Device and method for detecting hydrogen chloride in blast furnace gas

Abstract

The application relates to a device and a method for detecting hydrogen chloride in blast furnace gas, which comprises a large-diameter ball valve pipeline, a variable-diameter pipeline, a small-diameter needle valve pipeline, a multi-stage absorption device and a wet gas flowmeter. Through cooperation of the device and specific step and parameter setting, the content of chlorine in the blast furnace gas can be determined quickly, efficiently and effectively.

Description

Technical Field

[0001] This invention relates to the field of industrial environmental protection technology, specifically to an apparatus and method for detecting hydrogen chloride in blast furnace gas. Background Technology

[0002] With the continuous development of steel enterprises, more and more technologies such as oxygen-enriched pulverized coal injection and CaCl2 solution spraying for sintering are being widely used to enhance the blast furnace smelting intensity and reduce the blast furnace smelting cost. As a result, the content of acidic gases (HCl, HF, etc.) in blast furnace gas is also getting higher and higher.

[0003] However, due to the widespread adoption of dry dust removal systems for blast furnace gas in large blast furnaces, the initial design lacked consideration of the hazards of HCl gas and other acidic gases in the gas. As a result, many steel plants have experienced varying degrees of corrosion in their gas pipeline systems and scaling on the blades of their TRT (blast furnace gas residual pressure turbine power generation units) during operation, leading to significant economic losses for the steel plants.

[0004] Currently, domestic and international technologies for dechlorination of blast furnace gas are mainly divided into two categories: wet dechlorination and dry dechlorination. Wet dechlorination processes directly remove hydrogen chloride from the gas using water injection, corrosion inhibitors, and alkaline neutralizing agents. Dry dechlorination processes, on the other hand, utilize solid or powdered dechlorinating agents to chemically react with the hydrogen chloride in the gas, fixing the gaseous chlorine onto the dechlorinating agent, thereby achieving dechlorination.

[0005] Based on the current operational conditions of industrial enterprises, both of the aforementioned blast furnace gas dechlorination processes can achieve the removal objective to a certain extent. However, the exact amount of hydrogen chloride in the blast furnace gas, the remaining amount of chlorine after dechlorination, and the removal rate remain technically unknown. This results in the lack of an effective evaluation standard for dechlorination processes.

[0006] Currently, there is no corresponding detection standard for hydrogen chloride in blast furnace gas. Referring to other detection methods for hydrogen chloride, there are two main categories: (1) Fourier transform infrared spectroscopy (FTIR). This method determines the concentration of HCl in the gas by analyzing the absorption peaks of the analyte. However, this method is affected by the detection pressure and can only be performed after TRT. For blast furnace gas, a specific gas, it is a low-temperature and high-humidity gas after TRT. During sampling, HCl is easily soluble in water, resulting in low measurement results or even failure to detect it. (2) In-situ laser measurement. This method measures the attenuation of a laser beam with a specific absorption line as it passes through the gas being measured. Based on the proportional relationship between laser intensity attenuation and the content of the gas being measured, the concentration of the gas being measured is obtained. Currently, this method is greatly affected by background gas cross-interference and dust during the detection process, resulting in low detection results or even failure to detect it when used for blast furnace gas.

[0007] Chinese invention patent publication CN104569092B discloses a method and apparatus for detecting the chlorine content in blast furnace gas. The method involves contacting a specific amount of blast furnace gas with barium hydroxide and mixing it with chloride ions via electrodes to measure the chlorine content. However, the measuring device is relatively expensive and cannot eliminate other influencing elements in the blast furnace gas during chloride ion detection. Summary of the Invention

[0008] To address the aforementioned problem of detecting hydrogen chloride content in blast furnace gas, this invention utilizes the environmental atmosphere and physicochemical properties of the substance being detected, employing the most basic solution absorption method. Through extensive experimentation, a complete method and apparatus for detecting hydrogen chloride in blast furnace gas has been developed. This method overcomes the problems of hydrogen chloride's high solubility in water and background gas interference in in-situ laser measurement during Fourier transform infrared spectroscopy sampling, and is simple to operate.

[0009] Specifically, this is achieved through the following technical solution:

[0010] An apparatus for detecting hydrogen chloride in blast furnace gas includes a large-diameter ball valve pipeline, a reducing pipeline, a small-diameter needle valve pipeline, a multi-stage absorption device, and a wet gas flow meter.

[0011] One end of the large-diameter ball valve pipeline is connected to the main clean gas pipeline, and the other end is connected to the reducing pipeline. A large-diameter ball valve is installed on the large-diameter ball valve pipeline. The inlet end of the small-diameter needle valve pipeline is connected to the reducing pipeline, and the outlet end is connected to the gas inlet end of the multi-stage absorption device. A small-diameter needle valve is installed on the small-diameter needle valve pipeline. The inlet diameter of the reducing pipeline matches the diameter of the large-diameter ball valve pipeline, and the outlet diameter of the reducing pipeline matches the diameter of the small-diameter needle valve pipeline.

[0012] The inlet of the wet gas flow meter is connected to the gas outlet of the multi-stage absorption device.

[0013] The multi-stage absorption device includes a coolant carrying tank, coolant (coolant temperature below 10℃), and multiple absorption components. The coolant carrying tank is filled with coolant, and the multiple absorption components are connected in series within the coolant carrying tank. Each absorption component includes an absorption component shell, a liquid inlet, a drain outlet, an air inlet hose, a microporous aeration disc, and an exhaust outlet. The liquid inlet is located on the upper side wall of the absorption component shell, the drain outlet is located at the bottom of the absorption component shell, the bottom end of the air inlet hose extends into the inner bottom of the absorption component shell, and a microporous aeration disc is provided at the bottom end of the air inlet hose. An exhaust outlet is provided at the inner top of the absorption component shell, and the absorption component shell is filled with absorbent liquid. The inlet ends of the air inlet hoses of the multiple absorption components connected in series are connected to the exhaust outlet of the previous absorption component. The air inlet hose of the first absorption component is connected to the gas inlet end of the multi-stage absorption device, and the exhaust outlet of the last absorption component is connected to the gas outlet of the multi-stage absorption device.

[0014] Preferably, the connection point between the large-diameter ball valve pipeline and the main clean gas pipeline is located after the bag filter of the main clean gas pipeline and before the TRT device.

[0015] Preferably, the large-diameter ball valve is a DN15 ball valve; the small-diameter needle valve is a DN8 needle valve.

[0016] Preferably, the pore size of the microporous aeration disc is 1.8–2.5 mm.

[0017] As a preferred option, thermal insulation coating is provided on large-diameter ball valve pipes, reducing pipes, and small-diameter needle valve pipes.

[0018] A method for detecting hydrogen chloride in blast furnace gas, the method employing the aforementioned apparatus for detecting hydrogen chloride in blast furnace gas, comprising the following steps:

[0019] (1) Deionized water is discharged through the liquid inlet of the absorption component to clean the outer shell of the absorption component. The cleaned water is discharged through the drain port. Then the drain port is closed, and multiple absorption components are placed in a coolant carrier tank filled with coolant and connected in series.

[0020] (2) Prepare an alkaline solution of 0.8 to 1.5 mol / L and discharge the alkaline solution into the outer shell of the absorption component through the liquid inlet. The volume of alkaline solution in each absorption component is equal. Then seal the liquid inlet.

[0021] (3) Close the small-diameter needle valve and disconnect the outlet end of the small-diameter needle valve pipeline from the gas inlet end of the multi-stage absorption device. Then open the large-diameter ball valve and slowly open the small-diameter needle valve to release the blast furnace gas discharged from the clean gas main pipeline for 10 to 30 seconds. Then close the small-diameter needle valve and reconnect the outlet end of the small-diameter needle valve pipeline to the gas inlet end of the multi-stage absorption device.

[0022] (4) Extract the current flow reading of the wet gas flow meter as Q1, and then slowly open the small diameter needle valve. The opening degree of the small diameter needle valve makes the gas flow rate 0.8 to 1.2 L / min. Maintain this state and use the multi-stage absorption device to absorb the blast furnace gas for 1.8 to 2.2 hours.

[0023] (5) Close the small-diameter needle valve and extract the current flow reading of the wet gas flow meter as Q2.

[0024] (6) Remove each absorption component and drain the absorbent liquid from each component into its corresponding temporary storage tank through the drain port. Simultaneously, clean the inside of the absorption component shell 1-2 times with deionized water. The cleaned liquid is also drained into the corresponding temporary storage tank. Measure the volume of absorbent liquid and pH value in each temporary storage tank; (record as W1, W2, ... pH respectively). A pH B ...;).

[0025] (7) Extract A ml of the absorption solution (e.g., 50 ml) from each temporary storage tank, then adjust the pH of the extracted absorption solution to 5.0–7.5 using acid and alkali solutions, then add A / 10 drops of potassium chromate indicator (e.g., 5 drops), each drop of potassium chromate indicator being 0.035–0.06 ml (i.e., the volume of 5 drops is 0.25 ml), and then titrate with silver nitrate solution. When the solution color changes from clear pale yellow to turbid yellow, the titration has reached the endpoint, and record the volume of silver nitrate solution consumed at this time as V.

[0026] (8) Obtain the weight of chloride ions in the absorption liquid using Formula I:

[0027]

[0028] Where: X is the mass of chloride ions in the absorbent in the temporary storage tank, in mg; W is the volume of the absorbent, in ml; V is the volume of silver nitrate standard titration solution consumed during titration, in mL; C is the concentration of silver nitrate standard titration solution, in mol / L; 36.5 is the molar mass of hydrogen chloride, in g / mol; A is the volume of absorbent extracted from the temporary storage tank in ml.

[0029] (9) Record the mass of chloride ions in the absorbent liquid in each temporary storage tank obtained in step (8) as X1, X2...X n Then, the concentration of hydrogen chloride in the blast furnace gas is obtained according to Formula II:

[0030]

[0031] Where: D: Concentration of hydrogen chloride in blast furnace gas, unit: mg / m³ 3 X1, X2...X n Q1: Mass of chloride ions in the absorbent liquid in each temporary storage tank, in mg; Q2: Flow rate reading at the beginning of the wet gas flow meter, in L; Q3: Flow rate reading at the end of the wet gas flow meter, in L.

[0032] Preferably, the alkaline solution in step (2) is a sodium hydroxide solution or a potassium hydroxide solution; the acid solution in step (7) is a nitric acid solution, and the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution.

[0033] Preferably, A ml is 0.060 to 0.065 times the volume of the alkaline solution added into the housing of the absorbent component.

[0034] Preferably, the plurality of absorption components specifically comprises two absorption components; the amount of alkaline solution added to each absorption component is 780–1200 ml.

[0035] Preferably, the gas flow rate in step (4) is: absorption time: number of absorption components: volume of alkaline solution added to each absorption component = (0.8~1.2L / min): (1.8~2.2 hours): 2: (780~820ml).

[0036] Preferably, the temporary storage tank is a volumetric flask, and the flexible hose is a polytetrafluoroethylene (PTFE) hose. The pipeline at the outlet of the flow meter is led into the atmosphere for venting. The connecting pipeline before the inlet of the primary absorption bottle should be as short as possible and insulated with heat tracing. The wet gas flow meter's range is 0–0.2 m. 3 / h.

[0037] The technical advantages of this invention are as follows:

[0038] (1) The present invention places the sampling port on the main clean gas pipeline after the bag filter and before the TRT (blast furnace gas residual pressure turbine power generation unit). The inlet is an existing large-diameter ball valve, which does not require modification to the existing test section. By preparing a sodium hydroxide solution of a certain concentration, and using the corresponding multi-stage absorption bottle, the opening of the needle valve is controlled to allow a certain amount of blast furnace gas to pass through within a certain time to complete the absorption reaction of hydrogen chloride and sodium hydroxide solution. The solution after absorption is measured using a chemical analysis method optimized for the specific blast furnace gas treated by the present invention, which determines the chloride ion concentration in the absorption liquid. Then, based on the total solution volume and gas volume, the hydrogen chloride content in the blast furnace gas is calculated optimally. Combining the composition of blast furnace gas and the physical properties of HCl, a complete hydrogen chloride absorption detection process has been formed through a large number of experiments, filling the gap in the industry for hydrogen chloride detection in blast furnace gas.

[0039] (2) The existing GB11896-89 standard specifies the appearance of a brick-red precipitate as the endpoint for titration. However, this invention targets blast furnace gas. During the research process, it was discovered that the absorbent produced by the blast furnace gas contains a large amount of carbonate and other unknown ions when titrating using the specific process described in this invention. If the standard method is used to determine the endpoint, a brick-red precipitate appears, and upon retesting with a ZD-2 automatic potentiometric titrator, the endpoint is found to be far exceeded. This invention sets the endpoint to a turbid yellow color. When the endpoint is retested with a ZD-2 automatic potentiometric titrator, the two results are completely consistent, indicating that the turbid yellow color setting used in this invention as the endpoint determination is correct and highly consistent with the specific measurement process of this invention. In other words, the titration endpoint set by this invention for its specific process makes the final measurement results more accurate and more applicable to the calculations of the various formulas set in this invention.

[0040] (3) The device of the present invention is simple to set up and does not require modification of the part to be tested. Through creative research, the proportional relationship between various parameters that can completely absorb chloride ions without causing equipment waste is discovered for the overall process of the present invention. Thus, the device of the present invention is reasonably set up and the process is fast, efficient and effective. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the connection of an apparatus for detecting hydrogen chloride in blast furnace gas according to one embodiment of the present invention.

[0042] Among them: 1-Main pipeline for clean coal gas, 2-Large diameter ball valve pipeline, 201-Large diameter ball valve, 3-Reducing diameter pipeline, 4-Small diameter needle valve pipeline, 401-Small diameter needle valve, 5-Insulation coating layer, 600-Shell shell of absorption component, 601-Liquid inlet, 602-Drain outlet, 603-Gas inlet hose, 604-Microporous aeration disc, 605-Exhaust outlet, 606-Absorbent liquid, 7-Coolant, 8-Coolant support tank, 9-Wet gas flow meter. Detailed Implementation

[0043] The technical solution of the present invention will be further described in conjunction with the embodiments:

[0044] A specific implementation method was carried out at a steel plant in Hebei Province. Using the existing DN15 sampling port of the main clean gas pipeline after the bag filter and before the TRT (Total Refrigerant Filter) as the main gas inlet, a large-diameter ball valve pipeline, a reducing pipeline, a small-diameter needle valve pipeline, a multi-stage absorption device, and a wet gas flow meter were sequentially installed. One end of the large-diameter ball valve pipeline was connected to the main clean gas pipeline, and the other end was connected to the reducing pipeline. A large-diameter ball valve was installed on the large-diameter ball valve pipeline. The inlet end of the small-diameter needle valve pipeline was connected to the reducing pipeline, and the outlet end was connected to the gas inlet end of the multi-stage absorption device. A small-diameter needle valve was installed on the small-diameter needle valve pipeline. The inlet diameter of the reducing pipeline matched the diameter of the large-diameter ball valve pipeline, and the outlet diameter of the reducing pipeline matched the diameter of the small-diameter needle valve pipeline. The inlet end of the wet gas flow meter was connected to the gas outlet of the multi-stage absorption device. The multi-stage absorption device includes a coolant carrying tank, coolant, and multiple absorption components. The coolant carrying tank is filled with coolant, and the multiple absorption components are connected in series within the coolant carrying tank. Each absorption component includes an absorption component shell, a liquid inlet, a drain outlet, an air inlet hose, a microporous aeration disc, and an exhaust outlet. The liquid inlet is located on the upper side wall of the absorption component shell, the drain outlet is located at the bottom of the absorption component shell, the bottom end of the air inlet hose extends into the inner bottom of the absorption component shell, and a microporous aeration disc is provided at the bottom end of the air inlet hose. An exhaust outlet is provided at the inner top of the absorption component shell, and the absorption component shell is filled with absorbent liquid. The inlet ends of the air inlet hoses of the multiple absorption components connected in series are connected to the exhaust outlet of the previous absorption component. The air inlet hose of the first absorption component is connected to the gas inlet end of the multi-stage absorption device, and the exhaust outlet of the last absorption component is connected to the gas outlet of the multi-stage absorption device.

[0045] In this implementation, all pipelines use PTFE flexible hoses. The large-diameter ball valve is DN15, and the reducing pipe converts the DN15 to DN8. The small-diameter needle valve is a DN8 needle valve. The multi-stage absorption device consists of two absorption bottles (i.e., two absorption components), one for the first stage and one for the second stage. The wet gas outlet pipeline is led into the atmosphere for venting. The insulation layer is an electric heating cable, powered by a 120W portable power supply. The connecting pipeline before the inlet of the first-stage absorption bottle is kept as short as possible and insulated. The aeration disc has 2mm pores, and the wet gas flow metering range is 0–0.2m. 3 / h, the concentration of sodium hydroxide solution added is 1.0mol / L.

[0046] The following embodiments all use the apparatus described in the specific implementation of the above-described embodiments.

[0047] Example 1

[0048] The specific testing steps are as follows:

[0049] 1. Prepare 10 L of 1.0 mol / L sodium hydroxide solution. Take 800 ml of the absorption solution and add it to volumetric flasks A and B respectively. First, open the liquid inlet of the primary absorption flask and the secondary absorption flask respectively, add deionized water to clean them, and then drain the solution through the drain port. Repeat this cleaning operation at least twice, and then tighten the drain port.

[0050] 2. Add the absorbent from volumetric flask A to the primary absorption flask, and add the absorbent from volumetric flask B to the secondary absorption flask. Tighten the liquid inlet.

[0051] 3. Set the DN8 needle valve to the closed position, disconnect the PTFE hose at the outlet end of the small-diameter needle valve pipeline (DN8 needle valve), open the DN15 ball valve, slowly adjust the opening of the needle valve, and release the gas through the outlet end of the small-diameter needle valve pipeline for 10-30 seconds. Then close the DN8 needle valve and reconnect the PTFE hose at the outlet end of the small-diameter needle valve pipeline.

[0052] 4. Record the reading Q1 of the wet gas flow meter at this time. At the same time, slowly open the DN8 needle valve, observe the reading of the wet gas flow meter, adjust the opening of the needle valve, and control the gas flow rate at 0.8~1.2L / min for 2 hours of absorption.

[0053] This embodiment meets the following requirements: gas flow rate (0.8~1.2L / min): absorption time (2h): number of absorption components (2): volume of alkaline solution added to each absorption component (800ml) = (0.8~1.2L / min): (1.8~2.2 hours): 2: (780~820ml).

[0054] 5. After 2 hours, close the DN8 needle valve and record the wet gas flow meter reading Q2.

[0055] 6. Disconnect the PTFE hose at the outlet of the small-diameter needle valve. Open the drain port of the first-stage absorption bottle and pour the absorbent from the first-stage absorption bottle into volumetric flask A. Then, rinse the absorption bottle 1-2 times with a small amount of deionized water, pouring the rinsing solution into volumetric flask A as well. Repeat the same operation for the second-stage absorption bottle, pouring the absorbent obtained from the second-stage absorption bottle and the rinsing solution into volumetric flask B. Use a graduated cylinder to measure the volume of absorbent in volumetric flask A and volumetric flask B, and record the values ​​W1, W2, and pH, respectively. A pH B .

[0056] 7. Take 50 ml of absorption solution (A is 50), add 1 drop of phenolphthalein indicator according to the pH value of the absorption solution, then slowly add nitric acid while shaking until no bubbles appear in the absorption solution. Use a pH meter to measure the pH value to be about 5.5. Add sodium hydroxide to adjust the pH to 7.2, add 5 drops of potassium chromate indicator, and titrate with 0.0029 mol / L silver nitrate solution. When the solution color changes from clear light yellow to turbid yellow, it indicates that the titration has reached the endpoint. Record the titration volume V.

[0057] 8. Use formula I' to calculate the mass of chloride ions in the two-stage absorption solutions, and record them as X1 and X2 respectively;

[0058]

[0059] 9. Calculate the concentration of hydrogen chloride in blast furnace gas using formula II':

[0060]

[0061] X1 and X2 are the masses of chloride ions in the absorbent liquid of volumetric flasks A and B, respectively, in mg. The concentration of hydrogen chloride D in the blast furnace gas is obtained.

[0062] The results were recorded and calculated as shown in Table 1. Table 1 contains the data for Example 1.

[0063] Table 1

[0064]

[0065] Comparative Example 1

[0066] This comparative example adds the primary and secondary absorption bottles of Example 1 to a tertiary series absorption bottle (i.e., it does not meet the requirement of the proportional relationship between the flow rate and the absorbent in step (4)). Other settings are the same as in Example 1. After the same steps as in Example 1 and the same parameter settings and calculations, the results shown in Table 2 are obtained. Table 2 shows the data of Comparative Example 1.

[0067] Table 2

[0068]

[0069] Table 2 shows that, compared to Example 1, the chloride ion concentration in the third-stage absorbent is <1 mg / L, and the pH in the third stage is 13.7, indicating that the third-stage absorbent is basically not consumed. This means that, under the same conditions, the second-stage absorption can fully absorb hydrogen chloride. The third stage does not meet the requirement of a proportional relationship between the flow rate and the absorbent in step (4), thus failing to achieve its technical effect and resulting in wasted costs. This demonstrates that under the specific measurement conditions set by this invention, for a specific amount of gas, it is necessary to set the absorbent and the number of absorption stages specified in this invention; otherwise, the detection objective cannot be achieved.

[0070] Comparative Example 2

[0071] This comparative example increases the amount of coal gas processed from 130L to 260L by adjusting the gas flow rate, that is, doubling the flow rate in step (4) (i.e., doubling it) (i.e., not satisfying the corresponding proportional relationships). The remaining settings are the same as in Example 1. The results are as follows:

[0072]

[0073] Compared to Example 1, the pH of the primary absorbent in this comparative example decreased to 8.3, the pH of the secondary absorbent decreased to 9.5, and the chloride ion concentration in the secondary absorbent reached as high as 7.5 mg / L. This indicates that the absorbent was penetrated and the chloride ions were not completely absorbed. This demonstrates that under the specific measurement conditions set by this invention, for a specific amount of coal gas, it is necessary to set a matching absorbent and a matching number of absorption stages.

[0074] Comparative Example 3

[0075] This comparative example doubles both the gas absorption time and the amount of gas processed by adjusting the gas flow rate and absorption time (i.e., it does not satisfy the corresponding proportional relationships), while the rest of the settings are the same as in Example 1. The results are as follows:

[0076]

[0077] Compared to Example 1, the pH of the primary absorbent decreased to 8.4, the pH of the secondary absorbent decreased to 9.7, and the chloride ion concentration in the secondary absorbent reached as high as 8.9 mg / L. This indicates that the absorbent was permeated and the chloride ions were not completely absorbed.

[0078] Comparative Example 4

[0079] In the titration process of this comparative example in step (7), the formation of a brick-red precipitate as specified in the existing standard was used as the titration endpoint. Other settings were the same as in Example 1. The same steps were followed for measurement as in Example 1. When the measurement was repeated using a ZD-2 type automatic potentiometric titrator, it was found that the titration endpoint had been far exceeded. That is, the existing titration standard is not applicable to the blast furnace gas targeted by this invention.

[0080] Comparative Example 5

[0081] This comparative example did not use a coolant or an insulation layer; all other settings were the same as in Example 1. Measurements were performed using the same steps as in Example 1. However, when retested using a ZD2 automatic potentiometric titrator, the titration endpoint was not reached. The insulation and heat tracing prevent condensation of the gas before it enters the absorption liquid during sampling. HCl dissolves in the condensate (at room temperature and pressure, 1L of water can absorb at least 500L of hydrogen chloride gas), leading to lower test results. The coolant, applied after this stage, lowers the absorption liquid temperature to 10-20℃. This low temperature promotes hydrogen chloride absorption and prevents insufficient absorption, which would result in lower results. Without a coolant or insulation layer, the technical effects of this invention cannot be achieved. This demonstrates that the settings at each stage of this invention are coordinated and mutually supportive, rather than acting independently; each setting has a strong synergistic effect.

[0082] The embodiments and comparative examples described above are merely illustrative and do not limit the scope of protection of the technical solutions. The omission of comparative technical features does not imply the lack of prominent substantive features; rather, they are merely descriptive of the arrangement.

Claims

1. A device for detecting hydrogen chloride in blast furnace gas, characterized in that, This includes large-diameter ball valve pipelines, reducing pipelines, small-diameter needle valve pipelines, multi-stage absorption devices, and wet gas flow meters; One end of the large-diameter ball valve pipeline is connected to the main clean gas pipeline, and the other end is connected to the reducing pipeline. A large-diameter ball valve is installed on the large-diameter ball valve pipeline. The inlet end of the small-diameter needle valve pipeline is connected to the reducing pipeline, and the outlet end is connected to the gas inlet end of the multi-stage absorption device. A small-diameter needle valve is installed on the small-diameter needle valve pipeline. The inlet diameter of the reducing pipeline matches the diameter of the large-diameter ball valve pipeline, and the outlet diameter of the reducing pipeline matches the diameter of the small-diameter needle valve pipeline. The inlet of the wet gas flow meter is connected to the gas outlet of the multi-stage absorption device. The multi-stage absorption device includes a coolant carrying tank, coolant, and multiple absorption components; The coolant carrier tank is filled with coolant, and multiple absorption components are connected in series within the coolant carrier tank. Each absorption component includes an absorption component shell, a liquid inlet, a drain outlet, an air inlet hose, a microporous aeration disc, and an exhaust outlet. The liquid inlet is located on the upper side wall of the absorption component shell, the drain outlet is located at the bottom end of the absorption component shell, the bottom end of the air inlet hose extends into the inner bottom of the absorption component shell, and a microporous aeration disc is provided at the bottom end of the air inlet hose. An exhaust outlet is provided at the inner top of the absorption component shell, and the absorption component shell is filled with absorbent liquid. The inlet ends of the air inlet hoses of the multiple absorption components connected in series are connected to the exhaust outlet of the previous absorption component. The air inlet hose of the first absorption component is connected to the gas inlet end of the multi-stage absorption device, and the exhaust outlet of the last absorption component is connected to the gas outlet of the multi-stage absorption device.

2. The apparatus for detecting hydrogen chloride in blast furnace gas according to claim 1, characterized in that, The connection point between the large-diameter ball valve pipeline and the main clean gas pipeline is located after the bag filter of the main clean gas pipeline and before the TRT device.

3. The apparatus for detecting hydrogen chloride in blast furnace gas according to claim 1, characterized in that, The large-diameter ball valve is a DN15 ball valve; the small-diameter needle valve is a DN8 needle valve.

4. The apparatus for detecting hydrogen chloride in blast furnace gas according to claim 1, characterized in that, The pore size of the microporous aeration disc is 1.8–2.5 mm.

5. The apparatus for detecting hydrogen chloride in blast furnace gas according to claim 1, characterized in that, Thermal insulation coatings are installed on large-diameter ball valve pipes, reducing pipes, and small-diameter needle valve pipes.

6. A method for detecting hydrogen chloride in blast furnace gas, characterized in that, The method is performed using the apparatus for detecting hydrogen chloride in blast furnace gas as described in any one of claims 1-5, and includes the following steps: (1) Deionized water is discharged through the liquid inlet of the absorption component to clean the outer shell of the absorption component. The cleaned water is discharged through the drain port. Then the drain port is closed. Multiple absorption components are placed in a coolant carrying tank filled with coolant and connected in series. (2) Prepare an alkaline solution of 0.8 to 1.5 mol / L and discharge the alkaline solution into the outer shell of the absorption component through the liquid inlet. The volume of alkaline solution in each absorption component is equal. Then seal the liquid inlet. (3) Close the small-diameter needle valve and disconnect the outlet end of the small-diameter needle valve pipeline from the gas inlet end of the multi-stage absorption device. Then open the large-diameter ball valve and slowly open the small-diameter needle valve to release the blast furnace gas discharged from the clean gas main pipeline for 10 to 30 seconds. Then close the small-diameter needle valve and reconnect the outlet end of the small-diameter needle valve pipeline to the gas inlet end of the multi-stage absorption device. (4) Extract the current flow reading of the wet gas flow meter as Q1, and then slowly open the small-diameter needle valve. The opening of the small-diameter needle valve makes the gas flow rate 0.8 to 1.2 L / min. The gas is discharged into the alkaline solution through the microporous aeration disc. After the gas and alkaline solution react through multiple absorption components connected in series, the gas is discharged into the wet gas flow meter through the gas outlet of the multi-stage absorption device. Maintain this state and use the multi-stage absorption device to absorb the blast furnace gas for 1.8 to 2.2 hours. (5) Close the small-diameter needle valve and extract the current flow reading of the wet gas flow meter as Q2; (6) Take out each absorption component and drain the absorbent liquid in each absorption component into the corresponding temporary storage tank through the drain port. At the same time, use deionized water to clean the inside of the absorption component shell 1 to 2 times. After cleaning, the liquid is also drained into the corresponding temporary storage tank. The volume of absorbent liquid and pH value in the different temporary storage tanks are measured respectively. (7) Extract A ml of absorption liquid from each temporary storage tank, then adjust the pH of the extracted absorption liquid to 5.0-7.5 using acid and alkali solutions, then add A / 10 drops of potassium chromate indicator, each drop of potassium chromate indicator being 0.035-0.06 ml, and then titrate with silver nitrate solution. When the solution color changes from clear light yellow to turbid yellow, the titration reaches the endpoint, and record the volume of silver nitrate solution consumed at this time as V; (8) Obtain the weight of chloride ions in the absorption liquid using Formula I: Where: X is the mass of chloride ions in the absorbent in the temporary storage tank, in mg; W is the volume of the absorbent, in ml; V is the volume of silver nitrate standard titration solution consumed during titration, in mL; C is the concentration of silver nitrate standard titration solution, in mol / L; 36.5 is the molar mass of hydrogen chloride, in g / mol; A is the volume of absorbent extracted from the temporary storage tank in ml. (9) Record the mass of chloride ions in the absorbent liquid in each temporary storage tank obtained in step (8) as X1, X2...X n Then, the concentration of hydrogen chloride in the blast furnace gas is obtained according to Formula II: Where: D: Concentration of hydrogen chloride in blast furnace gas, unit: mg / m³ 3 X1, X2...X n Q1: The mass of chloride ions in the absorbent liquid in each of the n temporary storage tanks, in mg; Q2: The flow rate reading at the beginning of the wet gas flow meter, in L; Q3: The flow rate reading at the end of the wet gas flow meter, in L.

7. The method for detecting hydrogen chloride in blast furnace gas according to claim 6, characterized in that, The alkaline solution in step (2) is a sodium hydroxide solution or a potassium hydroxide solution; the acid solution in step (7) is a nitric acid solution, and the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution.

8. The method for detecting hydrogen chloride in blast furnace gas according to claim 6, characterized in that, A ml is 0.060 to 0.065 times the volume of the alkaline solution added into the outer shell of the absorbent component.

9. The method for detecting hydrogen chloride in blast furnace gas according to claim 6, characterized in that, The plurality of absorption components specifically comprises two absorption components; the amount of alkaline solution added to each absorption component is 780–1200 ml.

10. The method for detecting hydrogen chloride in blast furnace gas according to claim 6, characterized in that, The gas flow rate in step (4) is: absorption time: number of absorption components: volume of alkaline solution added to each absorption component = (0.8~1.2L / min): (1.8~2.2 hours): 2: (780~820ml).

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