An intermediate once-reheat gas boiler for efficiently recovering waste heat from a circular cooler

Abstract

The application discloses a kind of intermediate primary reheat gas boiler of high-efficiency recovery of waste heat of circular cooler exhaust gas.In the boiler, combustion chamber, high-temperature bypass area, high-temperature heat exchange area, first-stage mixing area, medium-temperature heat exchange area, second-stage mixing area, low-temperature heat exchange area are sequentially arranged according to the flow direction of flue gas temperature in the boiler;Wherein, 1000-1600 ℃ high-temperature flue gas generated by gas combustion in the combustion chamber is divided into two flues and enters the high-temperature bypass area and the high-temperature heat exchange area;After passing through the high-temperature heat exchange area and the high-temperature bypass area, the temperature is reduced to 500-700 ℃ and enters the first-stage mixing area;Mixed with 300-500 ℃ high-temperature exhaust gas of the circular cooler I area, the mixed flue gas enters the high-pressure evaporator 502 and the high-pressure economizer 501 in turn, and the flue gas temperature is reduced to 200-300 ℃ and enters the second-stage mixing area, and then mixed with 200-300 ℃ low-temperature exhaust gas discharged from the circular cooler II area, the mixed flue gas enters the low-pressure evaporator 702 and the low-pressure economizer 701 in turn, and the flue gas temperature is reduced to 100-180 ℃ and discharged from the boiler.

Description

Technical Field

[0001] This invention relates to an intermediate reheat gas boiler for efficiently recovering waste heat from the exhaust gas of an annular cooler. Background Technology

[0002] Currently, steel plants recover energy from coal gas and waste heat from sintering ring coolers by setting up separate coal gas boilers and waste heat boilers to recover energy and generate steam. This method has low energy utilization efficiency, especially since the low-temperature energy utilization efficiency of the ring cooler is extremely low. It is mostly used to generate one or more streams of low-pressure steam, resulting in low power generation quality. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides an intermediate reheat gas boiler that efficiently recovers waste heat from the exhaust gas of an annular cooler. By burning gas, high-temperature hot flue gas is generated. The heating surfaces are rationally arranged to fully utilize the low-temperature waste heat of the annular cooler to generate saturated steam, and the high-temperature flue gas generated from burning gas is used to generate superheated steam, thereby improving the quality of steam power generation.

[0004] To achieve the above objectives, the present invention provides an intermediate reheat gas boiler for efficient recovery of waste heat from the exhaust gas of an annular cooler. The boiler is provided with a combustion chamber, a high-temperature bypass zone, a high-temperature heat exchange zone, a first-stage mixing zone, a medium-temperature heat exchange zone, a second-stage mixing zone, and a low-temperature heat exchange zone arranged sequentially according to the flow direction of the flue gas temperature.

[0005] Among them, the high-temperature flue gas of 1000-1600℃ generated by the combustion of coal gas in the combustion chamber enters the high-temperature bypass zone and the high-temperature heat exchange zone through two flues respectively.

[0006] After passing through the high-temperature heat exchange zone and the high-temperature bypass zone, the temperature drops to 500-700℃ and enters the first mixing zone. It mixes with the 300-500℃ high-temperature exhaust gas from the annular cooler I zone. The mixed flue gas then enters the high-pressure evaporator 502 and the high-pressure economizer 501 in sequence, where the flue gas temperature drops to 200-300℃ and enters the second mixing zone. It then mixes with the 200-300℃ low-temperature exhaust gas discharged from the annular cooler II zone. The mixed flue gas then enters the low-pressure evaporator 702 and the low-pressure economizer 701 in sequence, where the flue gas temperature drops to 100-180℃ before being discharged from the boiler.

[0007] Furthermore, the high-temperature heat exchange zone includes a reheater and a superheater.

[0008] Furthermore, the high-temperature bypass zone includes: a high-pressure bypass evaporator and a flue gas regulating baffle.

[0009] Furthermore, the medium-temperature heat exchange zone includes: a high-pressure economizer and a high-pressure evaporator.

[0010] Furthermore, the low-temperature heat exchange zone includes: a low-pressure economizer and a low-pressure evaporator.

[0011] Furthermore, the high-temperature heat exchange zone has three interfaces, which are respectively connected to the outlet of the first-stage exhaust gas regulating valve, the outlet of the second-stage exhaust gas regulating valve, and the outlet of the air regulating valve.

[0012] Furthermore, the high-temperature heat exchange zone includes a reheater and a superheater; the high-temperature bypass zone includes a high-pressure bypass evaporator and a flue gas regulating baffle; the method for controlling the outlet steam temperature of the superheater and reheater includes:

[0013] The amount of flue gas flowing into the high-temperature bypass zone is adjusted by regulating the flue gas regulating damper: when the outlet steam temperature of the superheater and reheater is ≥580℃, the opening of the flue gas regulating damper increases, increasing the amount of flue gas passing through the high-temperature bypass zone and decreasing the amount of flue gas passing through the high-temperature heat exchange zone, thereby reducing the heat absorption of the superheater and reheater and lowering the outlet steam temperature.

[0014] Furthermore, methods for controlling the outlet steam temperature of the superheater and reheater include:

[0015] When the outlet steam temperature of superheater 302 and reheater 301 is ≥580℃, adjust the flow rate of exhaust gas from zone I and / or zone II of the annular cooler into the high-temperature heat exchange zone.

[0016] This invention utilizes high-quality coal gas resources and adopts a reasonable steam-water process to fully improve the power generation quality of the waste heat from the annular cooler. At the same time, considering the large fluctuations in the two types of waste heat resources in steel plants, flue gas damper regulation and three-stream exhaust gas flow regulation are adopted to control the temperature of the superheated steam generated by the superheater and reheater, ensuring the safe and stable operation of the intermediate reheat coal gas boiler. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of an intermediate reheat gas boiler that efficiently recovers waste heat from the exhaust gas of an annular cooler.

[0018] 1. Combustion chamber; 2. High-temperature bypass zone; 3. High-temperature heat exchange zone; 4. First-stage mixing zone; 5. Medium-temperature heat exchange zone; 6. Second-stage mixing zone; 7. Low-temperature heat exchange zone; 8. Air regulating valve; 9. First-stage exhaust gas regulating valve; 10. Second-stage exhaust gas regulating valve; 11. Burner; 201. High-pressure bypass evaporator; 202. Flue gas regulating damper; 301. Reheater; 302. Superheater; 501. High-pressure economizer; 502. High-pressure evaporator; 701. Low-pressure economizer; 702. Low-pressure evaporator. Detailed Implementation

[0019] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] like Figure 1 As shown, this embodiment is a process of using high-temperature flue gas generated by burning coal gas to superheat high-pressure saturated steam generated by replacing the waste heat of low-temperature annular cooler, and then reheating the low-pressure saturated steam.

[0024] The waste heat comprehensive utilization system in this embodiment includes: 1. Combustion chamber; 2. High-temperature bypass zone; 3. High-temperature heat exchange zone; 4. First-stage mixing zone; 5. Medium-temperature heat exchange zone; 6. Second-stage mixing zone; 7. Low-temperature heat exchange zone; 8. Air regulating valve; 9. First-stage exhaust gas regulating valve; 10. Second-stage exhaust gas regulating valve; 11. Burner; 201. High-pressure bypass evaporator; 202. Flue gas regulating baffle; 301. Reheater; 302. Superheater; 501. High-pressure economizer; 502. High-pressure evaporator; 701. Low-pressure economizer; 702. Low-pressure evaporator.

[0025] Example 1

[0026] The intermediate reheat gas boiler for high-efficiency recovery of waste heat from the annular cooler in this embodiment is provided with a combustion chamber, a high-temperature bypass zone, a high-temperature heat exchange zone, a first-stage mixing zone, a medium-temperature heat exchange zone, a second-stage mixing zone, and a low-temperature heat exchange zone arranged sequentially in accordance with the flow direction of the flue gas temperature in the boiler.

[0027] Among them, the high-temperature flue gas of 1000-1600℃ generated by the combustion of coal gas in the combustion chamber enters the high-temperature bypass zone and the high-temperature heat exchange zone through two flues respectively.

[0028] After passing through the high-temperature heat exchange zone and the high-temperature bypass zone, the temperature drops to 500-700℃ and enters the first mixing zone. It mixes with the 300-500℃ high-temperature exhaust gas from the annular cooler I zone. The mixed flue gas then enters the high-pressure evaporator 502 and the high-pressure economizer 501 in sequence, where the flue gas temperature drops to 200-300℃ and enters the second mixing zone. It then mixes with the 200-300℃ low-temperature exhaust gas discharged from the annular cooler II zone. The mixed flue gas then enters the low-pressure evaporator 702 and the low-pressure economizer 701 in sequence, where the flue gas temperature drops to 100-180℃ before being discharged from the boiler.

[0029] Example 2

[0030] Based on the above embodiments, the high-temperature heat exchange zone includes a reheater and a superheater.

[0031] Example 3

[0032] Based on the above embodiments, the high-temperature bypass zone includes: a high-pressure bypass evaporator and a flue gas regulating baffle.

[0033] Example 4

[0034] Based on the above embodiments, the medium-temperature heat exchange zone includes: a high-pressure economizer and a high-pressure evaporator.

[0035] Example 5

[0036] Based on the above embodiments, the low-temperature heat exchange zone includes: a low-pressure economizer and a low-pressure evaporator.

[0037] The invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0038] This embodiment is divided into two parts: a combustion system and a flue gas system.

[0039] Combustion system: The remaining coal gas in the steel plant is transported through pipelines to burner 11 for combustion, producing high-temperature flue gas (1000~1600℃).

[0040] Flue gas system: The high-temperature flue gas (1000-1600℃) generated by coal gas combustion enters the high-temperature bypass zone 2 and the high-temperature heat exchange zone 3 through two flues. After passing through the superheater 302 and reheater 301 in the high-temperature heat exchange zone 3, and the flue gas regulating baffle 202 and high-pressure bypass evaporator 201 in the high-temperature bypass zone, the temperature drops to 500-700℃ and enters the first mixing zone 4, where it mixes with the high-temperature exhaust gas (300-500℃) from the annular cooler I zone. The mixed flue gas then enters the high-pressure evaporator 502 and the high-pressure economizer 501 in sequence, where the flue gas temperature drops to 200-300℃ and enters the second mixing zone. It then mixes with the low-temperature exhaust gas (200-300℃) discharged from the annular cooler II zone. The mixed flue gas then enters the low-pressure evaporator 702 and the low-pressure economizer 701 in sequence, where the flue gas temperature drops to 100-180℃ before being discharged from the boiler.

[0041] Example 6

[0042] Because the amount of gas fluctuates greatly with the amount of exhaust gas from the annular cooler, the outlet steam temperature of the superheater 302 and reheater 301 is difficult to control. The present invention can control the outlet steam temperature of the superheater 302 and reheater 301 through the following four methods.

[0043] Method 1: Adjust the amount of flue gas flowing into the high-temperature bypass zone 2 by adjusting the flue gas regulating baffle 202: When the outlet steam temperature of the superheater 302 and reheater 301 is too high (≥580℃), the opening of the flue gas regulating baffle 202 increases, increasing the amount of flue gas passing through the high-temperature bypass zone 2 and decreasing the amount of flue gas passing through the high-temperature heat exchange zone 3, thereby reducing the heat absorption of the superheater 302 and reheater 301 and lowering the outlet steam temperature;

[0044] Method 2: When the outlet steam temperature of superheater 302 and reheater 301 is too high, adjust the opening of the first-stage waste gas regulating valve 9 to increase the flow rate of the first-stage waste gas entering the high-temperature heat exchange zone 3. Since the temperature of the first-stage waste gas (300-500℃) is lower than the flue gas temperature (1000-1600℃), increasing the flow rate of the first-stage waste gas will reduce the flue gas temperature, thereby reducing the outlet steam temperature of superheater 302 and reheater 301.

[0045] Method 3: When the outlet steam temperature of superheater 302 and reheater 301 is too high, adjust the opening of the second-stage exhaust gas regulating valve 10 to increase the flow rate of the second-stage exhaust gas entering the high-temperature heat exchange zone 3. Since the temperature of the second-stage exhaust gas (200-300℃) is lower than the flue gas temperature (1000-1600℃), increasing the flow rate of the second-stage exhaust gas will reduce the flue gas temperature, thereby reducing the outlet steam temperature of superheater 302 and reheater 301.

[0046] Method 4: When the outlet steam temperature of superheater 302 and reheater 301 is too high, adjust the opening of air regulating valve 8 to increase the air flow into high-temperature heat exchange zone 3. Since the air temperature (~20℃) is lower than the flue gas temperature (1000~1600℃), increasing the air flow will reduce the flue gas temperature, thereby reducing the outlet steam temperature of superheater 302 and reheater 301.

[0047] This invention utilizes the high-temperature flue gas generated by coal gas combustion to fully recover and improve the waste heat quality of the low-temperature exhaust gas after the sintered ore is cooled on the annular cooler. In accordance with the second law of thermodynamics, the heating surfaces in the boiler are rationally arranged to recover the waste heat of the flue gas in the tail flue in stages. The intermediate reheat steam technology is adopted to improve the quality of steam power generation. At the same time, four superheated steam temperature regulation methods are adopted to ensure the safe and stable operation of the boiler.

[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 high-efficiency intermediate reheat gas boiler for recovering waste heat from an annular cooler exhaust gas, characterized in that: The boiler is arranged in sequence according to the flow direction of the flue gas temperature, including combustion chamber, high temperature bypass zone, high temperature heat exchange zone, primary mixing zone, medium temperature heat exchange zone, secondary mixing zone, and low temperature heat exchange zone. Among them, the high-temperature flue gas of 1000~1600℃ generated by the combustion of coal gas in the combustion chamber enters the high-temperature bypass zone and the high-temperature heat exchange zone through two flues respectively. After passing through the high-temperature heat exchange zone and the high-temperature bypass zone, the temperature drops to 500~700℃ and enters the first mixing zone. It mixes with the 300~500℃ high-temperature exhaust gas from the annular cooler I zone. The mixed flue gas then enters the high-pressure evaporator and the high-pressure economizer in sequence, where the flue gas temperature drops to 200~300℃ and enters the second mixing zone. In the second mixing zone, it mixes with the 200~300℃ low-temperature exhaust gas discharged from the annular cooler II zone. The mixed flue gas then enters the low-pressure evaporator and the low-pressure economizer in sequence, where the flue gas temperature drops to 100~180℃ before being discharged from the boiler.

2. The intermediate reheat gas boiler for high-efficiency recovery of waste heat from annular cooler exhaust gas as described in claim 1, characterized in that: The high-temperature heat exchange zone includes a reheater and a superheater.

3. The intermediate reheat gas boiler for high-efficiency recovery of waste heat from annular cooler exhaust gas as described in claim 1, characterized in that: The high-temperature bypass zone includes: high-pressure bypass evaporator and flue gas regulating damper.

4. The intermediate reheat gas boiler for high-efficiency recovery of waste heat from annular cooler exhaust gas as described in claim 1, characterized in that: The medium-temperature heat exchange zone includes: a high-pressure economizer and a high-pressure evaporator.

5. The intermediate reheat gas boiler for high-efficiency recovery of waste heat from annular cooler exhaust gas as described in claim 1, characterized in that: The low-temperature heat exchange zone includes: a low-pressure economizer and a low-pressure evaporator.

6. The intermediate reheat gas boiler for high-efficiency recovery of waste heat from annular cooler exhaust gas as described in claim 1, characterized in that: The high-temperature heat exchange zone has three interfaces, which are respectively connected to the outlet of the first-stage exhaust gas regulating valve, the outlet of the second-stage exhaust gas regulating valve, and the outlet of the air regulating valve.

7. The intermediate reheat gas boiler for high-efficiency recovery of waste heat from annular cooler exhaust gas as described in claim 1, characterized in that: The high-temperature heat exchange zone includes a reheater and a superheater; the high-temperature bypass zone includes a high-pressure bypass evaporator and a flue gas regulating damper; the method for controlling the outlet steam temperature of the superheater and reheater includes: The amount of flue gas flowing into the high-temperature bypass zone is adjusted by regulating the flue gas regulating damper: when the outlet steam temperature of the superheater and reheater is ≥580℃, the opening of the flue gas regulating damper increases, increasing the amount of flue gas passing through the high-temperature bypass zone and decreasing the amount of flue gas passing through the high-temperature heat exchange zone, thereby reducing the heat absorption of the superheater and reheater and lowering the outlet steam temperature.

8. The intermediate reheat gas boiler for high-efficiency recovery of waste heat from annular cooler exhaust gas as described in claim 1, characterized in that: Methods for controlling the outlet steam temperature of superheaters and reheaters include: When the outlet steam temperature of the superheater and reheater is ≥580℃, adjust the flow rate of the exhaust gas from Zone I and / or Zone II of the annular cooler into the high-temperature heat exchange zone.

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