A zero-emission synergistic waste heat utilization system and method for sintering ring cooler exhaust gas

Abstract

This invention discloses a zero-emission synergistic waste heat utilization system and method for sintering ring cooler exhaust gas. The exhaust gas outlets of sections I and II of the ring cooler are connected to the exhaust gas inlet of a waste heat boiler; the exhaust gas outlet of the waste heat boiler is connected to the air inlet of a first circulating fan, and the air outlet of the first circulating fan is divided into two paths, respectively connected to the section I and section II air boxes of the ring cooler, forming a flue gas circulation between sections I and II of the ring cooler; the air inlet of the first cooling fan is connected to the outdoor environment; the air outlet of the first cooling fan is connected to the section V air box of the ring cooler; the exhaust gas outlet of section V of the ring cooler is sequentially connected to the second circulating fan and the section IV air box of the ring cooler; the exhaust gas outlet of section IV of the ring cooler is sequentially connected to the third circulating fan and the section III air box of the ring cooler; the exhaust gas outlet of section III of the ring cooler is connected to the hot air hood of the sintering machine. This invention achieves efficient utilization of high-grade thermal energy.

Description

Technical Field

[0001] This invention relates to a zero-emission synergistic waste heat utilization system and method for sintering ring cooler exhaust gas. Background Art

[0002] In recent years, with increasingly stringent environmental protection requirements, steel companies have vigorously implemented technological upgrades to meet ultra-low emission standards for air pollutants. Among these upgrades, the annular cooler, a process in sintering and smelting, has historically generated significant amounts of dust-laden waste gas, especially in the medium- and low-temperature stages. Due to the lower waste heat grade and lower recovery value compared to the high-temperature stages, most steel companies have not recycled this waste gas. The medium- and low-temperature stages typically use annular cooling fans to draw in cold air from the environment to cool the ore, with the resulting waste gas directly emitted through chimneys. Under the current and increasingly stringent environmental regulations, this method will be gradually phased out, necessitating corresponding process improvements to comply with environmental requirements.

[0003] Currently, zero-emission technology for annular cooler exhaust gas has been piloted in a certain region, attracting close attention from industry professionals. It is expected to be gradually rolled out to more provinces in the future. Annular cooler exhaust gas contains a significant amount of dust particles and carries a large amount of waste heat. How to balance waste heat recovery and pollutant control to achieve both economic and environmental benefits is a technical issue of particular concern to steel companies. Summary of the Invention

[0004] To address the above problems, this invention provides a zero-emission synergistic waste heat utilization system for sintering ring cooler exhaust gas.

[0005] To achieve the above objectives, the waste heat utilization system of the sintering ring cooler with zero waste gas emission of the present invention includes at least a ring cooler, a waste heat boiler, a first circulating fan, a first cooling fan, a second circulating fan, and a third circulating fan.

[0006] The annular cooler is divided into sections I, II, III, IV, and V according to the temperature of the sintered ore from high to low. The exhaust gas outlets of sections I and II of the annular cooler are connected to the exhaust gas inlet of the waste heat boiler. The exhaust gas outlet of the waste heat boiler is connected to the air inlet of the first circulating fan. The air outlet of the first circulating fan is divided into two paths, which are respectively connected to the air box of section I and the air box of section II of the annular cooler, forming a flue gas circulation of sections I and II of the annular cooler.

[0007] The air inlet of the first cooling fan is connected to the outdoor environment, drawing in natural air from the atmosphere; the air outlet of the first cooling fan is connected to the V-section air box of the annular cooler; the V-section exhaust gas outlet of the annular cooler is connected in sequence to the second circulating fan and the IV-section air box of the annular cooler; the IV-section exhaust gas outlet of the annular cooler is connected in sequence to the third circulating fan and the III-section air box of the annular cooler; and the III-section exhaust gas outlet of the annular cooler is connected to the hot air hood of the sintering machine.

[0008] Furthermore, a multi-tube dust collector and an induced draft fan are sequentially installed along the exhaust gas flow path on the pipeline of the III-stage exhaust gas outlet of the annular cooler.

[0009] Furthermore, the exhaust gas outlet pipe of the second stage of the annular cooler is connected to the inlet of the induced draft fan via a deflector pipe.

[0010] Furthermore, the deflector pipe is equipped with a deflector valve for adjusting the amount of medium-temperature air drawn in from the exhaust gas of the second stage of the annular cooler.

[0011] Furthermore, a supplementary cooling air duct is provided on the air inlet duct of the first circulating fan. One end of the supplementary cooling air duct is connected to the outdoor environment, and the other end is connected to the air inlet duct of the first circulating fan. A cooling air valve is provided on the supplementary cooling air duct to supplement the air volume loss during the first and second stage exhaust gas circulation process of the circulating cooler.

[0012] Furthermore, the cold air valve and the deflector valve are adjustable.

[0013] Furthermore, the first circulating fan, the first cooling fan, the second circulating fan, and the third circulating fan are all equipped with frequency converters.

[0014] Furthermore, the waste heat boiler is a dual-pressure, dual-channel steam waste heat boiler, with the high-temperature air inlet channel and the medium-temperature air inlet channel respectively connected to the first-stage exhaust gas outlet and the second-stage exhaust gas outlet of the annular cooler; the waste heat boiler generates high-pressure and low-pressure steam, which is used to drive the steam turbine to generate electricity or to drive the sintering main exhaust fan.

[0015] To achieve the above objectives, the present invention provides a method for zero-emission combined with efficient waste heat utilization of sintering ring cooler exhaust gas, comprising the following steps:

[0016] The high-quality waste heat from sections I and II of the annular cooler is recovered and utilized through waste heat boiler 2, and the first circulating fan 3 provides the power for the flue gas circulation of sections I and II of the annular cooler.

[0017] The relatively low-quality waste heat from sections III, IV, and V of the annular cooler is connected in series to achieve cascaded temperature increase, generating medium-temperature hot air at the outlet of section III that can be used for hot air sintering; the first cooling fan 6, the second circulating fan 7, and the third circulating fan 8 sequentially provide the exhaust gas flow head for each section.

[0018] Furthermore, it also includes the following steps:

[0019] In cold weather or when the ore inlet temperature of the annular cooler is low, the first cooling fan, the second circulating fan, and the third circulating fan operate with reduced air volume. At the same time, the deflector valves are opened, and the medium-temperature hot exhaust gas from the outlet of the second stage of the annular cooler mixes with the exhaust gas from the third stage of the annular cooler to compensate for the reduced exhaust gas flow at the outlet of the third stage of the annular cooler and the possible problem of low air temperature, so as to avoid the adverse effects of changes in the operating conditions of this system on the production of the sintering machine.

[0020] This invention is based on the concept of zero-emission exhaust gas from the annular cooler. It fully utilizes the segmented waste heat characteristics of the annular cooler to recover the high and medium temperature waste heat from the annular cooler through a waste heat boiler, generating steam that can be used to drive a steam turbine to generate electricity or perform work, thus achieving efficient utilization of high-grade thermal energy. The medium and low temperature waste heat from the annular cooler is heated in cascade to generate higher temperature medium-temperature hot air for hot air sintering, thus achieving efficient utilization of medium and low temperature waste heat.

[0021] Based on the temperature characteristics of sinter, this invention adopts a stepped cooling method. The sinter in the high-temperature section is cooled by air at a higher temperature, while the sinter in the low-temperature section is cooled by air at a lower temperature. This can reduce the breakage rate of sinter during the cooling process and improve the yield of sinter.

[0022] This invention incorporates a multi-tube dust collector and an induced draft fan to purify and pressurize the exhaust gas used for hot air sintering. Compared to the unpowered conveying method of directly introducing exhaust gas into the hot air hood of the sintering machine, this increases the induced draft power and enhances the implementation effect of hot air sintering. The multi-tube dust collector not only improves the production environment at the hot air hood of the sintering machine but also increases the negative pressure at the inlet of the induced draft fan, providing conditions for the diversion of the warm exhaust gas in the second stage of the annular cooler (otherwise, the exhaust gas in the second stage would not easily mix into the exhaust gas pipeline in the third stage).

[0023] This invention designs a reliable adjustment method. By combining and coordinating the opening and closing of the first cooling fan, the second circulating fan, the third circulating fan, and the deflector valve, it can meet the requirements of different working conditions and achieve the "three simultaneous" benefits of sinter cooling, zero emission of waste gas, and efficient utilization of waste heat under various conditions.

[0024] This invention is particularly applicable to situations where three-stage series heat exchangers are used in sections III, IV, and V to ensure the cooling requirements of the annular cooler (the ore outlet temperature does not exceed the allowable value), while the exhaust gas temperature in section III does not exceed the upper limit of the allowable hot air temperature for hot air sintering. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a zero-emission waste gas combined with efficient waste heat utilization system for a sintering ring cooler.

[0026] In the diagram, 1. Circulating cooler; 2. Waste heat boiler; 3. First circulating fan; 4. Make-up cooling air duct; 5. Cold air valve; 6. First cooling fan; 7. Second circulating fan; 8. Third circulating fan; 9. Multi-tube dust collector; 10. Exhaust fan; 11. Air deflector; 12. Air deflector valve. Detailed Implementation

[0027] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0030] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Example 1

[0032] The present invention discloses a zero-emission synergistic waste heat utilization system for sintering ring cooler exhaust gas, comprising at least a ring cooler, a waste heat boiler, a first circulating fan, a first cooling fan, a second circulating fan, and a third circulating fan.

[0033] The annular cooler 1 is divided into sections I, II, III, IV and V according to the temperature of the sintered ore from high to low. The exhaust gas outlets of sections I and II of the annular cooler 1 are connected to the exhaust gas inlet of the waste heat boiler 2. The exhaust gas outlet of the waste heat boiler 2 is connected to the air inlet of the first circulating fan 3. The air outlet of the first circulating fan 3 is divided into two paths, which are respectively connected to the air box of section I and the air box of section II of the annular cooler 1 to form the flue gas circulation of sections I and II of the annular cooler.

[0034] The air inlet of the first cooling fan 6 is connected to the outdoor environment, drawing in natural air from the atmosphere; the air outlet of the first cooling fan 6 is connected to the V-section air box of the annular cooler 1; the V-section exhaust gas outlet of the annular cooler 1 is connected in sequence to the second circulating fan 7 and the IV-section air box of the annular cooler 1; the IV-section exhaust gas outlet of the annular cooler 1 is connected in sequence to the third circulating fan 8 and the III-section air box of the annular cooler 1; the III-section exhaust gas outlet of the annular cooler 1 is connected to the hot air hood of the sintering machine, sending medium-temperature exhaust gas above the material surface of the sintering machine for hot air sintering;

[0035] Example 2

[0036] As an improvement to the above embodiment, a multi-tube dust collector 9 and an induced draft fan 10 are sequentially installed along the exhaust gas flow on the pipeline after the mixing point of the III-stage exhaust gas outlet and the V-stage exhaust gas outlet of the annular cooler 1. The multi-tube dust collector 9 is used to remove dust particles in the exhaust gas, and the induced draft fan 10 is used to overcome the friction resistance along the exhaust gas pipeline to send the exhaust gas to the hot air hood of the sintering machine.

[0037] Example 3

[0038] As an improvement to the above embodiment, the exhaust gas outlet pipe of the second stage of the annular cooler 1 is connected to the inlet of the induced draft fan 10 through the deflector pipe 11; the deflector pipe 11 is provided with a deflector valve 12 for adjusting the amount of medium-temperature airflow deflected from the exhaust gas of the second stage of the annular cooler.

[0039] Example 4

[0040] As an improvement to the above embodiment, a supplementary cooling air pipe 4 is provided on the air inlet pipe of the first circulating fan 3. One end of the supplementary cooling air pipe 4 is connected to the outdoor environment, and the other end is connected to the air inlet pipe of the first circulating fan 3. A cooling air valve 5 is provided on the supplementary cooling air pipe 4 to supplement the air volume loss in the first and second stage exhaust gas circulation process of the circulating cooler 1.

[0041] In the above embodiments, both the cold air valve 5 and the deflector valve 12 are adjustable; the first circulating fan 3, the first cooling fan 6, the second circulating fan 7, and the third circulating fan 8 are all frequency converters.

[0042] The waste heat boiler 2 is a dual-pressure, dual-channel steam waste heat boiler. The high-temperature air inlet channel and the medium-temperature air inlet channel are respectively connected to the first-stage exhaust gas outlet and the second-stage exhaust gas outlet of the annular cooler 1. The waste heat boiler 2 generates high-pressure and low-pressure steam, which are used to drive the steam turbine to generate electricity or drive the sintering main exhaust fan.

[0043] Example 5

[0044] The above system operation method is as follows:

[0045] The high-quality waste heat from sections I and II of the annular cooler is recovered and utilized through waste heat boiler 2, and the first circulating fan 3 provides the power for the flue gas circulation of sections I and II of the annular cooler.

[0046] The relatively low-quality waste heat from sections III, IV, and V of the annular cooler is connected in series to achieve cascaded temperature increase, generating medium-temperature hot air at the outlet of section III that can be used for hot air sintering; the first cooling fan 6, the second circulating fan 7, and the third circulating fan 8 sequentially provide the exhaust gas flow head for each section.

[0047] Under most operating conditions, the deflector valve 12 does not need to be opened. The hot air required for hot air sintering can be generated by the three-stage series connection of the three-stage cooling fan (sections III, IV, and V). In cold weather or when the temperature of the ore entering the cooling fan is low, the first cooling fan 6, the second circulating fan 7, and the third circulating fan 8 operate with reduced air volume. At the same time, the deflector valve 12 is opened, and the medium-temperature hot exhaust gas from the outlet of the cooling fan (section II) is mixed with the exhaust gas from the cooling fan (section III) to compensate for the reduced exhaust gas flow rate at the outlet of the cooling fan (section III) and the possible low air temperature. This avoids the adverse effects of changes in the operating conditions of this system on the production of the sintering machine.

[0048] The present invention has been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described above. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Many other changes and modifications made without departing from the concept and scope of the present invention should be considered within the scope of protection of the present invention.

[0049] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0050] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A zero-emission synergistic waste heat utilization system for sintering ring cooler exhaust gas, characterized in that, It includes at least an annular cooler, a waste heat boiler, a first circulating fan, a first cooling fan, a second circulating fan, and a third circulating fan; The annular cooler is divided into sections I, II, III, IV, and V according to the temperature of the sintered ore from high to low. The exhaust gas outlets of sections I and II of the annular cooler are connected to the exhaust gas inlet of the waste heat boiler. The exhaust gas outlet of the waste heat boiler is connected to the air inlet of the first circulating fan. The air outlet of the first circulating fan is divided into two paths, which are respectively connected to the air box of section I and the air box of section II of the annular cooler, forming a flue gas circulation of sections I and II of the annular cooler. The air inlet of the first cooling fan is connected to the outdoor environment, drawing in natural air from the atmosphere; the air outlet of the first cooling fan is connected to the V-section air box of the annular cooler; the V-section exhaust gas outlet of the annular cooler is connected in sequence to the second circulating fan and the IV-section air box of the annular cooler; the IV-section exhaust gas outlet of the annular cooler is connected in sequence to the third circulating fan and the III-section air box of the annular cooler; and the III-section exhaust gas outlet of the annular cooler is connected to the hot air hood of the sintering machine.

2. The sintering ring cooler exhaust gas zero-emission synergistic waste heat high-efficiency utilization system as described in claim 1, characterized in that, The exhaust gas outlet pipeline of the annular cooler is equipped with a multi-tube dust collector and an induced draft fan in sequence along the exhaust gas flow path.

3. The sintering ring cooler exhaust gas zero-emission synergistic waste heat high-efficiency utilization system as described in claim 2, characterized in that, The exhaust gas outlet pipe of the second stage of the annular cooler is connected to the inlet of the induced draft fan through a deflector pipe.

4. The sintering ring cooler exhaust gas zero-emission synergistic waste heat high-efficiency utilization system as described in claim 3, characterized in that, The deflector pipe is equipped with a deflector valve, which is used to adjust the amount of medium-temperature air drawn in from the exhaust gas of the second stage of the annular cooler.

5. The sintering ring cooler exhaust gas zero-emission synergistic waste heat high-efficiency utilization system as described in claim 4, characterized in that, The first circulating fan is equipped with a supplementary cooling air duct on its air inlet pipe. One end of the supplementary cooling air duct is connected to the outdoor environment, and the other end is connected to the air inlet pipe of the first circulating fan. A cooling air valve is installed on the supplementary cooling air duct to supplement the air volume loss during the first and second stage exhaust gas circulation process of the circulating cooler.

6. The sintering ring cooler exhaust gas zero-emission synergistic waste heat high-efficiency utilization system as described in claim 5, characterized in that, The cold air valve and the deflector valve are adjustable.

7. The sintering ring cooler exhaust gas zero-emission synergistic waste heat high-efficiency utilization system as described in claim 1, characterized in that, The first circulating fan, the first cooling fan, the second circulating fan, and the third circulating fan are all frequency converters.

8. The sintering ring cooler exhaust gas zero-emission synergistic waste heat high-efficiency utilization system as described in claim 1, characterized in that, The waste heat boiler is a dual-pressure, dual-channel steam waste heat boiler. The high-temperature air inlet channel and the medium-temperature air inlet channel are respectively connected to the first-stage exhaust gas outlet and the second-stage exhaust gas outlet of the annular cooler. The waste heat boiler generates high-pressure and low-pressure steam, which are used to drive the steam turbine to generate electricity or drive the sintering main exhaust fan.

9. A method for zero-emission combined with efficient waste heat utilization of sintering ring cooler exhaust gas, characterized in that, The method is performed based on the system described in claim 1, and includes the following steps: The high-quality waste heat from sections I and II of the annular cooler is recovered and utilized through a waste heat boiler, and the first circulating fan provides the power for the flue gas circulation of sections I and II of the annular cooler. The relatively low-quality waste heat from sections III, IV, and V of the annular cooler is connected in series to achieve cascaded temperature increase, generating medium-temperature hot air at the outlet of section III that can be used for hot air sintering; the first cooling fan, the second circulating fan, and the third circulating fan sequentially provide the exhaust gas flow head for each section.

10. The method for zero-emission synergistic waste heat utilization of sintering ring cooler exhaust gas as described in claim 9, characterized in that, It also includes the following steps: In cold weather, or when the ore inlet temperature of the annular cooler is low, the first cooling fan, the second circulating fan, and the third circulating fan operate with reduced air volume. At the same time, the deflector valve is opened, and the medium-temperature hot exhaust gas from the outlet of the second stage of the annular cooler mixes with the exhaust gas from the third stage of the annular cooler to compensate for the reduced exhaust gas flow at the outlet of the third stage of the annular cooler and the possible low air temperature, thus avoiding the adverse effects of changes in the operating conditions of this system on the production of the sintering machine.

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