chromium from sintering flue gas according to claim 4, characterized in that, The total volume of the absorbent is determined by opening the drain valves of each absorbent tank, allowing all the absorbent in each absorbent tank to be discharged into the absorbent discharge trough before measurement.

8. The method for determining and removing chromium from sintering flue gas according to claim 1, characterized in that, The range of N is: 20≤N≤60.

9. A system for determining and removing chromium from sintering flue gas according to any one of claims 1 to 8, characterized in that, This includes the absorbent feeding-discharging system, the sintering flue gas absorption automatic control system, and the absorber oscillation system; The absorbent feeding-discharging system includes an absorbent feed trough, absorbent discharge branch pipes, absorbent feed branch pipes, absorbent main feed pipes, absorbent main discharge pipes, absorbent volume measuring device, absorbent discharge trough, absorbent tank inlet valve, and absorbent tank outlet valve. The absorbent feed trough is connected to a longitudinal absorbent main feed pipe. The absorbent main feed pipe is connected to N parallel absorbent feed branch pipes. Each absorbent feed branch pipe is connected to an absorbent tank through an absorbent tank inlet valve. Each absorbent tank outlet valve is connected to an absorbent discharge branch pipe. The N absorbent discharge branch pipes are connected in parallel to a main absorbent discharge pipe. The other end of the main absorbent discharge pipe is connected to an absorbent discharge trough equipped with an absorbent volume measuring device. The sintering flue gas absorption automatic control system includes a main flue gas inlet pipeline, flue gas inlet branch pipeline valves, branch pipeline flue gas pressurization devices, an absorption tank pressure sensor, an absorption tank level gauge, an absorption tank, flue gas outlet branch pipeline valves, an automatic flow control device, a main flue gas outlet pipeline, flue gas inlet branch pipelines, flue gas outlet branch pipelines, and a gas flow meter. The main flue gas inlet pipeline equipped with the gas flow meter connects to N parallel flue gas inlet branch pipelines. Each flue gas inlet branch pipeline is equipped with a flue gas inlet branch pipeline valve and a branch pipeline flue gas pressurization device. The other end of each flue gas inlet branch pipe is connected to the top of an absorption tank. Each absorption tank is equipped with an absorption tank pressure sensor and an absorption tank level gauge, and is externally connected to an absorption tank drain valve and an absorption tank inlet valve. Each absorption tank is also connected to the top of a flue gas outlet branch pipe. Each flue gas outlet branch pipe has an automatic flow control device at one end near the absorption tank and a flue gas outlet branch pipe valve at the other end. N flue gas outlet branch pipes are connected in parallel to the main flue gas outlet pipe. The absorption tank oscillation system includes an absorption tank oscillation device mounting frame and an absorption tank oscillation cantilever. The absorption tank oscillation device mounting frame connects N longitudinally arranged absorption tank oscillation cantilever arms. The absorption tank oscillation cantilever arms are connected to the absorption tank oscillation device mounting frame by a sliding track. Each absorption tank can independently reciprocate in the vertical direction. Each absorption tank oscillation cantilever arm is connected to an absorption tank.

10. The system for determining and removing chromium from sintering flue gas according to claim 9, characterized in that, The absorbent feeding-discharging system, the absorbent tank pressure sensor, and the absorbent tank level gauge are made of acid and alkali resistant materials. The absorption tank, flue gas inlet branch pipe and flue gas outlet branch pipe are made of explosion-proof material; The ends of the flue gas inlet branch pipe and the flue gas outlet branch pipe that connect to the absorption tank are made of non-rigid flexible hoses.

Images