High-efficiency metallurgical flue gas waste heat utilization device and control method

Abstract

A kind of high-efficiency metallurgical flue gas waste heat utilization device and control method.Solve the problem of low power generation efficiency and easy to be corroded of existing waste heat boiler.It includes feedwater heater and waste heat boiler, the feedwater heater includes feedwater flue and first economizer, the waste heat boiler includes multiple smoke passage and steam drum, the outer wall of the smoke passage is provided with water cooling wall, the smoke passage is provided with second economizer, superheater group and water cooling screen inside, the water in the first economizer absorbs the heat of the flue gas of refining furnace and is connected with the second economizer in the waste heat boiler in series, the liquid in the steam drum flows back to the steam drum after passing through water cooling wall and water cooling screen, and then outputs medium-temperature medium-pressure steam after passing through superheater group, the outlet flue gas of the feedwater flue and the outlet flue gas of the smoke passage are connected with the same flue gas purification device.The present application utilizes two different physical properties of metallurgical high-temperature exhaust gas, and can produce medium-temperature medium-pressure steam, so the power generation efficiency is higher.

Description

Technical Field

[0001] This invention relates to a high-efficiency metallurgical flue gas waste heat utilization device and control method. Background Technology

[0002] To address climate change, energy conservation and emission reduction have become a global consensus. While creating social benefits, energy conservation and emission reduction are more importantly about reducing operating costs for enterprises, generating substantial economic benefits, and enhancing their green competitiveness. Waste heat boilers are a crucial piece of equipment in metallurgical plant production processes and a key technological means for reducing energy consumption and saving energy. Conventional metallurgical waste heat furnaces utilize only one type of flue gas, and the associated waste heat boilers typically only produce saturated steam or slightly superheated steam. This results in high boiler exhaust temperatures and low overall plant efficiency. Furthermore, these waste heat boilers often employ upper and lower flue systems or large cavity structures, leading to excessive height, large footprint, poor seismic resistance, or high construction costs. Moreover, these boilers generally only recover heat from one type of high-temperature flue gas, and due to the high sulfur dioxide content in the high-temperature flue gas generated during the smelting process, the flue gas dew point is high (approximately 220°C), making the boiler's tail-end heating surfaces prone to corrosion. Summary of the Invention

[0003] To address the problems of low power generation efficiency and susceptibility to corrosion in existing waste heat boilers, this invention provides a high-efficiency metallurgical flue gas waste heat utilization device and control method.

[0004] The technical solution of this invention is: a high-efficiency metallurgical flue gas waste heat utilization device, comprising a feedwater heater utilizing waste heat from flue gas of a metallurgical refining furnace and a waste heat boiler utilizing waste heat from flue gas of a metallurgical smelting furnace. The feedwater heater includes a feedwater flue and a first economizer. The waste heat boiler includes multiple flue gas passages and a steam drum. The outer wall of the flue gas passage is provided with a water-cooled wall. The flue gas passage is provided with a second economizer, a superheater group, and a water-cooled screen. The water in the first economizer absorbs the heat from the flue gas of the refining furnace and is connected in series with the second economizer in the waste heat boiler before entering the steam drum. The liquid in the steam drum flows back to the steam drum after passing through the water-cooled wall and the water-cooled screen, and then outputs medium-temperature and medium-pressure steam after passing through the superheater group. The outlet flue gas of the feedwater flue and the outlet flue gas of the flue gas passages are connected to the same flue gas purification device and share the same flue gas purification device.

[0005] As a further improvement of the present invention, the superheater group includes a low-temperature superheater, a medium-temperature superheater and a high-temperature superheater, wherein the high-temperature superheater, the medium-temperature superheater and the low-temperature superheater are connected in sequence and the low-temperature superheater is located near the outlet of the flue gas passage.

[0006] As a further improvement of the present invention, at least two of the low-temperature superheater, the medium-temperature superheater and the high-temperature superheater are provided, and the low-temperature superheater is arranged in parallel with the second economizer.

[0007] As a further improvement of the present invention, the flue includes a first flue, a second flue, a third flue, and a fourth flue, which are arranged sequentially, and the water-cooled wall is located outside the first flue, the second flue, the third flue, and the fourth flue.

[0008] As a further improvement of the present invention, the water-cooled screen is disposed in the third flue, and the superheater assembly is disposed in the fourth flue.

[0009] As a further improvement of the present invention, the second, third and fourth flues are provided with ash collection hoppers below them to facilitate the settling and recovery of precious metal fly ash, and the first, second, third and fourth flues cooperate with each other to form a back-and-forth bending shape.

[0010] As a further improvement of the present invention, the first flue and the second flue are provided with scorch holes, and the second flue and the third flue are provided with a vibrating mechanism.

[0011] As a further improvement of the present invention, a horizontal flue is provided at the tail end of the fourth flue, the second economizer is provided in the horizontal flue, and steam soot blowers are provided on the fourth flue and the horizontal flue.

[0012] As a further improvement of the present invention, the water supply flue is an insulated flue, and there are multiple first economizers arranged side by side at the outlet of the water supply flue.

[0013] A control method for a high-efficiency metallurgical flue gas waste heat utilization device, wherein the superheater group includes a low-temperature superheater, a medium-temperature superheater, and a high-temperature superheater, and the flue gas passage includes a first flue, a second flue, a third flue, and a fourth flue, the steps of which include: S1 connects the feedwater heater to the top of the refining furnace and introduces the high-temperature flue gas from the top-blown refining furnace outlet into the feedwater flue. S2 connects the waste heat boiler to the side of the smelting furnace and introduces the high-temperature flue gas from the oxygen-enriched side-blown smelting furnace into the flue gas passage. S3 connects the outlet of the water supply flue and the outlet of the flue gas passage to the same flue gas purification device. S4, using the 1200℃ high-temperature flue gas from the refining furnace outlet to heat the medium in the first economizer located in the feedwater flue, and then passing the medium into the second economizer; S5, the medium in the second economizer flows through the steam drum into the water-cooled wall and water-cooled screen, then returns to the steam drum and flows again through the low-temperature superheater, medium-temperature superheater and high-temperature superheater. S6 utilizes the high-temperature flue gas at 1450℃ from the outlet of the smelting furnace to heat the high-temperature superheater after passing through a water-cooled screen, and causes the medium in the high-temperature superheater to output medium-temperature and medium-pressure superheated steam at 4.0MPa and 400℃ for power generation. S7, the flue gas flowing through the high-temperature superheater continues to heat the medium-temperature superheater and the low-temperature superheater, and mixes with the flue gas from the feedwater heater, and is discharged after being treated by the same flue gas purification device.

[0014] The beneficial effects of this invention are: by utilizing two metallurgical high-temperature waste gases with different properties, medium-temperature and medium-pressure steam can be produced, resulting in higher power generation efficiency and more significant economic benefits; by directly feeding the hot working fluid from the feedwater heater outlet into the second economizer of the waste heat boiler, the wall temperature of the low-temperature section of the second economizer's heating surface is increased, which is more advantageous for utilizing high-sulfur corrosive waste gases, reducing low-temperature corrosion of the waste heat boiler economizer, increasing the service life of the waste heat boiler, and enabling cascade utilization of heat; this invention unifies the treatment of the two low-temperature flue gases after heat exchange, sharing a single environmental protection equipment, which helps save on construction and operating costs. This invention also has the advantages of simple structure, convenient assembly, reliable operation, and long service life. Attached Figure Description

[0015] Appendix Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0016] Appendix Figure 2 This is a schematic diagram of the water heater in an embodiment of the present invention.

[0017] Appendix Figure 3 This is a schematic diagram of the waste heat boiler in an embodiment of the present invention.

[0018] Appendix Figure 4 This is a schematic diagram of the control principle of an embodiment of the present invention.

[0019] In the diagram, 1. Feedwater heater; 2. Waste heat boiler; 3. Feedwater flue; 31. Insulated flue; 4. First economizer; 5. Flue gas passage; 51. First flue; 52. Second flue; 53. Third flue; 54. Fourth flue; 55. Coke hole; 56. Vibrating mechanism; 57. Horizontal flue; 58. Steam soot blower; 6. Steam drum; 7. Water-cooled wall; 8. Second economizer; 9. Superheater group; 91. Low-temperature superheater; 92. Medium-temperature superheater; 93. High-temperature superheater; 10. Water-cooled screen; 11. Ash collection hopper; 12. Refining furnace; 13. Smelting furnace. Detailed Implementation

[0020] The embodiments of the present invention will be further described below with reference to the accompanying drawings: Depend on Figure 1 Combination Figure 2-4As shown, a high-efficiency metallurgical flue gas waste heat utilization device includes a feedwater heater 1 that utilizes the waste heat of flue gas from a metallurgical refining furnace 12 and a waste heat boiler 2 that utilizes the waste heat of flue gas from a metallurgical smelting furnace 13. The feedwater heater 1 includes a feedwater flue 3 and a first economizer 4. Specifically, the feedwater flue 3 is an insulated flue 31, and there are multiple first economizers 4 arranged side by side at the outlet of the feedwater flue 3. The waste heat boiler 2 includes multiple flue gas passages 5 and a steam drum 6. The outer wall of the flue gas passage 5 is equipped with a water-cooled wall 7. The flue gas passage 5 is equipped with a second economizer 8, a superheater group 9 and a water-cooled screen 10. The water in the first economizer 4 absorbs the heat of the flue gas from the refining furnace 12 and is connected in series with the second economizer 8 in the waste heat boiler 2 before entering the steam drum 6. The liquid in the steam drum 6 flows back to the steam drum 6 after passing through the water-cooled wall 7 and the water-cooled screen 10, and then passes through the superheater group 9 before outputting medium-temperature and medium-pressure steam. The outlet flue gas of the feedwater flue 3 and the outlet flue gas of the flue gas passage 5 are connected to the same flue gas purification device and share the same flue gas purification device. The beneficial effects of this invention are: by utilizing two metallurgical high-temperature waste gases with different properties, medium-temperature and medium-pressure steam can be produced, resulting in higher power generation efficiency and more significant economic benefits; by directly feeding the hot working fluid from the feedwater heater outlet into the second economizer of the waste heat boiler, the wall temperature of the low-temperature section of the second economizer's heating surface is increased, which is more advantageous for utilizing high-sulfur corrosive waste gases, reducing low-temperature corrosion of the waste heat boiler economizer, increasing the service life of the waste heat boiler, and enabling cascade utilization of heat; this invention unifies the treatment of the two low-temperature flue gases after heat exchange, sharing a single environmental protection equipment, which helps save on construction and operating costs. This invention also has the advantages of simple structure, convenient assembly, reliable operation, and long service life. This invention utilizes two different high-temperature flue gas streams to heat the feedwater heater and waste heat boiler in stages, enabling the working fluid to be heated in stages. This significantly increases the feedwater temperature of the waste heat boiler, reduces corrosion on the tail-end heating surfaces of the waste heat boiler, extends the equipment's service life, and increases the power plant's economic efficiency. The multi-channel (flue gas passage) waste heat boiler design offers high heat recovery efficiency, a smaller boiler height and footprint, and maximizes the recovery of precious metals from the high-temperature flue gas used in smelting, producing medium-temperature, medium-pressure superheated steam for power generation. This improves power plant efficiency, enhances boiler safety and stability, increases precious metal recovery rates, and reduces power plant construction costs, resulting in comprehensive economic benefits. This invention patent discloses a high-efficiency metallurgical flue gas waste heat utilization device. This device can be used to recover the heat of high-temperature waste gas with different physical properties generated in two process stages of metal smelting, and produce medium-temperature and medium-pressure steam for power generation. By utilizing two metallurgical waste gases with different physical properties, the medium-temperature and medium-pressure steam produced has higher power generation efficiency and more significant economic benefits than conventional metallurgical waste heat furnaces with saturation parameters of 4.0MPa and 250℃ or slightly superheated parameters of 4.0MPa and 280℃.

[0021] The superheater group 9 includes a low-temperature superheater 91, a medium-temperature superheater 92, and a high-temperature superheater 93. These three superheaters are connected sequentially, with the low-temperature superheater 91 located near the outlet of the flue gas passage 5. Specifically, at least two of each of the three types are provided, with the low-temperature superheater 91 arranged parallel to the second economizer 8. The flue gas in the flue gas passage first passes through the high-temperature superheater, then the medium-temperature superheater, and finally the low-temperature superheater. This efficient use of flue gas temperature allows for stepped heating of the medium within the superheater group. Furthermore, the medium output from the high-temperature superheater group is used for power generation, resulting in higher power generation efficiency.

[0022] The flue gas passage is a multi-pass flue, comprising a first flue 51, a second flue 52, a third flue 53, and a fourth flue 54, arranged sequentially. A water-cooled wall 7 is located outside these four flues. The water-cooled wall effectively reduces the flue gas temperature at the inlet of the superheater assembly, preventing high-temperature corrosion. It also effectively distributes the flue gas flow and traps fly ash in the ash collection hopper. Specifically, the water-cooled wall 10 is located within the third flue 53, and the superheater assembly 9 is located within the fourth flue 54.

[0023] Below the second flue 52, third flue 53, and fourth flue 54, there are ash collection hoppers 11 to facilitate the settling and recovery of precious metal fly ash. The first flue 51, second flue 52, third flue 53, and fourth flue 54 cooperate with each other to form a back-and-forth bending shape. This structure facilitates the collection of ash (precious metals), especially for the recovery of precious metals contained in the flue gas of metal smelting and processing, reducing pollution and improving efficiency.

[0024] The first flue 51 and the second flue 52 are provided with coking holes 55, and the second flue 52 and the third flue 53 are provided with rapping mechanisms 56. Specifically, the tail end of the fourth flue 54 is provided with a horizontal flue 57, the second economizer 8 is located in the horizontal flue 57, and the fourth flue 54 and the horizontal flue 57 are provided with steam soot blowers 58. When implementing ash removal, this invention addresses the coking and ash accumulation in different parts by using manual coking removal, mechanical rapping ash removal, and steam flushing ash removal to quickly and efficiently remove coking and ash accumulation on the surface of the heating surface, thereby improving heat exchange efficiency.

[0025] A control method for a high-efficiency metallurgical flue gas waste heat utilization device, wherein the superheater group 9 includes a low-temperature superheater 91, a medium-temperature superheater 92, and a high-temperature superheater 93, and the flue gas passage 5 includes a first flue 51, a second flue 52, a third flue 53, and a fourth flue 54, the method comprising the following steps: S1, connect the feedwater heater 1 to the top of the refining furnace, and introduce the high-temperature flue gas from the top-blown refining furnace outlet into the feedwater flue 3; S2, connect the waste heat boiler 2 to the side of the smelting furnace, and introduce the high-temperature flue gas from the oxygen-enriched side-blown smelting furnace into the flue gas passage 5. S3 connects the outlet of the water supply flue 3 and the outlet of the smoke passage 5 to the same flue gas purification device. S4, using the 1200℃ high-temperature flue gas from the outlet of the refining furnace to heat the medium in the first economizer 4 located in the feedwater flue 3, and then passing the medium into the second economizer 8; S5, the medium in the second economizer 8 flows into the water-cooled wall 7 and water-cooled screen 10 after passing through the steam drum 6, and then returns to the steam drum 6 and flows again through the low-temperature superheater 91, the medium-temperature superheater 92 and the high-temperature superheater 93. S6 utilizes the high-temperature flue gas at 1450°C from the outlet of the smelting furnace to heat the high-temperature superheater 93 after passing through the water-cooled screen 10, and causes the medium inside the high-temperature superheater 93 to output medium-temperature and medium-pressure superheated steam at 4.0MPa and 400°C for power generation. S7, the flue gas flowing through the high-temperature superheater 93 continues to heat the medium-temperature superheater 92 and the low-temperature superheater 91, and mixes with the flue gas from the feedwater heater 1, and is discharged after being treated by the same flue gas purification device.

[0026] By adopting the above solution, the present invention has the following advantages: 1. Metallurgical processes may involve various melting furnaces and refining furnaces, generating a variety of flue gases. These flue gases have high sulfur content and high dew points, which easily corrode the boiler's tail-end heating surfaces, reducing equipment lifespan. Therefore, this invention uses a feedwater heater to heat feedwater from the top-blown refining furnace outlet flue gas for use in the waste heat boiler feedwater, increasing the feedwater temperature, improving the corrosion resistance of the tail-end heating surfaces, and extending equipment lifespan. Furthermore, the waste heat boiler utilizes the waste heat from the oxygen-enriched side-blown melting furnace outlet flue gas to produce superheated steam for power generation, achieving cascade utilization of metallurgical flue gas and improving the overall efficiency of flue gas waste heat utilization.

[0027] 2. This invention uses medium-temperature and medium-pressure superheated steam at 400℃ and 4.0MPa for power generation, which is different from the saturated steam parameters (250℃ and 4.0MPa) or slightly superheated parameters (280℃ and 4.0MPa) of the previous metallurgical waste heat furnace. This greatly improves the power generation efficiency and the economic benefits of the power plant.

[0028] 3. The present invention adopts a furnace arrangement with multiple vertical and horizontal flues, which can effectively carry out fly ash settling and recovery, reduce boiler height, and save construction costs.

[0029] 4. The waste heat boiler of this invention is equipped with multiple slag removal holes in the first and second flues, several layers of rapping devices in the second and third flues, and steam soot blowers in the fourth and horizontal flues. When removing ash, different methods are used to treat the slag and ash accumulation in different parts. By manually removing slag, mechanically rapping to remove ash, and steam flushing to remove slag and ash, the surface of the heating surface can be quickly and efficiently removed, thereby improving the heat exchange efficiency.

[0030] 5. The waste heat boiler of this invention has multiple water-cooled screens arranged in the third flue, which can effectively reduce the inlet flue gas temperature of the superheater, prevent the superheater from high temperature corrosion, and effectively distribute the flue gas flow and intercept fly ash to the ash hopper.

[0031] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0033] Please note to all technical personnel: Although the present invention has been described according to the specific embodiments above, the inventive concept of the present invention is not limited to this invention. Any modifications that utilize the inventive concept will be included within the scope of protection of this patent.

Claims

1. A high-efficiency metallurgical flue gas waste heat utilization device, characterized in that... The invention includes a feedwater heater (1) utilizing waste heat from flue gas of a metallurgical refining furnace (12) and a waste heat boiler (2) utilizing waste heat from flue gas of a metallurgical smelting furnace (13). The feedwater heater (1) includes a feedwater flue (3) and a first economizer (4). The waste heat boiler (2) includes multiple flue gas passages (5) and a steam drum (6). The outer wall of the flue gas passages (5) is provided with a water-cooled wall (7). The flue gas passages (5) are provided with a second economizer (8), a superheater group (9), and a water-cooled screen (10). The water in the first economizer (4) absorbs the heat of the flue gas from the refining furnace (12) and is connected in series with the second economizer (8) in the waste heat boiler (2), and then enters the steam drum (6). The liquid in the steam drum (6) flows back to the steam drum (6) after passing through the water-cooled wall (7) and the water-cooled screen (10), and then outputs medium-temperature and medium-pressure steam after passing through the superheater group (9). The outlet flue gas of the feedwater flue (3) and the outlet flue gas of the flue gas passage (5) are connected to the same flue gas purification device and share the same flue gas purification device.

2. The high-efficiency metallurgical flue gas waste heat utilization device according to claim 1, characterized in that... The superheater group (9) includes a low-temperature superheater (91), a medium-temperature superheater (92) and a high-temperature superheater (93). The high-temperature superheater (93), the medium-temperature superheater (92) and the low-temperature superheater (91) are connected in sequence and the low-temperature superheater (91) is close to the outlet of the flue gas passage (5).

3. The high-efficiency metallurgical flue gas waste heat utilization device according to claim 2, characterized in that... The low-temperature superheater (91), medium-temperature superheater (92) and high-temperature superheater (93) are each provided in at least two, and the low-temperature superheater (91) is arranged in parallel with the second economizer (8).

4. The high-efficiency metallurgical flue gas waste heat utilization device according to claim 1, characterized in that... The smoke passage (5) includes a first smoke passage (51), a second smoke passage (52), a third smoke passage (53), and a fourth smoke passage (54), which are arranged sequentially. The water-cooled wall (7) is located outside the first smoke passage (51), the second smoke passage (52), the third smoke passage (53), and the fourth smoke passage (54).

5. The high-efficiency metallurgical flue gas waste heat utilization device according to claim 4, characterized in that... The water-cooled screen (10) is located in the third flue (53), and the superheater group (9) is located in the fourth flue (54).

6. The high-efficiency metallurgical flue gas waste heat utilization device according to claim 4, characterized in that... Below the second flue (52), the third flue (53), and the fourth flue (54) is a ash collection hopper (11) to facilitate the settling and recovery of precious metal fly ash. The first flue (51), the second flue (52), the third flue (53), and the fourth flue (54) cooperate with each other to form a back-and-forth bending shape.

7. The high-efficiency metallurgical flue gas waste heat utilization device according to claim 4, characterized in that... The first flue (51) and the second flue (52) are provided with scorch holes (55), and the second flue (52) and the third flue (53) are provided with a vibrating mechanism (56).

8. The high-efficiency metallurgical flue gas waste heat utilization device according to claim 4, characterized in that... The fourth flue (54) is provided with a horizontal flue (57) at its tail end. The second economizer (8) is located in the horizontal flue (57). Steam soot blowers (58) are provided on the fourth flue (54) and the horizontal flue (57).

9. The high-efficiency metallurgical flue gas waste heat utilization device according to claim 1, characterized in that... The water supply flue (3) is an insulated flue (31), and there are multiple first economizers (4) arranged side by side at the outlet of the water supply flue (3).

10. A control method for a high-efficiency metallurgical flue gas waste heat utilization device according to any one of claims 1-9, characterized in that: The superheater group (9) includes a low-temperature superheater (91), a medium-temperature superheater (92), and a high-temperature superheater (93). The flue gas passage (5) includes a first flue (51), a second flue (52), a third flue (53), and a fourth flue (54). The steps include: S1, connect the feedwater heater (1) to the top of the refining furnace and introduce the high-temperature flue gas from the top-blown refining furnace outlet into the feedwater flue (3). S2, connect the waste heat boiler (2) to the side of the smelting furnace, and pass the high-temperature flue gas from the outlet of the oxygen-enriched side-blown smelting furnace into the flue gas passage (5). S3, connect the outlet of the water supply flue (3) and the outlet of the smoke passage (5) to the same flue gas purification device; S4, using the 1200℃ high-temperature flue gas from the outlet of the refining furnace to heat the medium in the first economizer (4) located in the water supply flue (3), and then passing the medium into the second economizer (8); S5, the medium in the second economizer (8) flows into the water-cooled wall (7) and water-cooled screen (10) after passing through the steam drum (6), and then returns to the steam drum (6) and flows through the low-temperature superheater (91), medium-temperature superheater (92) and high-temperature superheater (93) again. S6, using the high-temperature flue gas at 1450°C from the outlet of the smelting furnace to heat the high-temperature superheater (93) after passing through the water-cooled screen (10), and causing the medium in the high-temperature superheater (93) to output medium-temperature and medium-pressure superheated steam at 4.0MPa and 400°C for power generation. S7, the flue gas flowing through the high-temperature superheater (93) continues to heat the medium-temperature superheater (92) and the low-temperature superheater (91), and mixes with the flue gas from the feedwater heater (1), and is discharged after being treated by the same flue gas purification device.

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