A method for desulfurization by utilizing low-temperature flue gas waste heat of blast furnace hot blast stove

Abstract

The application provides a method for synergistic desulfurization of low-temperature flue gas waste heat of a blast furnace hot blast stove, and the method uses the low-temperature flue gas waste heat of the hot blast stove to dry coke, realizes flue gas desulfurization while drying the coke, and integrates the drying of the coke and the flue gas desulfurization; meanwhile, the coke is modified by using an inhibitor to inhibit the adsorption of sulfur dioxide in the flue gas by the coke in the drying process, and the original inhibitory effect is removed by using a desorption agent, so that the adsorption capacity of the coke powder obtained after drying to sulfur dioxide in the tail gas is strengthened, and the adsorption effect of the coke powder to sulfur dioxide is obviously improved. The application not only solves the problems of low flue gas waste heat utilization rate and high flue gas desulfurization cost, but also improves the treatment efficiency and reduces the construction cost by using the method.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical energy conservation and environmental protection, especially the field of blast furnace hot blast stove flue gas utilization, specifically involving a method for synergistic desulfurization using low-temperature flue gas waste heat from blast furnace hot blast stove. Background Technology

[0002] Blast furnace hot blast stoves are blast furnace ironmaking equipment that uses forced-air heating. Typically, one blast furnace is equipped with 3-4 hot blast stoves. Their function is to continuously provide the blast furnace with high-temperature hot air exceeding 1000℃. Blast furnace ironmaking accounts for 48% of the total energy consumption of the steel industry, with hot blast stoves consuming one-quarter of that energy. The flue gas from blast furnace hot blast stoves is an important waste heat resource in the ironmaking process, and its recovery and utilization play a crucial role in energy conservation and emission reduction.

[0003] Common methods for utilizing waste heat from hot blast stoves include installing heat exchangers, waste heat boilers, refrigeration equipment to generate cooling capacity using heat energy, and methods for drying coke, preheating coal gas, and producing combustion air. For example, a stove with a flue gas emission of 20,000 Nm³... 3 For a blast furnace with a capacity of [number] h, if a heat exchanger is installed in the hot blast stove to reduce its exhaust gas temperature from 350℃ to 148℃, 1349 kW of heat can be obtained, equivalent to 1432 tons of standard coal annually. Shi Guohua et al. utilized low-temperature flue gas from hot blast stoves below 260℃. Taking a steel plant with an annual output of 4 million tons as an example, the waste heat recovery reached 798 MW, with a static recovery period of approximately 4 years for heating, demonstrating significant economic benefits. After the waste heat was fully utilized, the flue gas temperature from the hot blast stove was below 60℃. Dong Hui et al. proposed that the flue gas from the hot blast stove first be cooled by a flue gas-type refrigeration unit, and then the cooled flue gas be used to preheat combustion air and coal gas, ultimately reducing the exhaust gas temperature to around 100℃. Shandong Iron and Steel Group (Shandong Steel) has adopted a hot blast stove flue gas preheating and coke drying technology. After coke drying, the temperature of the hot blast stove flue gas drops from 180℃ to 40℃, while the temperature of the coke entering the furnace rises by about 30℃. The moisture content of the purchased coke decreases by 3%-7%, generating economic benefits of approximately 500,000 yuan. The reduced coke moisture content leads to an increase in the blast furnace top temperature. The increased top temperature also reduces scaling on the blast furnace gas residual pressure turbine power generation unit, resulting in an annual increase in power generation and economic benefits of approximately 2.7 million yuan.

[0004] In conclusion, improving the thermal efficiency of hot blast stoves and recycling their flue gas are crucial for industrial energy conservation and emission reduction. If this waste heat can be recovered and utilized, it will have a positive impact on alleviating global energy pressures.

[0005] Furthermore, reducing pollutants from the steel industry has become a top priority for environmental protection efforts, both within the steel sector and globally. The ultra-low emission limit for SO2 from blast furnace hot blast stoves is no higher than 50 mg / m³. 3Currently, the SO2 concentration in the flue gas of hot blast stoves is generally higher than the ultra-low emission limit, and desulfurization of hot blast stoves has become an important problem faced by most steel plants.

[0006] Currently, the main flue gas desulfurization technologies for hot blast stoves include activated carbon desulfurization, sodium bicarbonate dry desulfurization (SDS), and calcium-based fixed-bed desulfurization. Taiyuan Iron & Steel (TISCO) uses activated carbon desulfurization technology, and the environmental protection effect after operation is very significant, reducing annual SO2 emissions from 6821 tons to 341 tons, with a desulfurization efficiency of 95%. Changzhi Iron & Steel (Changzhi) utilizes the SDS process, reducing the average inlet SO2 concentration to 83.84 mg / m³. 3 The SO2 concentration at the outlet is less than 30 mg / m³. 3 It achieved ultra-low emission standards, with a removal rate of up to 85.91%. Meigang utilizes calcium-based fixed-bed flue gas desulfurization technology, achieving a removal rate of up to 85.91% when the flue gas concentration is reduced from 150 mg / Nm³. 3 Reduced to 50 mg / Nm 3 The following method uses highly active Ca(OH)2 desulfurizing agent to adsorb acidic gases such as SO2 in flue gas, achieving a desulfurization design efficiency of over 76.7%.

[0007] While existing desulfurization technologies offer good results, their investment and operating costs are relatively high. Therefore, developing a hot blast stove flue gas desulfurization technology that is highly adaptable, easy to operate, and has low investment and operating costs has become an important trend in the development of desulfurization technology. Summary of the Invention

[0008] The purpose of this invention is to provide a method for synergistic desulfurization using the waste heat of low-temperature flue gas from a blast furnace hot blast stove. This method utilizes the waste heat of the low-temperature flue gas from the hot blast stove to dry coke, achieving flue gas desulfurization simultaneously with coke drying. The drying of coke and the desulfurization of flue gas are integrated into one process. Sulfur dioxide in the flue gas reacts with the water vapor generated during drying to form sulfuric acid in the non-coke area of ​​the integrated system, achieving primary desulfurization through chemical reaction. This invention also employs inhibitors to modify the coke, inhibiting its adsorption of sulfur dioxide from the flue gas during the drying process. Then, a de-inhibiting agent is used to remove the original desulfurization inhibition effect of the coke powder produced during the coke drying process and enhance the adsorption capacity of the dried coke powder for sulfur dioxide in the tail gas, significantly improving its adsorption effect and achieving secondary desulfurization through physical adsorption. This invention not only solves the problems of low utilization rate of flue gas waste heat and high cost of flue gas desulfurization, but also improves processing efficiency and reduces construction costs.

[0009] The specific technical solution of this invention is as follows:

[0010] A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove includes the following steps:

[0011] 1) Low-temperature flue gas from the blast furnace hot blast stove dries coke and performs primary desulfurization;

[0012] 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder and then desulfurized twice.

[0013] In step 1), the waste heat of the low-temperature flue gas from the blast furnace hot blast stove is used to dry the coke. The water vapor generated during coke drying, SO2 in the flue gas, and oxygen react to produce sulfuric acid, thereby reducing the SO2 concentration in the flue gas and achieving primary desulfurization.

[0014] Preferably, in step 1), the coke is coke treated with an inhibitor;

[0015] Alternatively, in step 1), the inhibitor is atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove to dry the coke. Considering cost and ease of processing, this invention atomizes the inhibitor and mixes it into the low-temperature flue gas of the blast furnace hot blast stove. While the low-temperature flue gas of the blast furnace hot blast stove is being dried by the coke, the inhibitor can also treat the coke at the same time, inhibiting its adsorption of sulfur dioxide.

[0016] In step 1), the low-temperature flue gas from the blast furnace hot blast stove is low-grade low-temperature flue gas from the blast furnace hot blast stove after passing through a heat exchanger; the temperature of the low-temperature flue gas from the blast furnace hot blast stove is 130-190℃; the sulfur dioxide concentration in the low-temperature flue gas from the blast furnace hot blast stove is 50-1000ppm, preferably 50-400ppm; and the flow rate of the low-temperature flue gas from the blast furnace hot blast stove is 100,000-350,000 m³ / h. 3 / h; preferably 150000m 3 / h.

[0017] In step 1), the amount of inhibitor used is 0.2%-1.0% of the coke mass;

[0018] In step 1), the inhibitor comprises the following raw materials in parts by weight: 30-40 parts sodium ditridecyl sulfosuccinate, 20-25 parts dewaxed kerosene, 10-15 parts 4-methyl-2-pentanol (MIBC), 15-20 parts acetone, 10-15 parts diethyl phthalate (DEP), 5-10 parts dodecane, 5-10 parts methyl dodecanoate, and 5-10 parts octanoic acid;

[0019] The inhibitor is prepared by mixing the above-mentioned raw materials evenly.

[0020] In step 1), the coke is blast furnace coke with a moisture content of 2-12% and a particle size of 10.0mm-70mm.

[0021] In step 1), the drying time is 2-8 hours;

[0022] In step 1), the amount of coke dried is 100-150 t / h;

[0023] In step 1), after drying the coke, the liquid produced during the drying process is collected; this proves that sulfur dioxide reacts with water and oxygen to form sulfate ions, and that sulfur dioxide is partially removed.

[0024] In step 2), the coke powder is produced by drying coke with low-temperature flue gas from a blast furnace hot blast stove, and the coke powder yield is 5-10% of the coke mass.

[0025] Preferably, in step 2), the coke powder is treated with an inhibitor.

[0026] Alternatively, in step 2), the desulfurizing agent is atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove after treatment in step 1), and then treated with coke powder. Considering cost and ease of processing, atomizing the desulfurizing agent and mixing it into the low-temperature flue gas of the blast furnace hot blast stove after treatment in step 1) removes the original desulfurization inhibition effect of coke powder generated during the coke drying process. It can also promote the absorption of sulfur dioxide by coke powder, enhance the adsorption capacity of the dried coke powder for sulfur dioxide in the tail gas, and significantly improve its adsorption effect on sulfur dioxide, thus achieving the purpose of secondary desulfurization through physical adsorption.

[0027] In step 2), the temperature of the low-temperature flue gas from the blast furnace hot blast stove after the treatment in step 1) is 60℃-90℃;

[0028] In step 2), the amount of the depressant is 0.3%-1.5% of the mass of the coke powder;

[0029] In step 2), the flow rate of the low-temperature flue gas from the blast furnace hot blast stove after the treatment in step 1) is 100,000-350,000 m³ / h. 3 / h; Coke powder processing time: 30s-90s;

[0030] In step 2), the depressant comprises the following raw materials in parts by weight: 20-30 parts sodium octadecyl sulfonate, 20-25 parts sodium dodecylbenzene sulfonate, 15-20 parts polyoxyethylene ether fatty alcohol, 10-15 parts sodium fatty alcohol polyoxyethylene ether sulfate, 10-20 parts sodium pyrophosphate, 5-10 parts triethanolamine, 5-10 parts diethylene glycol butyl ether, and 2-10 parts sodium hypotriacetate.

[0031] The method for preparing the depressant is as follows: after mixing the raw materials in the above formula evenly, the product is obtained.

[0032] This invention addresses the challenges of low waste heat utilization and high flue gas desulfurization costs by providing a novel method for synergistic desulfurization using low-temperature waste heat from flue gas. It utilizes the low-temperature waste heat from a hot blast stove to dry coke, achieving flue gas desulfurization simultaneously with coke drying. This integrated approach to coke drying and flue gas desulfurization improves overall efficiency and reduces construction costs. Furthermore, to inhibit the adsorption of sulfur dioxide from the flue gas by coke during drying, the invention modifies the coke using an inhibitor. To enhance the adsorption capacity of coke powder for sulfur dioxide in the tail gas (low-temperature flue gas from the blast furnace hot blast stove after primary desulfurization), an inhibitor is used to remove the original inhibitory effect, significantly improving the adsorption efficiency. This invention reveals the mechanism of simultaneous desulfurization during coke drying and the synergistic treatment method of coke powder adsorption and desulfurization. The relevant treatment methods, raw materials, and process parameters have been determined, resulting in a new technology that has been successfully applied industrially with significant results.

[0033] The inhibitor designed in this invention utilizes the presence of dewaxed kerosene to create an oil-water isolation environment, preventing sulfur dioxide from contacting the coke. Sodium ditridecyl sulfosuccinate, a highly oil-soluble hydrophobic surfactant with excellent performance, further and more quickly stabilizes the isolation environment. The presence of 4-methyl-2-pentanol and n-octanoic acid makes the oil-water interfacial tension more balanced and durable. The interaction of diethyl phthalate and acetone increases the hydrophobicity of the coke surface, enhancing the effectiveness of the oil-water isolation environment in blocking sulfur dioxide. Different reagents play different roles at the mesoscopic and microscopic scales. At the mesoscopic scale, dodecane acts on the polar sites on the coke surface and seals water molecules within the pores, promoting continuous oil film formation and maximizing coverage of all coke surfaces. At the microscopic scale, methyl dodecanoate interacts with both hydrophilic and hydrophobic sites on the coke surface. Simultaneously, their molecular chains interact through van der Waals and hydrophobic forces, and the functional groups of each molecule work synergistically to form strong intermolecular forces. Ultimately, this results in a good and stable liquid barrier layer on the coke surface, significantly reducing the adsorption of sulfur dioxide by the coke. Through the additive and synergistic effects of the various inhibitory components, the coke essentially does not adsorb sulfur dioxide.

[0034] To enhance the adsorption capacity of coke powder for sulfur dioxide in exhaust gas, an inhibitor is used to remove the original inhibitory effect. This inhibitor disrupts the oil-water barrier balance, destroys polar sites on the surface, and removes the liquid barrier layer on the coke surface. Different reagents have varying effects on destroying different inhibitors; after multiple rounds of trials, the aforementioned ratio was determined. Furthermore, the inhibitor not only destroys the original inhibitor's effect but also promotes the absorption of sulfur dioxide by the coke powder. For example, triethanolamine not only destroys inhibitors but also better promotes the absorption of acidic gases such as sulfur dioxide at lower temperatures. Therefore, coke powder that has absorbed sulfur dioxide from the flue gas and cooled down will not pollute the environment when stockpiled; instead, it will become more stable. The coke powder that has adsorbed sulfur dioxide can be used for sintering; it can also be washed with water to obtain a dilute sulfuric acid solution, which can then be dried and utilized; additionally, the coke powder can be heated to enrich sulfur dioxide for the production of sulfuric acid or sulfur.

[0035] Compared with existing technologies, this invention addresses the challenges of low waste heat utilization and high desulfurization costs associated with blast furnace hot blast stove flue gas. It provides a new technology for synergistic desulfurization using low-temperature waste heat utilization of flue gas. This technology utilizes low-temperature flue gas from the hot blast stove to dry coke, achieving flue gas desulfurization simultaneously with coke drying. Research shows that flue gas flow rate, flue gas temperature, and drying time all affect the coke drying rate, with flow rate and drying time having a greater impact, while flue gas temperature has a smaller impact. The desulfurization rate is related to the moisture content of the coke and the sulfur dioxide concentration in the flue gas; the higher the moisture content of the coke and the lower the sulfur dioxide concentration in the flue gas, the higher the desulfurization rate. The reason why the coke drying process can desulfurize is that the water vapor, SO2, and oxygen generated during coke drying react to form sulfuric acid, thereby reducing the SO2 concentration in the flue gas (primary desulfurization). The coke powder produced during the coke drying process, due to its large specific surface area, can adsorb SO2, further desulfurizing it (secondary desulfurization). With an initial SO2 concentration of 80.72 ppm and a coke moisture content of 8.29%, the SO2 emission reduction rate under steam chemical reaction was 49.88%, and the SO2 emission reduction rate under physical adsorption by coke powder was 81.46%, resulting in a total SO2 emission reduction rate of 90.71%. During the coke drying process, the coke was modified with an inhibitor, preventing SO2 adsorption and ensuring that SO2 gas did not remain in the coke. The coke powder obtained after drying was treated with a de-inhibiting agent to promote its adsorption of sulfur dioxide, thereby enhancing the adsorption capacity and improving the secondary desulfurization effect.

[0036] After industrial application, the method provided by this invention demonstrates good waste heat utilization and desulfurization effects. The flue gas temperature decreased from 165℃ to 92℃, and the SO2 concentration decreased from 80.72 ppm to 7.5 ppm, which meets the ultra-low emission standards (<50 mg / m³) for China's steel industry. 3 It has achieved ultra-low emission standards, with a total emission reduction rate of 90.71%. Attached Figure Description

[0037] Figure 1 SEM images of coke powder, dry coke, and wet coke: (a) coke powder 2000x, (b) coke powder 16000x, (c) dry coke 100x, (d) dry coke 500x, (e) wet coke 100x, (f) wet coke 500x. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0040] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0041] The raw material coke used in this invention comes from a steel plant in China. The elemental and industrial analyses of the coke are shown in Table 1. The coke particle size is 10.0 mm to 70 mm.

[0042] Table 1. Elemental and industrial analysis of coke (wt%)

[0043] coke 0.9 83.45 0.21 0.68 1.84 8.29 11.88 1.25 78.58

[0044] Note: In Table 1, M ad – Moisture; A ad – Ash content; V ad -Volatile components; FC ad - Fixed carbon; The elements contained in coke, besides N, C, H, S, and O, are not shown. The remaining amount is ash and unavoidable impurities.

[0045] The following are the methods for calculating the drying rate of coke and the SO2 emission reduction rate:

[0046] To visually represent the effect of coke drying, the coke drying rate is used as the evaluation standard, and its calculation formula is as follows:

[0047]

[0048] Where α is the drying rate of coke, m1 is the mass (g) of the coke sample before drying, m2 is the mass (g) of the coke sample after drying, and m0 is the mass (g) of water contained in the coke sample.

[0049] To visually represent the SO2 removal effect, the SO2 emission reduction rate is used as the evaluation criterion, and its calculation formula is as follows:

[0050]

[0051] Where β is the SO2 emission reduction rate, C1 is the SO2 concentration (ppm) in the untreated raw flue gas, and C2 is the SO2 concentration (ppm) in the treated flue gas.

[0052] The following are specific examples and experimental results:

[0053] Example 1

[0054] A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove includes the following steps:

[0055] 1) Low-temperature flue gas drying of coke in blast furnace hot blast stove, with primary desulfurization:

[0056] 1-1) Preparation of inhibitor: According to the mass parts, 31 parts of sodium ditridecyl sulfosuccinate, 20 parts of dewaxed kerosene, 10 parts of 4-methyl-2-pentanol (MIBC), 16 parts of acetone, 10.5 parts of diethyl phthalate (DEP), 5.5 parts of dodecane, 6 parts of methyl dodecanoate and 5 parts of n-octanoic acid are mixed and stirred evenly to obtain the inhibitor;

[0057] 1-2) The prepared inhibitor was atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove. The temperature of the low-temperature flue gas was 175℃, the sulfur dioxide concentration was 75.84ppm, and the flue gas flow rate was 150,000 m³ / h. 3 The coke drying capacity is 130 t / h. Coke (coke parameters are shown in Table 1) is treated with low-temperature flue gas from the blast furnace hot blast stove mixed with atomization inhibitor. The coke moisture content is 8.29%, the inhibitor dosage is 0.56% of the coke mass, and the coke drying time is 2 hours. After drying, the liquid and coke powder produced are collected. The temperature of the treated low-temperature flue gas from the blast furnace hot blast stove is 80℃, which is used as tail gas for subsequent secondary desulfurization treatment. The sulfur dioxide concentration in the tail gas is detected to be 50.84 ppm. After primary desulfurization, the SO2 emission reduction rate is 32.96%.

[0058] 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder for secondary desulfurization:

[0059] 2-1) Preparation of the depressant: According to the mass parts, 21 parts of sodium octadecyl sulfonate, 22 parts of sodium dodecylbenzene sulfonate, 15 parts of polyoxyethylene ether fatty alcohol, 11 parts of fatty alcohol polyoxyethylene ether sodium sulfate, 11 parts of sodium pyrophosphate, 6 parts of triethanolamine, 6 parts of diethylene glycol butyl ether, and 3 parts of sodium hypotriacetate are mixed and stirred evenly to obtain the depressant;

[0060] 2-2) The prepared inhibitor is atomized and mixed into the low-temperature flue gas (tail gas) of the blast furnace hot blast stove after the treatment in step 1) to jointly treat the coke powder produced after drying coke. The amount of inhibitor is 0.68% of the mass ratio of coke powder, and the tail gas flow rate is 150,000 m³ / h. 3 / h, the coke powder output is 7.5% of the coke mass (the proportion of coke mass), the processing time is 60s; after the secondary desulfurization, the sulfur dioxide concentration in the flue gas is 14.36ppm, the flue gas temperature is 60℃, the total SO2 emission reduction rate reaches 81.07%, and the coke drying rate is 74%.

[0061] Example 2

[0062] A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove includes the following steps:

[0063] 1) Low-temperature flue gas drying of coke in blast furnace hot blast stove, with primary desulfurization:

[0064] 1-1) Preparation of inhibitor: According to the mass parts, 35 parts of sodium ditridecyl sulfosuccinate, 23 parts of dewaxed kerosene, 12 parts of 4-methyl-2-pentanol, 18 parts of acetone, 12 parts of diethyl phthalate (DEP), 7 parts of dodecane, 8 parts of methyl dodecanoate and 8 parts of n-octanoic acid are mixed and stirred evenly to obtain the inhibitor.

[0065] 1-2) The prepared inhibitor was atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove. The temperature of the low-temperature flue gas was 180℃, the sulfur dioxide concentration was 50.54ppm, and the flue gas flow rate was 150,000 m³ / h. 3 / h, the low-temperature flue gas from the blast furnace hot blast stove mixed with atomization inhibitor was used to treat coke (coke indicators are shown in Table 1). The coke moisture content was 8.29%, the amount of inhibitor was 0.25% of the coke mass, the drying time was 2h, and the drying rate was 130t / h. After drying the coke, the liquid produced during the drying process was collected, and the coke powder produced was also collected. The temperature of the treated low-temperature flue gas from the blast furnace hot blast stove was 84℃, which was used as tail gas for subsequent secondary desulfurization treatment. The sulfur dioxide concentration in the tail gas was detected to be 30.20ppm. After one desulfurization, the SO2 emission reduction rate was 40.25%.

[0066] 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder for secondary desulfurization:

[0067] 2-1) Preparation of the depressant: According to the following mass parts, 23 parts of sodium octadecyl sulfonate, 22 parts of sodium dodecylbenzene sulfonate, 18 parts of polyoxyethylene ether fatty alcohol, 12 parts of fatty alcohol polyoxyethylene ether sodium sulfate, 16 parts of sodium pyrophosphate, 7 parts of triethanolamine, 7.8 parts of diethylene glycol butyl ether, and 6.7 parts of sodium hypotriacetate are mixed and stirred evenly to obtain the depressant;

[0068] 2-2) The prepared desulfurizing agent was atomized and mixed into the low-temperature flue gas (tail gas) of the blast furnace hot blast stove after step 1) to jointly treat the coke powder produced after drying coke. The amount of desulfurizing agent was 0.32% of the mass ratio of coke powder, the coke powder yield was 5% of the coke mass, and the treatment time was 60s. After the secondary desulfurization, the sulfur dioxide concentration in the flue gas was 13.87ppm, the flue gas temperature was 63℃, the total SO2 emission reduction rate reached 72.56%, and the coke drying rate was 79%.

[0069] Example 3

[0070] A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove includes the following steps:

[0071] 1) Low-temperature flue gas drying of coke in blast furnace hot blast stove, with primary desulfurization:

[0072] 1-1) Preparation of inhibitor: According to the mass parts, 39 parts of sodium ditridecyl sulfosuccinate, 25 parts of dewaxed kerosene, 15 parts of 4-methyl-2-pentanol, 20 parts of acetone, 14.5 parts of diethyl phthalate (DEP), 10 parts of dodecane, 10 parts of methyl dodecanoate, and 10 parts of n-octanoic acid are mixed and stirred evenly to obtain the inhibitor;

[0073] 1-2) The prepared inhibitor was atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove. The temperature of the low-temperature flue gas was 165℃, the sulfur dioxide concentration was 80.72ppm, and the flue gas flow rate was 150,000 m³ / h. 3 / h, coke (coke parameters are shown in Table 1) was treated with low-temperature flue gas from a blast furnace hot blast stove mixed with atomization inhibitor. The coke moisture content was 8.29%, the amount of inhibitor was 0.89% of the coke mass, the drying time was 2h, and the drying rate was 130t / h. After drying the coke, the liquid and coke powder produced were collected. The temperature of the treated low-temperature flue gas from the blast furnace hot blast stove was 69℃, which was used as tail gas for subsequent secondary desulfurization treatment. The sulfur dioxide concentration in the tail gas was detected to be 40.46ppm. After one desulfurization, the SO2 emission reduction rate was 49.88%.

[0074] 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder for secondary desulfurization:

[0075] 2-1) Preparation of the depressant: According to the mass parts, 30 parts of sodium octadecyl sulfonate, 24.7 parts of sodium dodecylbenzene sulfonate, 20 parts of polyoxyethylene ether fatty alcohol, 14.6 parts of fatty alcohol polyoxyethylene ether sodium sulfate, 20 parts of sodium pyrophosphate, 10 parts of triethanolamine, 10 parts of diethylene glycol butyl ether and 10 parts of sodium hypotriacetate are mixed and stirred evenly to obtain the depressant;

[0076] 2-2) The prepared desulfurizing agent was atomized and mixed into the low-temperature flue gas (tail gas) of the blast furnace hot blast stove after the treatment in step 1) to jointly treat the coke powder produced after drying coke. The amount of desulfurizing agent was 0.98% of the mass ratio of coke powder, the coke powder yield was 10% of the coke mass, and the treatment time was 60s. After the secondary desulfurization, the sulfur dioxide concentration in the flue gas was 7.50ppm, the flue gas temperature was 52℃, the total SO2 emission reduction rate reached 90.71%, and the coke drying rate was 67%.

[0077] Comparative Example 1

[0078] A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove includes the following steps:

[0079] 1) Low-temperature flue gas drying of coke in blast furnace hot blast stove, with primary desulfurization:

[0080] 1-1) Preparation of inhibitor: According to the mass parts, 31 parts of sodium ditridecyl sulfosuccinate, 20 parts of dewaxed kerosene, 10 parts of 4-methyl-2-pentanol (MIBC), 16 parts of acetone, 10.5 parts of diethyl phthalate (DEP), 5.5 parts of dodecane, 6 parts of methyl dodecanoate and 5 parts of n-octanoic acid are mixed and stirred evenly to obtain the inhibitor;

[0081] 1-2) The prepared inhibitor was atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove. The temperature of the low-temperature flue gas was 175℃, the sulfur dioxide concentration was 75.78ppm, and the flue gas flow rate was 150,000 m³ / h. 3 The coke drying capacity is 130 t / h. Coke (coke parameters are shown in Table 1) is treated with low-temperature flue gas from the blast furnace hot blast stove mixed with atomization inhibitor. The coke moisture content is 8.29%, the inhibitor dosage is 0.56% of the coke mass, and the coke drying time is 2 hours. After drying, the liquid and coke powder produced are collected. The temperature of the treated low-temperature flue gas from the blast furnace hot blast stove is 81℃, which is used as tail gas for subsequent secondary desulfurization treatment. The sulfur dioxide concentration in the tail gas is detected to be 50.64 ppm. After primary desulfurization, the SO2 emission reduction rate is 33.17%.

[0082] 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder for secondary desulfurization:

[0083] 2-1) No anti-inhibitor addedThe exhaust gas flow rate is 150,000 m³ / h. 3 / h, the coke powder output is 7.5% of the coke mass (the proportion of coke mass); after the secondary desulfurization, the sulfur dioxide concentration in the flue gas is 50.36ppm, the flue gas temperature is 62℃, the total SO2 emission reduction rate reaches 33.54%, and the coke drying rate is 73%.

[0084] Without the addition of depressant, the coke powder has no ability to adsorb sulfur dioxide.

[0085] Comparative Example 2

[0086] A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove includes the following steps:

[0087] 1) Low-temperature flue gas drying of coke in blast furnace hot blast stove, with primary desulfurization:

[0088] 1-1) Preparation of inhibitor: According to the mass parts, 31 parts of sodium ditridecyl sulfosuccinate, 20 parts of dewaxed kerosene, 10 parts of 4-methyl-2-pentanol (MIBC), 16 parts of acetone, 10.5 parts of diethyl phthalate (DEP), 5.5 parts of dodecane, 6 parts of methyl dodecanoate and 5 parts of n-octanoic acid are mixed and stirred evenly to obtain the inhibitor;

[0089] 1-2) The prepared inhibitor was atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove. The temperature of the low-temperature flue gas was 175℃, the sulfur dioxide concentration was 76.11ppm, and the flue gas flow rate was... 450000m 3 / h, The coke drying capacity was 130 t / h. Coke (coke parameters are shown in Table 1) was treated with low-temperature flue gas from the blast furnace hot blast stove mixed with atomization inhibitor. The coke moisture content was 8.29%, the inhibitor dosage was 0.56% of the coke mass, and the coke drying time was 2 hours. After drying, the liquid and coke powder produced were collected. The temperature of the treated low-temperature flue gas from the blast furnace hot blast stove was 87℃, which was used as tail gas for subsequent secondary desulfurization treatment. The sulfur dioxide concentration in the tail gas was measured to be 54.41 ppm. After primary desulfurization, the SO2 emission reduction rate was 28.51%.

[0090] 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder for secondary desulfurization:

[0091] 2-1) Preparation of the depressant: According to the mass parts, 21 parts of sodium octadecyl sulfonate, 22 parts of sodium dodecylbenzene sulfonate, 15 parts of polyoxyethylene ether fatty alcohol, 11 parts of fatty alcohol polyoxyethylene ether sodium sulfate, 11 parts of sodium pyrophosphate, 6 parts of triethanolamine, 6 parts of diethylene glycol butyl ether, and 3 parts of sodium hypotriacetate are mixed and stirred evenly to obtain the depressant;

[0092] 2-2) The prepared inhibitor is atomized and mixed into the low-temperature flue gas (tail gas) of the blast furnace hot blast stove after step 1) to jointly treat the coke powder produced after drying coke. The amount of inhibitor is 0.68% of the mass ratio of coke powder, and the tail gas flow rate is... 450000m 3 / h The coke powder yield is 7.5% of the coke mass (the percentage of coke mass), and the processing time is 60 seconds. After the secondary desulfurization, the sulfur dioxide concentration in the flue gas is 31.33 ppm, the flue gas temperature is 64℃, the total SO2 emission reduction rate reaches 58.84%, and the coke drying rate is 98%.

[0093] With a large flue gas flow rate, the reaction time between the gas and water / oxygen during the chemical reaction is too short. During physical adsorption, the coke powder cannot fully adsorb sulfur dioxide from the gas, resulting in a low overall emission reduction rate. However, as the flue gas flow rate increases, the moisture in the coke is lost more quickly, increasing the coke's dryness.

[0094] Comparative Example 3

[0095] A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove includes the following steps:

[0096] 1) Low-temperature flue gas drying of coke in blast furnace hot blast stove, with primary desulfurization:

[0097] 1-1) Preparation of inhibitor: According to the mass parts, 31 parts of sodium ditridecyl sulfosuccinate, 20 parts of dewaxed kerosene, 10 parts of 4-methyl-2-pentanol (MIBC), 16 parts of acetone, 10.5 parts of diethyl phthalate (DEP), 5.5 parts of dodecane, 6 parts of methyl dodecanoate and 5 parts of n-octanoic acid are mixed and stirred evenly to obtain the inhibitor;

[0098] 1-2) The prepared inhibitor was atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove. The temperature of the low-temperature flue gas was 175℃, the sulfur dioxide concentration was 75.65ppm, and the flue gas flow rate was 150,000 m³ / h. 3 The coke drying capacity is 130 t / h. Coke is treated with low-temperature flue gas from the blast furnace hot blast stove mixed with atomization inhibitor. The coke moisture content is 1.23%, the inhibitor dosage is 0.56% of the coke mass, and the coke drying time is 2 hours. After drying, the liquid and coke powder produced are collected. The temperature of the treated low-temperature flue gas from the blast furnace hot blast stove is 85℃, which is used as tail gas for subsequent secondary desulfurization treatment. The sulfur dioxide concentration in the tail gas is detected to be 61.10 ppm. After primary desulfurization, the SO2 emission reduction rate is 19.23%.

[0099] 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder for secondary desulfurization:

[0100] 2-1) Preparation of the depressant: According to the mass parts, 21 parts of sodium octadecyl sulfonate, 22 parts of sodium dodecylbenzene sulfonate, 15 parts of polyoxyethylene ether fatty alcohol, 11 parts of fatty alcohol polyoxyethylene ether sodium sulfate, 11 parts of sodium pyrophosphate, 6 parts of triethanolamine, 6 parts of diethylene glycol butyl ether, and 3 parts of sodium hypotriacetate are mixed and stirred evenly to obtain the depressant;

[0101] 2-2) The prepared inhibitor is atomized and mixed into the low-temperature flue gas (tail gas) of the blast furnace hot blast stove after the treatment in step 1) to jointly treat the coke powder produced after drying coke. The amount of inhibitor is 0.68% of the mass ratio of coke powder, and the tail gas flow rate is 150,000 m³ / h. 3 / h, the coke powder output is 7.5% of the coke mass (the percentage of coke mass), the processing time is 60s; after the secondary desulfurization, the sulfur dioxide concentration in the flue gas is 25.39ppm, the flue gas temperature is 60℃, the total SO2 emission reduction rate reaches 66.44%, and the coke drying rate is 70%.

[0102] Comparative Example 4

[0103] A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove includes the following steps:

[0104] 1) Low-temperature flue gas drying of coke in blast furnace hot blast stove, with primary desulfurization:

[0105] 1-1) Preparation of inhibitor: According to the mass parts, 31 parts of sodium ditridecyl sulfosuccinate, 20 parts of dewaxed kerosene, 10 parts of 4-methyl-2-pentanol (MIBC), 16 parts of acetone, 10.5 parts of diethyl phthalate (DEP), 5.5 parts of dodecane, 6 parts of methyl dodecanoate and 5 parts of n-octanoic acid are mixed and stirred evenly to obtain the inhibitor;

[0106] 1-2) The prepared inhibitor is atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove. The temperature of the low-temperature flue gas in the blast furnace hot blast stove is 175℃, and the sulfur dioxide concentration is [missing information]. 1500.14ppm The flue gas flow rate is 150,000 m³. 3 The coke drying capacity is 130 t / h. Coke (coke parameters are shown in Table 1) is treated with low-temperature flue gas from the blast furnace hot blast stove mixed with atomization inhibitor. The coke moisture content is 8.29%, the inhibitor dosage is 0.56% of the coke mass, and the coke drying time is 2 hours. After drying, the liquid and coke powder produced are collected. The temperature of the treated low-temperature flue gas from the blast furnace hot blast stove is 79℃, which is used as tail gas for subsequent secondary desulfurization treatment. The sulfur dioxide concentration in the tail gas is 1417.48 ppm. After primary desulfurization, the SO2 emission reduction rate is 5.51%.

[0107] 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder for secondary desulfurization:

[0108] 2-1) Preparation of the depressant: According to the mass parts, 21 parts of sodium octadecyl sulfonate, 22 parts of sodium dodecylbenzene sulfonate, 15 parts of polyoxyethylene ether fatty alcohol, 11 parts of fatty alcohol polyoxyethylene ether sodium sulfate, 11 parts of sodium pyrophosphate, 6 parts of triethanolamine, 6 parts of diethylene glycol butyl ether, and 3 parts of sodium hypotriacetate are mixed and stirred evenly to obtain the depressant;

[0109] 2-2) The prepared inhibitor is atomized and mixed into the low-temperature flue gas (tail gas) of the blast furnace hot blast stove after the treatment in step 1) to jointly treat the coke powder produced after drying coke. The amount of inhibitor is 0.68% of the mass ratio of coke powder, and the tail gas flow rate is 150,000 m³ / h. 3 / h, the coke powder output is 7.5% of the coke mass (the percentage of coke mass), the processing time is 60s; after the secondary desulfurization, the sulfur dioxide concentration in the flue gas is 1263.27ppm, the flue gas temperature is 60℃, the total SO2 emission reduction rate reaches 15.79%, and the coke drying rate is 75%.

[0110] The concentration of sulfur dioxide was 1500.14 ppm, the concentration is too high, leading to... SO2 emission reduction rate is low.

[0111] Comparative Example 5

[0112] A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove includes the following steps:

[0113] 1-1) Preparation of inhibitor: According to the mass parts, 20 parts of dewaxed kerosene, 10 parts of 4-methyl-2-pentanol (MIBC), 16 parts of acetone, 10.5 parts of diethyl phthalate (DEP), 5.5 parts of dodecane, 6 parts of methyl dodecanoate and 5 parts of n-octanoic acid are mixed and stirred evenly to obtain the inhibitor. Compared to Example 1, it does not contain 31 parts of sodium ditridecyl sulfosuccinate.

[0114] 1-2) The prepared inhibitor was atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove. The temperature of the low-temperature flue gas was 175℃, the sulfur dioxide concentration was 75.56ppm, and the flue gas flow rate was 150,000 m³ / h. 3 / h, the low-temperature flue gas from the blast furnace hot blast stove is used to treat coke (coke indicators are shown in Table 1). The coke moisture content is 8.29%, and the amount of inhibitor used is 0.56% of the coke mass (inhibitors that do not meet the requirements). The coke drying time is 2h. After drying the coke, the liquid produced during the drying process is collected, and the coke powder produced is also collected. The temperature of the treated low-temperature flue gas from the blast furnace hot blast stove is 82℃. This gas is used as tail gas for subsequent secondary desulfurization treatment. The sulfur dioxide concentration in the tail gas is 50.49ppm. After one desulfurization, the SO2 emission reduction rate is 33.18%.

[0115] 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder for secondary desulfurization:

[0116] 2-1) Preparation of the depressant: According to the mass parts, 21 parts of sodium octadecyl sulfonate, 22 parts of sodium dodecylbenzene sulfonate, 15 parts of polyoxyethylene ether fatty alcohol, 11 parts of fatty alcohol polyoxyethylene ether sodium sulfate, 11 parts of sodium pyrophosphate, 6 parts of triethanolamine, 6 parts of diethylene glycol butyl ether, and 3 parts of sodium hypotriacetate are mixed and stirred evenly to obtain the depressant;

[0117] 2-2) The prepared desulfurizing agent was atomized and mixed with the coke powder produced after drying coke from the low-temperature flue gas (tail gas) of the blast furnace hot blast stove treated in step 1). The amount of desulfurizing agent was 0.68% of the mass ratio of coke powder, the coke powder yield was 7.5% of the coke mass, and the treatment time was 60s. After the secondary desulfurization, the sulfur dioxide concentration in the flue gas was 24.37ppm, the flue gas temperature was 61℃, the total SO2 emission reduction rate reached 67.75%, and the coke drying rate was 74%.

[0118] Sodium ditridecyl sulfosuccinate is a high-performance, oil-soluble, hydrophobic surfactant. Removing sodium ditridecyl sulfosuccinate from the inhibitor prevents synergistic effects with other reagents, directly leading to inhibitor inactivation. The inhibitor in this comparative sample does not meet the requirements, leaving sulfur dioxide in the coke. Since coke powder is generated from wear during transport, sulfur dioxide is already present in the coke powder, resulting in a decrease in emission reduction rate.

[0119] Comparative Example 6

[0120] A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove includes the following steps:

[0121] 1) Low-temperature flue gas drying of coke in blast furnace hot blast stove, with primary desulfurization:

[0122] 1-1) Preparation of inhibitor: According to the mass parts, 31 parts of sodium ditridecyl sulfosuccinate, 20 parts of dewaxed kerosene, 10 parts of 4-methyl-2-pentanol (MIBC), 16 parts of acetone, 10.5 parts of diethyl phthalate (DEP), 5.5 parts of dodecane, 6 parts of methyl dodecanoate and 5 parts of n-octanoic acid are mixed and stirred evenly to obtain the inhibitor;

[0123] 1-2) The prepared inhibitor was atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove. The temperature of the low-temperature flue gas was 175℃, the sulfur dioxide concentration was 76.11ppm, and the flue gas flow rate was 150,000 m³ / h. 3 / h, the low-temperature flue gas from the blast furnace hot blast stove is used to treat coke (coke parameters are shown in Table 1). The coke moisture content is 8.29%, the amount of inhibitor is 0.56% of the coke mass, and the coke drying time is 2h. After drying the coke, the liquid produced during the drying process is collected, and the coke powder produced is also collected. The temperature of the treated low-temperature flue gas from the blast furnace hot blast stove is 80℃, which is used as tail gas for subsequent secondary desulfurization treatment. The sulfur dioxide concentration in the tail gas was detected to be 51.34ppm. After one desulfurization, the SO2 emission reduction rate is 32.55%.

[0124] 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder for secondary desulfurization:

[0125] 2-1) Preparation of anti-inhibitor: According to the mass parts, 15 parts of polyoxyethylene ether fatty alcohol, 11 parts of fatty alcohol polyoxyethylene ether sodium sulfate, 11 parts of sodium pyrophosphate, 6 parts of triethanolamine, 6 parts of diethylene glycol butyl ether, and 3 parts of sodium hypotriacetate are mixed and stirred evenly to obtain the anti-inhibitor. Compared to Example 1, it does not contain 21 parts of sodium octadecyl sulfonate or 22 parts of dodecyl sulfate. Sodium benzenesulfonate.

[0126] 2-2) The prepared desulfurizing agent is atomized and mixed with the coke powder produced after drying coke from the low-temperature flue gas (tail gas) of the blast furnace hot blast stove treated in step 1). The amount of desulfurizing agent is 0.68% of the mass ratio of coke powder (desulfurizing agent that does not meet the requirements), the coke powder yield is 7.5% of the coke mass, and the treatment time is 60s. After the secondary desulfurization, the sulfur dioxide concentration in the flue gas is 43.75ppm, the flue gas temperature is 62℃, the total SO2 emission reduction rate reaches 42.52%, and the coke drying rate is 72%.

[0127] Sodium octadecyl sulfonate and sodium dodecylbenzene sulfonate can destroy hydrocarbon oils and esters, disrupting the liquid barrier layer formed by inhibitors. Inadequate inhibitors fail to completely neutralize the inhibitor's effect, directly resulting in the presence of some effective inhibitors in the coke powder, leading to extremely poor physical adsorption of sulfur dioxide.

[0128] This invention utilizes low-grade hot blast stove waste gas after passing through a heat exchanger to dry coke, without consuming additional fuel, achieving waste heat utilization, reducing the coke ratio, and improving the comprehensive utilization rate of waste energy in the ironmaking system. This technology integrates coke drying and flue gas desulfurization, with simple equipment, low construction costs, and high returns.

[0129] The items underlined above do not meet the requirements of this invention.

[0130] The above detailed description of a method for desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove, as described in the reference embodiments, is illustrative rather than limiting. Several embodiments can be listed within the defined scope. Therefore, variations and modifications that do not depart from the overall concept of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for synergistic desulfurization using waste heat from low-temperature flue gas in a blast furnace hot blast stove, characterized in that, The method includes the following steps: 1) Low-temperature flue gas from the blast furnace hot blast stove dries coke and performs primary desulfurization; 2) The low-temperature flue gas from the blast furnace hot blast stove after step 1) is treated with coke powder for secondary desulfurization; In step 1), the coke is coke treated with an inhibitor; the inhibitor is prepared from the following raw materials in parts by weight: 30-40 parts sodium ditridecyl sulfosuccinate, 20-25 parts dewaxed kerosene, 10-15 parts 4-methyl-2-pentanol, 15-20 parts acetone, 10-15 parts diethyl phthalate, 5-10 parts dodecane, 5-10 parts methyl dodecanoate, and 5-10 parts octanoic acid.

2. The method according to claim 1, characterized in that, In step 1), the temperature of the low-temperature flue gas in the blast furnace hot blast stove is 130-190℃.

3. The method according to claim 1, characterized in that, In step 1), the inhibitor is atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove to dry the coke.

4. The method according to claim 1 or 3, characterized in that, In step 1), the amount of inhibitor used is 0.2%-1.0% of the coke mass.

5. The method according to claim 1, characterized in that, In step 2), the coke powder is treated with an inhibitor; the inhibitor is prepared from the following raw materials in parts by weight: 20-30 parts sodium octadecyl sulfonate, 20-25 parts sodium dodecylbenzene sulfonate, 15-20 parts polyoxyethylene ether fatty alcohol, 10-15 parts sodium fatty alcohol polyoxyethylene ether sulfate, 10-20 parts sodium pyrophosphate, 5-10 parts triethanolamine, 5-10 parts diethylene glycol butyl ether, and 2-10 parts sodium hypotriacetate.

6. The method according to claim 5, characterized in that, In step 2), the inhibitor is atomized and mixed into the low-temperature flue gas of the blast furnace hot blast stove after being treated in step 1), and then treated with coke powder.

7. The method according to claim 5 or 6, characterized in that, In step 2), the amount of the depressant is 0.3%-1.5% of the mass of the coke powder.

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