Dry desulfurization device and method for steel rolling heating furnace with steel slag as desulfurizer

Abstract

The invention relates to a dry-type desulfurization device and method for a steel rolling heating furnace with steel slag as a desulfurizer, the dry-type desulfurization device comprises a heating furnace flue, an air heat exchanger, a gas heat exchanger and a chimney, the heating furnace flue is communicated with the chimney, and the air heat exchanger and the gas heat exchanger are arranged in the heating furnace flue; a desulfurization device is mounted in front of the air heat exchanger and the flue gas heat exchanger, the desulfurization device comprises a desulfurization device support frame, a desulfurizer bearing pipe, a sealing element and a desulfurizer, a mounting hole is formed in 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 mounting hole, and the desulfurizer bearing pipe is fixed in the mounting hole. The desulfurizer is filled in the desulfurizer containing pipe, the desulfurizer containing pipe is inserted into the desulfurizer supporting frame, and the upper end of the desulfurizer containing pipe is filled with a sealing piece. According to the method, reasonable reaction temperature and reaction time are provided by utilizing the waste heat of the steel rolling heating furnace, so that efficient dry desulfurization taking the steel slag as the desulfurizing agent in a real sense is realized.

Description

Technical Field

[0001] The present invention belongs to the field of thermal energy conservation, and in particular relates to a dry desulfurization device and method for a steel rolling heating furnace using steel slag as a desulfurizer. Background Art

[0002] Environmental issues are currently the primary constraint on the development of the steel industry. Sulfur and nitrogen in raw materials are converted into gases or liquids through combustion and chemical reactions, entering the environment and causing environmental damage. They are a major cause of disasters such as acid rain. Current desulfurization technologies, both domestically and internationally, fall into two main categories: sulfur control during production and post-production waste desulfurization. Generally speaking, process-based desulfurization rates are low, reaching only around 50%, failing to meet ultra-low emissions requirements. While waste desulfurization technologies, such as XRD and activated carbon, offer high removal rates, they are subject to high operating costs and demanding reaction conditions, significantly increasing costs for the steel industry and severely hindering its development.

[0003] Patent document CN202310517325.6, a device for desulfurizing steel slag using a waste gas sintering method, discloses a device for desulfurizing steel slag using a waste gas sintering method. The device includes a slag crushing device and a desulfurization and dust removal device. The desulfurization and dust removal device includes a cavity shell having a flue gas duct and a mixing and stirring device installed in the flue gas duct. The flue gas duct wall is penetrated by a porous passive nozzle connected to and communicated with the discharge port of the mixing and stirring device. The process includes: the slag crushing device crushes the steel slag into slag powder and transports it to the slag crushing device to form a slag powder slurry. The flue gas duct is dispersed and inhaled by the porous passive nozzle through the high-speed sulfur-containing flue gas flowing through it. The high-speed flue gas flowing in the flue gas duct is used to attract the slag powder slurry into the flue gas duct, thereby achieving the purpose of energy saving. The flue gas carrying the slag powder slurry in the flue gas duct is further diffused when entering the cavity shell to facilitate the mixing of the flue gas and the slag powder slurry, thereby improving the desulfurization effect of the flue gas.

[0004] Patent document CN202322443421.9, titled "Device for Preparing Steel Slag Desulfurization Slurry," discloses a device for preparing steel slag desulfurization slurry. The device comprises a primary slurrying system, a slurry external circulation system, a spiral slag extractor, a waste bin, a slurry overflow pipe, and a secondary slurrying system. The primary slurrying system is used to prepare the steel slag desulfurization slurry, while the secondary slurrying system is used to supplement the prepared steel slag desulfurization slurry with calcium, which is essential for the desulfurization reaction. The device provided by this utility model ensures the stability and continuity of the overall desulfurization process system.

[0005] Patent document CN201610614300.8, "Steel Slag-Based Modified Desulfurizer for Wet Desulfurization, Preparation Method, and Application thereof," provides a steel slag-based modified desulfurizer for wet desulfurization and its preparation method. The steel slag-based modified desulfurizer for wet desulfurization comprises the following materials by weight: 92.0 to 99.0 parts of steel slag and 1.0 to 8.0 parts of phosphoric acid. The desulfurizer of the present invention not only transforms waste into valuables, but also achieves high desulfurization efficiency, is environmentally friendly, and improves energy efficiency.

[0006] Steel slag is the main waste product of the steel industry. Its main components are metal oxides. From the perspective of chemical composition, it can be used as a desulfurizer. From the perspective of existing technology, wet desulfurization is used when steel slag is used as a desulfurizer. That is, the steel slag is ground and formed into a slurry to increase the reaction rate between SO2 in the exhaust gas and the desulfurization components in the steel slag. However, sulfur-containing saturated steam and wastewater will appear during the desulfurization process, which will breed secondary harmful substances. At the same time, the cost of grinding steel slag is high, which is not conducive to reducing the cost of desulfurization. From the perspective of the chemical reaction formula, temperature plays a significant role in promoting the reaction intensity of metal oxides such as SO2 and CaO. The present invention uses the waste heat of the steel rolling heating furnace to provide a reasonable reaction temperature and reaction time, thereby achieving truly efficient dry desulfurization using steel slag as a desulfurizer. Summary of the Invention

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

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A dry desulfurization device for a steel rolling heating furnace using steel slag as a desulfurizer comprises 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 comprises a desulfurization device support frame, a desulfurizer receiving pipe, a seal, and a desulfurizer. A mounting 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 mounting hole. The desulfurizer is filled in the desulfurizer receiving pipe, and the desulfurizer receiving pipe is inserted into the desulfurization device support frame. The upper end of the desulfurizer receiving pipe is filled with a seal.

[0010] The desulfurizer is crushed steel slag with an oxide content greater than 50%, and the particle size of the steel slag is 2-25 mm.

[0011] The sealing element is a high temperature resistant fiber blanket or rock wool.

[0012] The desulfurization device is arranged in a multi-row and multi-column structure in the flue of the heating furnace, and the rows are staggered.

[0013] A hoisting device is provided at the upper end of the desulfurizer holding pipe.

[0014] The desulfurizing agent holding pipe and the desulfurization device support frame are both in the shape of a mesh, and the nominal diameter of the mesh is smaller than the minimum particle size of the desulfurizing agent.

[0015] The heat exchange air in the air heat exchanger is the combustion air of the heating furnace, and the heat exchange gas in the gas heat exchanger is the fuel gas of the heating furnace.

[0016] The equivalent diameter of the desulfurizing agent holding pipe is between 50 and 200 mm.

[0017] A method for using a dry desulfurization device in a steel rolling heating furnace using steel slag as a desulfurizer comprises:

[0018] 1) The temperature of high-temperature flue gas in the heating furnace flue shall not be lower than 750℃.

[0019] 2) The total amount of slag charged is calculated based on the exhaust volume of the heating furnace and the total amount of harmful components in the flue gas, while taking into account the service life of the desulfurization device. The calculation method is:

[0020]

[0021] Where: G 脱硫剂 : Total weight of desulfurizer during the service life, t / cycle;

[0022] Vy: average smoke exhaust volume during the service life, Nm 3 / h;

[0023] φ(SO2): Average SO2 content in flue gas, mg / Nm 3 ;

[0024] τ: usage cycle time, h;

[0025] φ (金属氧化物) : The proportion of metal oxides in steel slag, %.

[0026] 3) To ensure that SO2 in the flue gas reacts fully with the metal oxides in the steel slag, the equivalent diameter of the desulfurizer holding pipe should not be too large. A multi-row and multi-column structure should be adopted, with staggered arrangement between rows. The pipe spacing is the same as the diameter of the desulfurizer holding pipe. The number of pipes in each row is:

[0027]

[0028] In the formula: m: number of desulfurizer support tubes in each row, tubes / row;

[0029] W: inner width of flue, m;

[0030] D: Equivalent diameter of the desulfurizer holding pipe, m.

[0031] 4) The number of rows of desulfurizer holding pipes shall be calculated based on the total weight of desulfurizer in the service life (G) 脱硫剂 Divide by the load amount of each row. The specific calculation formula is as follows:

[0032]

[0033] Where: n: number of rows of desulfurizer support tubes;

[0034] ρ 渣 : Bulk density of steel slag as desulfurizer; kg / m 3 ;

[0035] H: Height inside the flue, m.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention proposes a dry desulfurization device and method for a steel rolling heating furnace using steel slag as a desulfurizer. The device utilizes the metal oxides in the steel slag to react with SO2 in the flue gas of the heating furnace at high temperature, thereby increasing the desulfurization rate by more than 50% while significantly reducing the desulfurization cost of the steel plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is an overall schematic diagram of the dry desulfurization device of the steel rolling heating furnace using steel slag as a desulfurizer.

[0039] Figure 2 It is a partial cross-sectional view of the desulfurization device.

[0040] Figure 3 This is a schematic diagram of the desulfurizer holding pipe.

[0041] In the figure: 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. Seal; 11. Lifting equipment; 12. Desulfurization agent receiving pipe. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the specific implementation methods of the present invention are further described below in conjunction with examples. The following examples are used to specifically illustrate the contents of the present invention. These examples are only general descriptions of the contents of the present invention and do not limit the contents of the present invention.

[0043] See Figure 1-Figure 3A dry desulfurization device for a steel rolling heating furnace using steel slag as a desulfurizer comprises 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 flue 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 flue gas heat exchanger 5. The desulfurization device 3 comprises a desulfurization device support frame 9, a desulfurizer receiving pipe 12, a seal 10, and a desulfurizer. A mounting 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 mounting hole 8. The desulfurizer is filled in the desulfurizer receiving pipe 12. The desulfurizer receiving pipe 12 is inserted into the desulfurization device support frame 9. The upper end of the desulfurizer receiving pipe 12 is filled with a seal 10.

[0044] The desulfurizer is crushed steel slag with an oxide content greater than 50%, and the particle size of the steel slag is 2 to 25 mm.

[0045] The sealing member 10 is a high temperature resistant fiber blanket or rock wool.

[0046] The desulfurization device 3 is arranged in a multi-row and multi-column structure in the flue 2 of the heating furnace, and the rows are staggered.

[0047] A hoisting device 11 is provided at the upper end of the desulfurizing agent receiving pipe 12 .

[0048] The desulfurizing agent holding pipe 12 and the desulfurization device support frame 9 are both in the shape of a mesh, and the nominal diameter of the mesh is smaller than the minimum particle size of the desulfurizing agent.

[0049] The heat exchange air in the air heat exchanger 4 is the combustion air for the furnace, and the heat exchange gas in the gas heat exchanger 5 is the fuel gas for the heating furnace.

[0050] The equivalent diameter of the desulfurizing agent holding pipe 12 is between 50 and 200 mm.

[0051] A method for using a dry desulfurization device in a steel rolling heating furnace using steel slag as a desulfurizer comprises:

[0052] 1) In order to ensure the desulfurization efficiency and desulfurization reaction time and reduce the generation of CaCO3, the high-temperature flue gas temperature in the heating furnace flue 2 is not less than 750℃.

[0053] 2) The total amount of slag charged is calculated based on the exhaust volume of the heating furnace and the total amount of harmful components in the flue gas, while taking into account the service life of the desulfurization device. The calculation method is:

[0054]

[0055] Where: G 脱硫剂 : Total weight of desulfurizer during the service life, t / cycle;

[0056] Vy: average smoke exhaust volume during the service life, Nm 3 / h;

[0057] φ(SO2): Average SO2 content in flue gas, mg / Nm 3 ;

[0058] τ: usage cycle time, h;

[0059] φ (金属氧化物) : The proportion of metal oxides in steel slag, %.

[0060] 3) To ensure that SO2 in the flue gas reacts fully with the metal oxides in the steel slag, the equivalent diameter of the desulfurizer holding pipe 12 should not be too large. A multi-row and multi-column structure is adopted, with staggered arrangement between rows. The pipe spacing is the same as the diameter of the desulfurizer holding pipe 12. The number of pipes in each row is:

[0061]

[0062] In the formula: m: number of desulfurizer support tubes in each row, tubes / row;

[0063] W: inner width of flue, m;

[0064] D: Equivalent diameter of the desulfurizer holding pipe, m.

[0065] 4) The number of rows of desulfurizer holding pipes shall be calculated based on the total weight of desulfurizer in the service life (G) 脱硫剂 Divide by the load amount of each row. The specific calculation formula is as follows:

[0066]

[0067] Where: n: number of rows of desulfurizer support tubes;

[0068] ρ 渣 : Bulk density of steel slag as desulfurizer; kg / m 3 ;

[0069] H: Height inside the flue, m.

[0070] See Figure 1The exhaust system of a conventional heating furnace does not have a desulfurization device 3. The high-temperature flue gas generated by combustion in the heating furnace enters the heating furnace flue 2 through the heating furnace flue inlet 1, and passes through the air heat exchanger 4 and the gas heat exchanger 5. The high-temperature flue gas and air gas are heat-exchanged to become low-temperature exhaust gas, which is then discharged from the heating furnace system through the chimney 6. The present invention adds n rows and m columns of desulfurization devices 3 between the heating furnace flue inlet 1 and the air heat exchanger 4, and uses the temperature of the high-temperature flue gas to catalyze the reaction between the metal oxides in the steel slag and the SO2 component in the flue gas. At the same time, the high temperature is used to suppress the reaction between CO2 in the flue gas and the metal oxides, thereby achieving dry and efficient desulfurization. The desulfurization device 3 is divided into two parts. The structure inside the furnace is shown in the attached figure. Figure 2 A hole is opened at the top of the refractory layer 7 of the flue 2 in front of the air heat exchanger 4 of the heating furnace flue. The hole shape can be circular, square, triangular or other shapes. A desulfurization device support frame 9 is set through the mounting hole 8 to support the desulfurization device. The support frame is made of high-temperature corrosion-resistant steel and can be in the shape of a mesh column or other shapes. The external structure of the desulfurization device is shown in the attached figure. Figure 3 The desulfurizer holding pipe 12 is plugged into the desulfurization device support frame 9. The desulfurizer holding pipe 12 is a mesh column structure. The cross-sectional shape is consistent with the mounting hole 8. The nominal diameter is 2 to 10 mm smaller than the mounting hole for easy installation. The bottom of the desulfurizer holding pipe 12 is in contact with the flue refractory layer 7. The height is 10 to 50 mm higher than the outside of the flue. The material is high-temperature corrosion-resistant steel or other metals or non-metals resistant to high-temperature oxidation. The mesh nominal diameter is smaller than the minimum particle size of the desulfurizer. A lifting device 11 is installed on the top of the desulfurizer holding pipe 12.

[0071] The desulfurizer of the present invention adopts waste steel slag after steelmaking production. After crushing, steel slag with a diameter of 5 to 25 mm is screened out as the desulfurizer, which is loaded into the desulfurizer receiving pipe 12. The loading height is the same as the inner height of the flue refractory layer 7. High-temperature resistant fiber blanket or rock wool is filled at the position of the seal 10 for sealing. The desulfurizer receiving pipe 12 filled with desulfurizer and high-temperature resistant fiber blanket or rock wool is loaded into the desulfurization device support frame 9 by using a lifting device 11, and the gap between the mounting hole 8 and the desulfurizer receiving pipe 12 is further sealed with a refractory and high-temperature resistant fiber blanket or rock wool. The metal oxides in the steel slag in the desulfurizer receiving pipe 12 are used to remove SO2 in the high-temperature flue gas, and stable CaSO4 is generated in the aerobic environment of the flue gas. At the same time, due to the high temperature environment, the removal rate is greatly improved while the generation of CaCO3 is effectively suppressed, thereby greatly improving the service life of the desulfurizer.

[0072] The desulfurizer can be converter slag, refined slag or other steel slag waste with metal oxides greater than 50%.

[0073] Example 1:

[0074] A wire rod heating furnace in a factory uses 2000Kcal / Nm 3 Mixed gas is used as fuel, gas volume is 20000Nm3 / h, normal production exhaust volume 62500Nm 3 / h, the flue is 6.7m wide and 3m high, and the current flue gas SO2 content is 100mg / Nm 3 , meeting the current environmental protection standards, but not meeting the ultra-low emission standards. According to this method, converter slag is used as a desulfurizer, and the bulk density of the slag is 2100kg / m 3 The metal oxide content of steel slag is 70%. The desulfurizer service life is designed based on a 3-month operation time (2100h). To achieve ultra-low emissions, 5.28t of SO2 needs to be removed, and 5.70t of desulfurizer is required. A 100mm diameter round tube is used as the support frame for the desulfurization device. 136 desulfurization support tubes need to be arranged, with 34 tubes in each row in 4 rows along the horizontal flue, in staggered arrangement. When the flue gas temperature is stable at around 800℃, the flue gas emission SO2 content of 48mg / Nm 3 The desulfurization rate is increased by more than 52%, meeting the national ultra-low emission standards. At the same time, the performance of the treated steel slag is stable, the content of free calcium oxide and magnesium oxide is greatly reduced, and further resource utilization is quickly achieved.

[0075] Example 2:

[0076] A plate heating furnace in a certain factory uses 4000Kcal / Nm 3 Mixed gas is used as fuel, gas volume is 18000Nm 3 / h, normal production exhaust volume 98500Nm 3 / h, the flue is 13m wide and 3m high, and the current flue gas SO2 content is 80mg / Nm 3 , also meets the current environmental protection standards, but does not meet the ultra-low emission standards. According to this method, the metal oxide content of steel slag is 80%, and the bulk density is 1900kg / m 3 The desulfurization agent service life is designed based on a 4-month operation time (2800h). To achieve ultra-low emissions, 10.58t of SO2 needs to be removed, and 11.58t of desulfurization agent is required. 100mm diameter round tubes are used as support tubes. 260 desulfurization support tubes need to be arranged, and 4 rows of 65 tubes are arranged along the horizontal flue in staggered rows. When the flue gas temperature is stable at around 850℃, the flue gas emission SO2 content can reach 32mg / Nm 3 The desulfurization rate is increased by more than 68%, meeting the national ultra-low emission standards. At the same time, the performance of the treated steel slag is stable, the content of free calcium oxide and magnesium oxide is greatly reduced, and further resource utilization is quickly achieved.

Claims

1. A dry desulfurization device for a steel rolling heating furnace using steel slag as a desulfurizer, 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 arranged in 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 desulfurizer receiving pipe, a seal, and a desulfurizer. A mounting 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 mounting hole. The desulfurizer is filled in the desulfurizer receiving pipe. The desulfurizer receiving pipe is inserted into the desulfurization device support frame. The upper end of the desulfurizer receiving pipe is filled with a seal.

2. The dry desulfurization device for a steel rolling heating furnace using steel slag as a desulfurizer according to claim 1, characterized in that: The desulfurizer is crushed steel slag with an oxide content greater than 50%, and the particle size of the steel slag is 2 to 25 mm.

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

4. The dry desulfurization device for a steel rolling heating furnace using steel slag as a desulfurizer according to claim 1, characterized in that: The desulfurization device is arranged in a multi-row and multi-column structure in the flue of the heating furnace, and the rows are staggered.

5. The dry desulfurization device for a steel rolling heating furnace using steel slag as a desulfurizer according to claim 1, characterized in that: A hoisting device is provided at the upper end of the desulfurizer holding pipe.

6. The dry desulfurization device for a steel rolling heating furnace using steel slag as a desulfurizer according to claim 1, characterized in that: The desulfurizing agent holding pipe and the desulfurization device support frame are both in the shape of a mesh, and the nominal diameter of the mesh is smaller than the minimum particle size of the desulfurizing agent.

7. The dry desulfurization device for a steel rolling heating furnace using steel slag as a desulfurizer according to claim 1, characterized in that: The heat exchange air in the air heat exchanger is the combustion-supporting air for the furnace, and the heat exchange gas in the gas heat exchanger is the fuel gas for the heating furnace.

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

9. A method for using the steel slag as a desulfurizing agent in a dry desulfurization device for a steel rolling heating furnace according to any one of claims 1 to 8, characterized in that: include: 1) The temperature of high-temperature flue gas in the heating furnace flue is not less than 750℃; 2) The total amount of slag charged is calculated based on the exhaust volume of the heating furnace and the total amount of harmful components in the flue gas, while taking into account the service life of the desulfurization device. The calculation method is: Where: G 脱硫剂 : Total weight of desulfurizer during the service life, t / cycle; Vy: average smoke exhaust volume during the service life, Nm 3 / h; φ(SO2): Average SO2 content in flue gas, mg / Nm 3 ; τ: usage cycle time, h; φ (金属氧化物) : The proportion of metal oxides in steel slag, %; 3) The spacing between the desulfurizer holding pipes is the same as the diameter of the desulfurizer holding pipes. The number of pipes in each row is: In the formula: m: number of desulfurizer support tubes in each row, tubes / row; W: inner width of flue, m; D: equivalent diameter of desulfurizer holding pipe, m; 4) The number of rows of desulfurizer holding pipes shall be calculated based on the total weight of desulfurizer in the service life (G) 脱硫剂 Divide by the load amount of each row. The specific calculation formula is as follows: Where: n: number of rows of desulfurizer support tubes; ρ 渣 : Bulk density of steel slag as desulfurizer; kg / m 3 ; H: Height inside the flue, m.

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