Method and device for recovering waste heat from converter primary flue gas injection quenching

Abstract

The present invention relates to the technical field of waste heat recovery facilities for steelmaking converters in steel enterprises, and specifically to a method and device for recovering waste heat from converter primary flue gas induced quenching, comprising a radiation waste heat boiler, a convection waste heat boiler, a gas pipeline, and a dry quenching chamber for extinguishing open flames in flue gas and reducing the energy of fire particles in flue gas; a vaporization cooling flue, the radiation waste heat boiler, the dry quenching chamber, the convection waste heat boiler and the gas pipeline are sequentially connected along the flue gas flow direction, a quenching gas inlet is provided on the dry quenching chamber, the quenching gas inlet is connected to the gas pipeline through a quenching gas bypass pipe, and an inert gas induced device is provided on the quenching gas bypass pipe. The present invention fully recovers the waste heat of 900℃ to 250℃ of converter primary flue gas, can realize full dry waste heat recovery and purification, and avoids the risk of flash explosion of converter gas in the range of 605~650℃, significantly improving the safety of the system.

Description

Technical Field

[0001] The invention relates to the technical field of waste heat recovery facilities for steelmaking converters in steel enterprises, and in particular to a method and device for recovering waste heat from primary flue gas-injection quenching of converters. Background Art

[0002] During converter smelting, the primary flue gas temperature at the outlet of the vaporization flue of a conventional converter is 900℃~1000℃, and then enters the wet dust removal or dry dust removal system. Usually, water spray is used to cool the temperature down to about 200℃ before purification and recovery. In this process, the flue gas waste heat of 900℃~200℃ is not recycled and is wasted. The main reason why this part of waste heat is not recycled is that there is a risk of explosion of converter gas in the medium and low temperature sections. From the thermodynamics of combustible gases, it can be seen that the following three conditions must be met at the same time for gas explosion:

[0003] 1) The mixture ratio of carbon monoxide and oxygen or air is within the explosion limit;

[0004] 2) Carbon monoxide is premixed with oxygen or air below the autoignition point (605-650°C);

[0005] 3) Encountering an open flame or a fire with sufficient energy.

[0006] Therefore, in order to ensure the recovery and utilization of this part of heat under the premise of safety, it is necessary to ensure that the above three conditions cannot be met at the same time. Summary of the invention

[0007] The purpose of the present invention is to provide a converter primary flue gas injection quenching waste heat recovery device, which can fully recover the 900℃~250℃ waste heat of the converter primary flue gas under the premise of ensuring safety, eliminate water spraying in the flue gas purification process, and realize high-safety, fully dry waste heat recovery.

[0008] To achieve the above-mentioned purpose, the technical solution of the present invention is a converter primary flue gas injection quenching waste heat recovery device, comprising a radiation waste heat boiler, a convection waste heat boiler, a gas pipeline and a dry quenching chamber for extinguishing open flames in the flue gas and reducing the energy of fire particles in the flue gas; the vaporization cooling flue, the radiation waste heat boiler, the dry quenching chamber, the convection waste heat boiler and the gas pipeline are connected in sequence along the flue gas flow direction, and a quenching gas inlet is provided on the dry quenching chamber, and the quenching gas inlet is connected to the gas pipeline through a quenching gas bypass pipe, and an inert gas injection device is provided on the quenching gas bypass pipe.

[0009] As one of the embodiments, the inert gas injection device includes a venturi, an inert gas injection nozzle and an inert gas pipeline. The venturi is arranged in the quenching gas bypass pipe, the port of the venturi tapered section faces the gas pipeline and is provided with an inert gas injection nozzle, and the inert gas injection nozzle is connected to the inert gas pipeline.

[0010] As one of the implementation modes, a gas non-return device is further provided in the quenching gas bypass pipe, and the gas non-return device is located between the quenching gas inlet and the inert gas ejection device.

[0011] As one of the embodiments, the dry quenching chamber includes an air inlet section and a mixed air cooling section arranged in sequence from top to bottom, the top of the air inlet section is connected to the radiation waste heat boiler, the bottom of the mixed air cooling section is connected to the convection waste heat boiler, and the quenching gas inlet is arranged on the air inlet section.

[0012] As one of the implementation modes, the air inlet section is a double-layer structure consisting of an inner wall and an outer wall, the outer wall is provided with the quenching gas inlet, the inner wall is provided with an air supply port, and the bottom of the inner wall is connected to the top of the mixed air cooling section.

[0013] As one of the implementation modes, an explosion relief valve is installed on the side wall of the mixed air cooling section.

[0014] As one of the implementation modes, the radiation waste heat boiler is connected to the dry quenching chamber through a compensator.

[0015] The present invention also provides a method for recovering waste heat from primary flue gas injection quenching of a converter, using any one of the above-mentioned waste heat recovery devices for primary flue gas injection quenching of a converter, the method comprising the following steps:

[0016] 1) During converter smelting, the flue gas with a temperature of 900-1000℃ at the outlet of the vaporization cooling flue enters the radiation waste heat boiler for waste heat recovery, and the flue gas temperature is reduced to 660-700℃ through radiation heat exchange;

[0017] 2) The flue gas with a temperature of 660-700℃ at the outlet of the radiation waste heat boiler enters the dry quenching chamber and is mixed and quenched with part of the flue gas from the outlet of the convection waste heat boiler. The flue gas temperature is quenched to 500℃~550℃, extinguishing the open flame in the flue gas and reducing the energy of the fire particles in the flue gas;

[0018] 3) The flue gas with a temperature of 500℃~550℃ at the outlet of the dry quenching chamber enters the convection waste heat boiler for waste heat recovery, and the flue gas temperature is reduced to 250℃ through convection heat exchange;

[0019] 4) Part of the flue gas with a temperature of 250°C at the outlet of the convection waste heat boiler enters the quenching gas bypass pipe and is introduced into the dry quenching chamber as quenching gas through the inert gas injection device as quenching gas bypass power, and the other part is transported to the subsequent device through the gas pipeline for gas purification and recovery.

[0020] As one of the implementation methods, in step 4), the inert gas injection device introduces the inert gas through the inert gas pipeline into the inert gas injection nozzle at the port of the venturi tapered section for injection, driving part of the flue gas flowing out of the waste heat boiler outlet into the venturi and then into the dry quenching chamber.

[0021] As one of the implementation modes, the gas supply pressure of the inert gas pipeline is ≥1.0 MPa, and the flow rate of the quenching gas is adjusted by adjusting the gas supply pressure of the inert gas pipeline.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention fully recovers the waste heat of 900°C to 250°C of the converter primary flue gas during converter smelting, can achieve high-safety, fully dry waste heat recovery, and effectively reduce the production cost of steel products;

[0024] (2) The present invention effectively extinguishes open flames and reduces the energy of fire particles through a dry quenching chamber, thereby avoiding the risk of flash explosion of converter gas in the range of 605-650°C, achieving safe recovery of converter gas waste heat, and the dry quenching chamber is provided with an explosion relief valve, further ensuring the safety of the equipment;

[0025] (3) The quenching gas used in the present invention is drawn from the flue gas at the outlet of the convection waste heat boiler, which consumes less energy;

[0026] (4) The gas supply pressure of the inert gas ejection device of the present invention is ≥1.0 MPa, and the flow rate of the bypass quenching gas can be adjusted by adjusting the pressure;

[0027] (5) The present invention uses inert gas as the ejection power, which not only reduces energy consumption but also reduces the risk of flash explosion of converter gas in the range of 605-650°C;

[0028] (6) The inert gas ejection device of the present invention has no mechanical moving parts, thereby improving the reliability and service life of the system;

[0029] (7) The present invention provides a gas check device on the quenching gas bypass pipe to prevent the gas from flowing back. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A schematic diagram of a converter primary flue gas injection quenching waste heat recovery device provided in an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of the structure of a dry quenching chamber provided in an embodiment of the present invention;

[0033] Figure 3 for Figure 2 AA section view;

[0034] Figure 4 A schematic diagram of the structure of an inert gas ejection device provided in an embodiment of the present invention;

[0035] In the figure: 1. Vaporization cooling flue; 2. Radiant waste heat boiler; 3. Compensator; 4. Dry quenching chamber; 4-1. Air inlet section; 4-1a. Outer wall; 4-1b. Inner wall; 4-1c. Air supply port; 4-2. Mixed air cooling section; 4-3. Explosion relief valve; 5. Inertial dust removal device; 6. Convection waste heat boiler; 7. Inert gas injection device; 7-1. Venturi tube; 7-2. Inert gas injection nozzle; 7-3. Inert gas pipeline; 7-4. Fixed bracket; 7-5. Cylinder; 8. Quenching gas bypass pipe; 9. Gas check device; 10. Gas pipeline. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0038] Embodiment 1

[0039] like Figure 1 As shown, this embodiment provides a converter primary flue gas injection quenching waste heat recovery device, including a radiation waste heat boiler 2, a convection waste heat boiler 6, a gas pipeline 10 and a dry quenching chamber 4 for extinguishing open flames in the flue gas and reducing the energy of fire particles in the flue gas; the vaporization cooling flue 1, the radiation waste heat boiler 2, the dry quenching chamber 4, the convection waste heat boiler 6 and the gas pipeline 10 are connected in sequence along the flue gas flow direction, and a quenching gas inlet is provided on the dry quenching chamber 4, and the quenching gas inlet is connected to the gas pipeline 10 through a quenching gas bypass pipe 8, and an inert gas injection device 7 is provided on the quenching gas bypass pipe 8.

[0040] In this embodiment, the flue gas at the outlet of the convection waste heat boiler 6 is introduced into the dry quenching chamber 4 as a quenching gas, and the flue gas at the outlet of the radiation waste heat boiler 2 is quenched and cooled, which consumes less energy, extinguishes the flue gas in the flue gas and reduces the energy of the fire particles in the flue gas, thereby avoiding the risk of flash explosion of the converter gas in the range of 605~650℃, effectively improving the safety of the converter gas waste heat recovery, and at the same time, the radiation waste heat boiler 2 and the convection waste heat boiler 6 fully recover the 900℃~250℃ waste heat of the converter primary flue gas, realizing high-safety, full-dry waste heat recovery and purification, and reducing the production cost of steel products.

[0041] The above embodiment is refined, such as Figure 4 As shown, the inert gas injection device 7 includes a venturi 7-1, an inert gas injection nozzle 7-2 and an inert gas pipeline 7-3, wherein the venturi 7-1 is arranged in the quenching gas bypass pipe 8, the port of the tapered section of the venturi 7-1 faces the gas pipeline 10 and is provided with an inert gas injection nozzle 7-2, and the inert gas injection nozzle 7-2 is connected to one end of the inert gas pipeline 7-3. The inert gas injection device 7 of this embodiment uses inert gas as bypass power, which can further reduce the risk of flash explosion of converter gas in the range of 605-650°C, improve the safety of the system, and at the same time, the inert gas injection device 7 has no mechanical moving parts, which improves the reliability and service life of the system.

[0042] Specifically, the venturi tube 7-1 includes a tapered section, a throat section and a gradually expanding section connected in sequence, the port of the tapered section of the venturi tube 7-1 faces the gas pipeline 10 and is provided with an inert gas injection nozzle 7-2, and the port of the gradually expanding section of the venturi tube 7-1 faces the quenching gas inlet. One end of the inert gas pipeline 7-3 is connected to the inert gas injection nozzle 7-2, and the other end of the inert gas pipeline 7-3 extends to the outside of the quenching gas bypass pipe 8 and is connected to the inert gas source through a valve. Specifically, the inert gas can be nitrogen or the like.

[0043] In this embodiment, the venturi tube 7-1 can be directly arranged in the quenching gas bypass pipe 8, and the outer edges of the tapered section port and the expanded section port of the venturi tube 7-1 are respectively sealed and connected to the inner wall 4-1b of the quenching gas bypass pipe 8. Alternatively, the venturi tube 7-1 can be arranged in the cylinder 7-5, the quenching gas bypass pipe 8 is disconnected at the venturi tube 7-1, and the two ends of the cylinder 7-5 are respectively sealed and connected to the disconnected parts of the quenching gas bypass pipe 8 on both sides. Furthermore, the inert gas pipeline 7-3 is extended into the quenching gas bypass pipe 8 and then bent and connected to the inert gas injection nozzle 7-2. The bent position of the inert gas pipeline 7-3 is fixed in the quenching gas bypass pipe 8 by a fixing bracket 7-4.

[0044] Optimally, a gas check device 9 is further provided in the quenching gas bypass pipe 8, and the gas check device 9 is located between the quenching gas inlet and the inert gas ejection device 7. By adding the gas check device 9 in the cold gas bypass pipe, the gas backflow can be prevented.

[0045] like Figure 2 and Figure 3 As shown, the dry quenching chamber 4 includes an air inlet section 4-1 and a mixed air cooling section 4-2 arranged in sequence from top to bottom, the top of the air inlet section 4-1 is connected to the radiation waste heat boiler 2, the bottom of the mixed air cooling section 4-2 is connected to the convection waste heat boiler 6, and the quenching gas inlet is arranged on the air inlet section 4-1. Further, the air inlet section 4-1 is a double-layer structure composed of an inner wall 4-1b and an outer wall 4-1a, the quenching gas inlet is arranged on the outer wall 4-1a, the air outlet 4-1c is arranged on the inner wall 4-1b, and the bottom of the inner wall 4-1b is connected to the top of the mixed air cooling section 4-2. Among them, the cavity surrounded by the inner wall 4-1b is connected with the cavity of the mixed air cooling section 4-2, the outer wall 4-1a is sleeved outside the inner wall 4-1b, and the upper and lower ends are sealed. The space between the inner wall 4-1b and the outer wall 4-1a serves as an air supply channel. The quenching gas enters the quenching gas inlet through the quenching gas inlet, and then enters the cavity of the inner wall 4-1b through the air supply port 4-1c to mix with the high-temperature flue gas from the radiation waste heat boiler 2 and enters the mixed air cooling section 4-2 for quenching, thereby extinguishing the open flame in the flue gas, reducing the energy of the fire particles in the flue gas, and avoiding the risk of flash explosion of the converter gas in the range of 605~650℃.

[0046] Furthermore, there are several air supply ports 4-1c, and the several air supply ports 4-1c are arranged at equal intervals along the circumferential direction of the inner wall 4-1b, so that the quenching gas and the high-temperature flue gas from the radiation waste heat boiler 2 are quickly mixed and evenly cooled, thereby avoiding the occurrence of open flames and the escape of fire.

[0047] Optimally, such as Figure 2As shown, an explosion relief valve 4-3 is installed on the side wall of the mixed air cooling section 4-2. Multiple explosion relief valves 4-3 can be set. When the pressure of the mixed air cooling section 4-2 exceeds the set value, the explosion relief valve 4-3 opens to release the pressure, further ensuring the safety of the equipment.

[0048] like Figure 1 As shown, the radiation waste heat boiler 2 is connected to the dry quenching chamber 4 through a compensator 3 to absorb the thermal displacement of the equipment and avoid damage to the equipment.

[0049] As one of the implementation modes, the flue gas outlet of the dry quenching chamber 4 is connected to the flue gas inlet of the inertial dust removal device 5, and the flue gas outlet of the inertial dust removal device 5 is connected to the flue gas inlet of the convection waste heat boiler 6. The inertial dust removal device 5 can remove coarse dust in the flue gas and reduce scaling and scouring of the convection waste heat boiler 6.

[0050] Embodiment 2

[0051] like Figure 1-Figure 4 As shown, this embodiment provides a method for recovering waste heat from converter primary flue gas injection quenching, using the converter primary flue gas injection quenching waste heat recovery device provided in Example 1, and the method includes the following steps:

[0052] 1) During converter smelting, the flue gas with a temperature of 900-1000°C at the outlet of the vaporization cooling flue 1 enters the radiation waste heat boiler 2 for waste heat recovery, and the flue gas temperature is reduced to 660-700°C through radiation heat exchange;

[0053] 2) The flue gas with a temperature of 660-700°C at the outlet of the radiation waste heat boiler 2 enters the dry quenching chamber 4 and is mixed with part of the flue gas (temperature of 250°C) from the outlet of the convection waste heat boiler 6 for quenching. The flue gas temperature is quenched to 500-550°C. The dry quenching chamber 4 effectively extinguishes the open flame in the flue gas and reduces the energy of the fire particles in the flue gas, avoiding the risk of flash explosion of converter gas in the range of 605-650°C. At the same time, the dry quenching chamber 4 is provided with an explosion relief valve 4-3 to ensure the safety of the equipment.

[0054] 3) The flue gas with a temperature of 500°C to 550°C at the outlet of the dry quenching chamber 4 enters the convection waste heat boiler 6 for waste heat recovery, and the flue gas temperature is reduced to 250°C through convection heat exchange;

[0055] 4) A portion of the flue gas at the outlet of the convection waste heat boiler 6 with a temperature of 250°C enters the quenching gas bypass pipe 8 and is introduced into the dry quenching chamber 4 as quenching gas through the inert gas injection device 7 as a quenching gas bypass power, and the other portion is transported to the subsequent device through the gas pipeline 10 for gas purification and recovery.

[0056] In step 4), the inert gas injection device 7 introduces the inert gas through the inert gas pipeline 7-3 into the inert gas injection nozzle 7-2 at the port of the tapered section of the venturi 7-1 for injection, driving part of the flue gas at the outlet of the waste heat boiler to enter the venturi 7-1, and then enter the dry quenching chamber 4. The quenching gas is drawn from the flue gas at the outlet of the convection waste heat boiler 6 nearby, which can reduce energy consumption. Furthermore, the gas supply pressure of the inert gas pipeline 7-3 is ≥1.0MPa, and the flow rate of the quenching gas can be adjusted by adjusting the gas supply pressure of the inert gas pipeline 7-3, thereby controlling the flue gas temperature at the outlet of the dry quenching chamber 4. The use of inert gas as the injection power further reduces the risk of flash explosion of converter gas in the range of 605~650℃, and improves the safety of the system. Specifically, the inert gas can be nitrogen or the like.

[0057] Optimally, in step 3), the flue gas at the outlet of the dry quenching chamber 4 with a temperature of 500°C to 550°C first enters the inertial dust removal device 5 to remove coarse dust, and then enters the convection waste heat boiler 6 for waste heat recovery. The inertial dust removal device 5 removes part of the flue dust, thereby reducing the scaling and scouring of the convection waste heat boiler 6.

[0058] The above embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the contents of the present invention, those skilled in the art can make various changes or modifications to the present invention, for example, adjusting the gas source pressure of the inert gas ejection device 7, using other inert gases as ejection power, adjusting the inlet and outlet flue gas temperatures of the radiation waste heat boiler 2, adjusting the inlet and outlet flue gas temperatures of the convection waste heat boiler 6, adjusting the position of the quenching gas bypass pipe 8, adjusting the number and arrangement of the air supply ports 4-1c, and these equivalent forms also fall within the scope defined by the claims attached to the present invention.

Claims

1. A converter primary flue gas injection type quenching waste heat recovery device, characterized in that: It includes a radiation waste heat boiler, a convection waste heat boiler, a gas pipeline and a dry quenching chamber for extinguishing open flames in the flue gas and reducing the energy of fire particles in the flue gas; the vaporization cooling flue, the radiation waste heat boiler, the dry quenching chamber, the convection waste heat boiler and the gas pipeline are connected in sequence along the flue gas flow direction, and the dry quenching chamber is provided with a quenching gas inlet, which is connected to the gas pipeline through a quenching gas bypass pipe, and the quenching gas bypass pipe is provided with an inert gas induced device; the dry quenching chamber includes a quenching gas inlet connected to the gas pipeline through a quenching gas bypass pipe, and an inert gas induced device is provided on the quenching gas bypass pipe ... An air inlet section and a mixed air cooling section are arranged in sequence from bottom to top, the top of the air inlet section is connected to the radiation waste heat boiler, the bottom of the mixed air cooling section is connected to the convection waste heat boiler, and the quenching gas inlet is arranged on the air inlet section; the air inlet section is a double-layer structure consisting of an inner wall and an outer wall, the quenching gas inlet is arranged on the outer wall, and an air supply port is arranged on the inner wall, and the bottom of the inner wall is connected to the top of the mixed air cooling section; there are a plurality of air supply ports, and the plurality of air supply ports are arranged equidistantly along the circumferential direction of the inner wall.

2. The converter primary flue gas injection type quenching waste heat recovery device according to claim 1, characterized in that: The inert gas injection device includes a venturi, an inert gas injection nozzle and an inert gas pipeline. The venturi is arranged in the quenching gas bypass pipe. The port of the venturi tapered section faces the gas pipeline and is provided with an inert gas injection nozzle. The inert gas injection nozzle is connected to the inert gas pipeline.

3. The converter primary flue gas injection type quenching waste heat recovery device according to claim 2, characterized in that: A gas check device is also provided in the quenching gas bypass pipe, and the gas check device is located between the quenching gas inlet and the inert gas ejection device.

4. The converter primary flue gas injection type quenching waste heat recovery device according to claim 1, characterized in that: An explosion relief valve is installed on the side wall of the mixed air cooling section.

5. The converter primary flue gas injection type quenching waste heat recovery device according to claim 1, characterized in that: The radiation waste heat boiler is connected to the dry quenching chamber through a compensator.

6. A method for recovering waste heat from converter primary flue gas injection quenching, characterized in that: The converter primary flue gas injection quenching waste heat recovery device according to claim 2 is adopted, and the method comprises the following steps: 1) During converter smelting, the flue gas with a temperature of 900-1000℃ at the outlet of the vaporization cooling flue enters the radiation waste heat boiler for waste heat recovery, and the flue gas temperature is reduced to 660-700℃ through radiation heat exchange; 2) The flue gas with a temperature of 660-700℃ at the outlet of the radiation waste heat boiler enters the dry quenching chamber and is mixed and quenched with part of the flue gas from the outlet of the convection waste heat boiler. The flue gas temperature is quenched to 500℃~550℃, extinguishing the open flame in the flue gas and reducing the energy of the fire particles in the flue gas; 3) The flue gas with a temperature of 500℃~550℃ at the outlet of the dry quenching chamber enters the convection waste heat boiler for waste heat recovery, and the flue gas temperature is reduced to 250℃ through convection heat exchange; 4) Part of the flue gas with a temperature of 250°C at the outlet of the convection waste heat boiler enters the quenching gas bypass pipe and is introduced into the dry quenching chamber as quenching gas through the inert gas injection device as quenching gas bypass power, and the other part is transported to the subsequent device through the gas pipeline for gas purification and recovery.

7. The method for recovering waste heat from converter primary flue gas injection quenching as claimed in claim 6, characterized in that: In step 4), the inert gas injection device introduces the inert gas into the inert gas injection nozzle at the port of the venturi tapered section through the inert gas pipeline for injection, driving part of the flue gas at the outlet of the convection waste heat boiler into the venturi and then into the dry quenching chamber.

8. The method for recovering waste heat from converter primary flue gas injection quenching as claimed in claim 7, characterized in that: The gas supply pressure of the inert gas pipeline is ≥1.0MPa, and the flow rate of the quenching gas is adjusted by adjusting the gas supply pressure of the inert gas pipeline.

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