Steel slag as desulfurizer rolling heating furnace dry desulfurization device and method

Abstract

The present application relates to a kind of steel slag as desulfurizer steel rolling heating furnace dry desulfurization device and method, including heating furnace flue, air heat exchanger, gas heat exchanger, chimney, the heating furnace flue is communicated chimney, air heat exchanger and flue gas heat exchanger are arranged in heating furnace flue, before air heat exchanger and flue gas heat exchanger, install desulfurization device, the desulfurization device includes desulfurization device support frame, desulfurizer loading pipe, sealing element, desulfurizer, installation hole is equipped in the upper end of the heating furnace flue, the desulfurization device support frame is fixed in the heating furnace flue of installation hole bottom, the desulfurizer is filled in desulfurizer loading pipe, the desulfurizer loading pipe is inserted in desulfurization device support frame, the desulfurizer loading pipe upper end is filled with sealing element.The present application provides reasonable reaction temperature and reaction time by using steel rolling heating furnace waste heat, to further realize the high efficiency dry desulfurization of steel slag as desulfurizer in true sense.

Description

Technical Field

[0001] This invention belongs to the field of thermal energy conservation, and specifically relates to a dry desulfurization device and method for a steel rolling heating furnace using steel slag as a desulfurizing agent. Background Technology

[0002] Environmental issues are currently the primary constraint on the development of the steel industry. Sulfur and nitrogen in raw materials and fuels are converted into gases or liquids through combustion and chemical reactions, entering the environment and causing damage, and are major causes of disasters such as acid rain. Currently, desulfurization technologies both domestically and internationally are mainly divided into two categories: sulfur control technologies during production and desulfurization treatment of waste materials after production. Generally, process-controlled desulfurization rates are low, reaching only around 50%, which cannot meet the requirements for ultra-low emissions. While waste desulfurization technologies, such as XRD and activated carbon methods, have higher removal rates, their high operating costs and demanding reaction conditions significantly increase the costs of the steel industry, severely restricting its development.

[0003] Patent document CN202310517325.6 discloses a waste gas sintering method for steel slag desulfurization. The device includes a slag crushing unit and a desulfurization and dust removal unit. The desulfurization and dust removal unit includes a chamber shell with a flue gas duct and a mixing and stirring device installed inside the flue gas duct. A multi-hole passive nozzle, connected to the outlet of the mixing and stirring device, is perforated through the wall of the flue gas duct. The process includes: the slag crushing unit crushes steel slag into slag powder and transports it to the crushing unit to form a slag powder slurry; the slag powder slurry is drawn into the flue gas duct by high-speed flow of sulfur-containing flue gas through the multi-hole passive nozzle. By utilizing the high-speed flow of flue gas in the flue gas duct to attract the slag powder slurry into the flue gas duct, energy saving is achieved. Furthermore, the flue gas carrying the slag powder slurry in the flue gas duct further diffuses upon entering the chamber shell, facilitating mixing between the flue gas and the slag powder slurry, thereby improving the desulfurization effect on the flue gas.

[0004] Patent document CN202322443421.9 discloses an apparatus for preparing steel slag desulfurization slurry, comprising: a primary slurry preparation system, a slurry external circulation system, a screw conveyor, a waste silo, a slurry overflow pipe, and a secondary slurry preparation system. The primary slurry preparation system is used for preparing the steel slag desulfurization slurry, and the secondary slurry preparation system is used to supplement the prepared steel slag desulfurization slurry with calcium necessary for the desulfurization reaction. The apparatus provided by this invention can ensure the stability and continuity of the overall desulfurization process system.

[0005] Patent document CN201610614300.8 discloses a steel slag-based modified desulfurizing agent for wet desulfurization and its preparation method. The steel slag-based modified desulfurizing agent comprises the following components by weight: steel slag (92.0–99.0) parts and phosphoric acid (1.0–8.0) parts. Using the desulfurizing agent described in this invention not only turns waste into treasure but also achieves high desulfurization efficiency, making it both environmentally friendly and improving energy utilization.

[0006] Steel slag, a major waste product of the steel industry, is primarily composed of metal oxides. Chemically, it can be used as a desulfurizing agent. Current technologies using steel slag as a desulfurizing agent primarily employ wet desulfurization, which involves grinding the slag to form a slurry, increasing the reaction rate between SO2 in the exhaust gas and the desulfurizing components in the slag. However, this process generates sulfur-containing saturated steam and wastewater, potentially leading to the formation of harmful secondary substances. Furthermore, the high cost of steel slag grinding hinders cost reduction. From a chemical reaction perspective, temperature significantly promotes the reaction intensity between SO2 and metal oxides such as CaO. This invention utilizes the waste heat from the steel rolling furnace to provide a suitable reaction temperature and time, thereby achieving truly efficient dry desulfurization using steel slag as a desulfurizing agent. Summary of the Invention

[0007] The purpose of this invention is to provide a dry desulfurization device and method for a steel rolling mill heating furnace using steel slag as a desulfurizing agent. This invention utilizes the waste heat of the steel rolling mill heating furnace to provide a reasonable reaction temperature and reaction time, thereby achieving truly efficient dry desulfurization using steel slag as a desulfurizing agent.

[0008] To achieve the above objectives, the present invention employs the following technical solution: A dry desulfurization device for a steel rolling mill heating furnace using steel slag as a desulfurizing agent includes a heating furnace flue, an air heat exchanger, a gas heat exchanger, and a chimney. The heating furnace flue is connected to the chimney. The air heat exchanger and the gas heat exchanger are arranged in the heating furnace flue. A desulfurization device is installed before the air heat exchanger and the gas heat exchanger. The desulfurization device includes a desulfurization device support frame, a desulfurizing agent receiving pipe, a sealing element, and a desulfurizing agent. An installation hole is provided at the upper end of the heating furnace flue. The desulfurization device support frame is fixed in the heating furnace flue at the bottom of the installation hole. The desulfurizing agent is filled in the desulfurizing agent receiving pipe, which is inserted into the desulfurization device support frame. The upper end of the desulfurizing agent receiving pipe is filled with a sealing element.

[0009] The desulfurizing agent is steel slag with an oxide content greater than 50% that has been crushed, and the particle size of the steel slag is 2-25mm.

[0010] The sealing element is a high-temperature resistant fiber blanket or rock wool.

[0011] The desulfurization device is arranged in a multi-row, multi-column structure in the heating furnace flue, with the rows arranged in a staggered manner.

[0012] A hoisting device is provided at the upper end of the desulfurizing agent receiving pipe.

[0013] Both the desulfurizing agent container pipe and the desulfurization device support frame are mesh-like, and the nominal diameter of the mesh is smaller than the minimum particle size of the desulfurizing agent.

[0014] The air exchanged in the air heat exchanger is the combustion air for the heating furnace, and the gas exchanged in the gas heat exchanger is the fuel gas for the heating furnace.

[0015] The equivalent diameter of the desulfurizing agent container pipe is between 50 and 200 mm.

[0016] A method for using a dry desulfurization device for a steel rolling furnace with steel slag as a desulfurizing agent includes: 1) The temperature of the high-temperature flue gas in the heating furnace flue shall not be lower than 750℃.

[0017] 2) The total amount of steel slag charged is calculated based on the flue gas volume of the heating furnace and the total amount of harmful components in the flue gas, while also taking into account the operating time of the desulfurization unit. The calculation method is as follows:

[0018] Where: G 脱硫剂 Total weight of desulfurizer during the usage cycle, t / cycle; Vy: Average smoke emission during the service life, Nm 3 / h; φ(SO2): Average SO2 content in flue gas, mg / Nm³ 3 ; τ: The duration of the usage cycle, in hours; φ （金属氧化物） : The proportion of metal oxides in steel slag, %.

[0019] 3) To ensure sufficient reaction between SO2 in the flue gas and metal oxides in the steel slag, the equivalent diameter of the desulfurizing agent container pipe should not be too large. A multi-row, multi-column structure should be adopted, with staggered arrangements between rows. The pipe spacing should be the same as the diameter of the desulfurizing agent container pipe, and the number of pipe columns per row should be:

[0020] Where: m: number of desulfurizing agent loading pipes per row, pipes / row; W: Inner width of the flue, in meters; D: Equivalent diameter of the desulfurizing agent container pipe, in meters.

[0021] 4) The number of rows of desulfurizing agent storage pipes is based on the total weight of the desulfurizing agent (G) during the service life. 脱硫剂Divide by the amount loaded per row, and the specific calculation formula is as follows:

[0022] In the formula: n: number of rows of desulfurizing agent container pipes; ρ 渣 Bulk density of steel slag as a desulfurizing agent; kg / m³ 3 ; H: Height inside the flue, in meters (m).

[0023] Compared with the prior art, the beneficial effects of the present invention are: This invention proposes a dry desulfurization device and method for a steel rolling furnace using steel slag as a desulfurizing agent. The device utilizes the reaction of steel slag metal oxides with SO2 in the flue gas at high temperature, thereby increasing the desulfurization rate by more than 50% while significantly reducing the desulfurization cost of steel plants. Attached Figure Description

[0024] Figure 1 This is an overall schematic diagram of the dry desulfurization device for a steel rolling heating furnace using steel slag as a desulfurizing agent according to the present invention.

[0025] Figure 2 This is a partial cross-sectional view of the desulfurization unit.

[0026] Figure 3 This is a schematic diagram of the desulfurizing agent container pipe.

[0027] In the diagram: 1. Heating furnace flue inlet; 2. Heating furnace flue; 3. Desulfurization device; 4. Air heat exchanger; 5. Gas heat exchanger; 6. Chimney; 7. Flue refractory layer; 8. Mounting hole; 9. Desulfurization device support frame; 10. Sealing element; 11. Lifting equipment; 12. Desulfurizing agent container pipe. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the specific implementation methods of this invention will be further described below in conjunction with the embodiments. The following embodiments are used to specifically illustrate the content of this invention. These embodiments are only general descriptions of the content of this invention and do not limit the content of this invention.

[0029] See Figures 1-3A dry desulfurization device for a steel rolling mill heating furnace using steel slag as a desulfurizing agent includes a heating furnace flue 2, an air heat exchanger 4, a gas heat exchanger 5, and a chimney 6. The heating furnace flue 2 is connected to the chimney 6. The air heat exchanger 4 and the gas heat exchanger 5 are arranged in the heating furnace flue 2. A desulfurization device 3 is installed before the air heat exchanger 4 and the gas heat exchanger 5. The desulfurization device 3 includes a desulfurization device support frame 9, a desulfurizing agent receiving pipe 12, a sealing element 10, and a desulfurizing agent. An installation hole 8 is provided at the upper end of the heating furnace flue 2. The desulfurization device support frame 9 is fixed in the heating furnace flue 2 at the bottom of the installation hole 8. The desulfurizing agent is filled in the desulfurizing agent receiving pipe 12, which is inserted into the desulfurization device support frame 9. The upper end of the desulfurizing agent receiving pipe 12 is filled with a sealing element 10.

[0030] The desulfurizing agent is steel slag with an oxide content greater than 50% that has been crushed, and the particle size of the steel slag is 2-25 mm.

[0031] The sealing element 10 is a high-temperature resistant fiber blanket or rock wool.

[0032] The desulfurization device 3 is arranged in a multi-row, multi-column structure in the heating furnace flue 2, with the rows arranged in a staggered manner.

[0033] A hoisting device 11 is provided at the upper end of the desulfurizing agent receiving pipe 12.

[0034] Both the desulfurizing agent container pipe 12 and the desulfurization device support frame 9 are mesh-like, and the nominal diameter of the mesh is smaller than the minimum particle size of the desulfurizing agent.

[0035] The air exchanged in the air heat exchanger 4 is the combustion air for the heating furnace, and the gas exchanged in the gas heat exchanger 5 is the fuel gas for the heating furnace.

[0036] The equivalent diameter of the desulfurizing agent container pipe 12 is between 50 and 200 mm.

[0037] A method for using a dry desulfurization device for a steel rolling furnace with steel slag as a desulfurizing agent includes: 1) To ensure desulfurization efficiency and desulfurization reaction time, and at the same time reduce the formation of CaCO3, the temperature of the high-temperature flue gas in the heating furnace flue 2 shall not be lower than 750℃.

[0038] 2) The total amount of steel slag charged is calculated based on the flue gas volume of the heating furnace and the total amount of harmful components in the flue gas, while also taking into account the operating time of the desulfurization unit. The calculation method is as follows:

[0039] Where: G 脱硫剂 Total weight of desulfurizer during the usage cycle, t / cycle; Vy: Average smoke emission during the service life, Nm3 / h; φ(SO2): Average SO2 content in flue gas, mg / Nm³ 3 ; τ: The duration of the usage cycle, in hours; φ （金属氧化物） : The proportion of metal oxides in steel slag.

[0040] 3) To ensure sufficient reaction between SO2 in the flue gas and metal oxides in the steel slag, the equivalent diameter of the desulfurizing agent container pipe 12 should not be too large. A multi-row, multi-column structure should be adopted, with staggered arrangements between rows. The pipe spacing should be the same as the diameter of the desulfurizing agent container pipe 12. The number of pipe columns per row is:

[0041] Where: m: number of desulfurizing agent loading pipes per row, pipes / row; W: Inner width of the flue, in meters; D: Equivalent diameter of the desulfurizing agent container pipe, in meters.

[0042] 4) The number of rows of desulfurizing agent storage pipes is based on the total weight of the desulfurizing agent (G) during the service life. 脱硫剂 Divide by the amount loaded per row, and the specific calculation formula is as follows:

[0043] Where: n: number of rows of desulfurizing agent container pipes; ρ 渣 Bulk density of steel slag as a desulfurizing agent; kg / m³ 3 ; H: Height inside the flue, in meters (m).

[0044] See Figure 1 Conventional heating furnaces lack desulfurization devices 3 in their exhaust systems. High-temperature flue gas generated during combustion within the furnace enters the furnace flue duct 2 through the furnace inlet 1. After passing through the air heat exchanger 4 and the gas heat exchanger 5, the high-temperature flue gas exchanges heat with the air and gas, transforming into low-temperature waste gas, which is then discharged from the heating furnace system through the chimney 6. This invention adds n rows and m columns of desulfurization devices 3 between the furnace flue inlet 1 and the air heat exchanger 4. The high temperature of the flue gas catalyzes the reaction between metal oxides in the steel slag and SO2 components in the flue gas, while simultaneously inhibiting the reaction between CO2 and metal oxides in the flue gas, achieving efficient dry desulfurization. The desulfurization device 3 consists of two parts; the internal structure is shown in the attached diagram. Figure 2 An opening is made at the top of the refractory layer 7 of the flue gas duct 2 before the air heat exchanger 4. The opening shape can be circular, square, triangular, or other shapes. A desulfurization device support frame 9 is installed through the mounting holes 8 to support the desulfurization device. The support frame is made of high-temperature corrosion-resistant steel and can be a mesh column or other structural shape. See the attached diagram for the external structure of the desulfurization device. Figure 3The desulfurizing agent receiving pipe 12 is inserted into the desulfurization device support frame 9. The desulfurizing agent receiving pipe 12 has a mesh column structure with a cross-sectional shape consistent with the mounting hole 8. The nominal diameter is 2-10 mm smaller than the mounting hole to facilitate installation. The bottom of the desulfurizing agent receiving pipe 12 contacts the flue refractory layer 7 and is 10-50 mm higher than the outside of the flue. The material is high-temperature corrosion-resistant steel or other high-temperature oxidation-resistant metals or non-metals. The nominal diameter of the mesh is smaller than the minimum particle size of the desulfurizing agent. A hoisting device 11 is installed on the top of the desulfurizing agent receiving pipe 12.

[0045] The desulfurizing agent of this invention uses waste steel slag from steelmaking. After crushing, steel slag with a diameter of 5-25mm is screened out as the desulfurizing agent. It is loaded into the desulfurizing agent receiving pipe 12, with the loading height being the same as the inner height of the flue refractory layer 7. The sealing part 10 is filled with high-temperature resistant fiber blanket or rock wool for sealing. The desulfurizing agent receiving pipe 12 filled with desulfurizing agent and high-temperature resistant fiber blanket or rock wool is installed into the desulfurization device support frame 9 using the hoisting equipment 11. The gap between the installation hole 8 and the desulfurizing agent receiving pipe 12 is further sealed with refractory and high-temperature resistant fiber blanket or rock wool. The metal oxides in the steel slag in the desulfurizing agent receiving pipe 12 remove SO2 from the high-temperature flue gas and generate stable CaSO4 in the aerobic environment of the flue gas. At the same time, the high-temperature environment greatly improves the removal rate and effectively inhibits the formation of CaCO3, thus greatly improving the service life of the desulfurizing agent.

[0046] The desulfurizing agent can be converter slag, refining slag, or other steel slag waste with more than 50% metal oxides.

[0047] Example 1:

[0048] A wire heating furnace in a certain factory uses 2000Kcal / Nm³. 3 The mixed gas is used as fuel, with a gas volume of 20,000 Nm³. 3 / h, normal production exhaust volume 62500Nm 3 / h, flue internal width 6.7m, internal height 3m, current flue gas SO2 content 100mg / Nm³ 3 It meets current environmental protection standards but does not meet ultra-low emission standards. According to this method, converter slag is used as a desulfurizing agent, with a steel slag bulk density of 2100 kg / m³. 3 The steel slag has a metal oxide content of 70%. Based on a 3-month operating time and a desulfurizer usage cycle of 2100 hours, achieving ultra-low emissions requires the removal of 5.28 tons of SO2 and 5.70 tons of desulfurizer. Using 100mm diameter circular pipes as the support frame for the desulfurization unit, 136 desulfurization mounting pipes are required, arranged in four rows of 34 pipes each, staggered along the horizontal flue. When the flue gas temperature stabilizes at around 800℃, an SO2 content of 48 mg / Nm³ can be achieved in the flue gas emissions. 3The desulfurization rate is increased by more than 52%, meeting the national ultra-low emission standards. At the same time, the treated steel slag has stable properties and the content of free calcium oxide and magnesium oxide is greatly reduced, enabling rapid further resource utilization.

[0049] Example 2:

[0050] A certain factory's plate heating furnace uses 4000Kcal / Nm³ 3 The mixed gas is used as fuel, with a gas volume of 18000 Nm³. 3 / h, normal production exhaust volume 98500Nm 3 / h, the flue has an internal width of 13m and an internal height of 3m, and the current SO2 content in the flue gas is 80mg / Nm³. 3 It meets current environmental standards but does not meet ultra-low emission standards. According to this method, the steel slag has a metal oxide content of 80% and a bulk density of 1900 kg / m³. 3 Designed for a 4-month operating period (2800 hours) of desulfurizing agent usage, achieving ultra-low emissions requires the removal of 10.58 tons of SO2 and 11.58 tons of desulfurizing agent. Using 100mm diameter circular pipes as the receiving pipes, 260 desulfurization receiving pipes are needed, arranged in four rows of 65 pipes each, staggered along the horizontal flue. When the flue gas temperature stabilizes at around 850℃, an SO2 content of 32 mg / Nm³ in the flue gas emissions can be achieved. 3 The desulfurization rate is increased by more than 68%, meeting the national ultra-low emission standards. At the same time, the treated steel slag has stable properties and the content of free calcium oxide and magnesium oxide is greatly reduced, enabling rapid further resource utilization.

Claims

1. A dry desulfurization device for a steel rolling mill heating furnace using steel slag as a desulfurizing agent, comprising a heating furnace flue, an air heat exchanger, a gas heat exchanger, and a chimney, wherein the heating furnace flue is connected to the chimney, and the air heat exchanger and the gas heat exchanger are disposed within the heating furnace flue, characterized in that, A desulfurization device is installed before the air heat exchanger and the gas heat exchanger. The desulfurization device includes a desulfurization device support frame, a desulfurizing agent receiving pipe, a sealing element, and a desulfurizing agent. An installation hole is provided at the upper end of the heating furnace flue. The desulfurization device support frame is fixed in the heating furnace flue at the bottom of the installation hole. The desulfurizing agent is filled in the desulfurizing agent receiving pipe, which is inserted into the desulfurization device support frame. A sealing element is filled at the upper end of the desulfurizing agent receiving pipe. The desulfurizing agent is steel slag with an oxide content greater than 50% that has been crushed, and the particle size of the steel slag is 2-25 mm.

2. The dry desulfurization device for a steel rolling furnace using steel slag as a desulfurizing agent according to claim 1, characterized in that, The sealing element is a high-temperature resistant fiber blanket or rock wool.

3. The dry desulfurization device for a steel rolling furnace using steel slag as a desulfurizing agent according to claim 1, characterized in that, The desulfurization device is arranged in a multi-row, multi-column structure in the heating furnace flue, with the rows arranged in a staggered manner.

4. A dry desulfurization device for a steel rolling furnace using steel slag as a desulfurizing agent according to claim 1, characterized in that, A hoisting device is provided at the upper end of the desulfurizing agent receiving pipe.

5. A dry desulfurization device for a steel rolling furnace using steel slag as a desulfurizing agent according to claim 1, characterized in that, Both the desulfurizing agent container pipe and the desulfurization device support frame are mesh-like, and the nominal diameter of the mesh is smaller than the minimum particle size of the desulfurizing agent.

6. A dry desulfurization device for a steel rolling furnace using steel slag as a desulfurizing agent according to claim 1, characterized in that, The air exchanged in the air heat exchanger is the combustion air for the heating furnace, and the gas exchanged in the gas heat exchanger is the fuel gas for the heating furnace.

7. A dry desulfurization device for a steel rolling furnace using steel slag as a desulfurizing agent according to claim 1, characterized in that, The equivalent diameter of the desulfurizing agent container pipe is between 50 and 200 mm.

8. A method of using a dry desulfurization device for a steel rolling furnace as a desulfurizing agent, as described in any one of claims 1-7, characterized in that, include: 1) The temperature of the high-temperature flue gas in the heating furnace flue shall not be lower than 750℃; 2) The total amount of steel slag charged is calculated based on the flue gas volume of the heating furnace and the total amount of harmful components in the flue gas, while also taking into account the operating time of the desulfurization unit. The calculation method is as follows: Where: G 脱硫剂 Total weight of desulfurizer during the usage period, in tons; Vy: Average smoke emission during the service life, Nm 3 / h; φ(SO2): Average SO2 content in flue gas, mg / Nm³ 3 ; τ: The duration of the usage cycle, in hours; φ （金属氧化物） The proportion of metal oxides in steel slag, % 3) The pipe spacing of the desulfurizing agent receiving pipe is the same as the diameter of the desulfurizing agent receiving pipe, and the number of pipe columns in each row is: Where: m: number of desulfurizing agent loading pipes per row, pipes / row; W: Inner width of the flue, in meters; D: Equivalent diameter of the desulfurizing agent container pipe, in meters; 4) The number of rows of desulfurizing agent storage pipes is based on the total weight of the desulfurizing agent (G) during the service life. 脱硫剂 Divide by the amount loaded per row, and the specific calculation formula is as follows: Where: n: number of rows of desulfurizing agent container pipes; ρ 渣 Bulk density of steel slag as a desulfurizing agent; kg / m³ 3 ; H: Height inside the flue, in meters (m).

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