Sintering ring cold flue gas comprehensive recovery and recycling system

Abstract

This application discloses a comprehensive recovery and recycling system for sintering flue gas, relating to the fields of waste heat recovery and ultra-low emission energy saving in sintering flue gas. It includes a sintering machine, a flue gas cooler, and an internal circulation system. The sintering machine comprises at least a first section and a second section. The flue gas outlet of the first section is connected to the internal circulation system, and the flue gas outlet of the second section is connected to the internal circulation system via a flue boiler. The flue gas cooler includes multiple flue gas coolers. The hood of the flue gas cooler in the first section is connected to the air inlet of the adjacent flue gas cooler to form a closed-loop recycling path for low-temperature flue gas. The hood of the flue gas cooler in the second section is connected to the internal circulation system via pipelines, and the hood of the flue gas cooler in the third section is connected to an external waste heat boiler. This application achieves multiple objectives of energy saving and carbon reduction, waste heat value-added power generation, and ultra-low emission of flue gas in the sintering system through selective and precise diversion of sintering flue gas, dynamic control of the circulation ratio, and cascaded resource utilization of flue gas.

Description

Technical Field

[0001] This application relates to the field of sintering flue gas waste heat recovery and ultra-low emission energy-saving technology, and in particular to a comprehensive recovery and recycling system for sintering ring cold flue gas. Background Technology

[0002] The sintering machine and the annular cooler generate a large amount of gradient flue gas during operation, which is a key target for waste heat utilization and environmental emission reduction in the sintering process. The temperature, composition, and oxygen content of the flue gas in the sintering machine's air box vary greatly along the length of the machine. Traditional processes often use a fixed-ratio circulation method without selection, which easily leads to problems such as oxygen deficiency in the sintering bed, uneven combustion, and deviation of the sintering endpoint, resulting in extremely poor adaptability to operating conditions.

[0003] In terms of environmental protection and equipment configuration, the existing process only recovers medium and high temperature flue gas from the ring cooling system, while low temperature flue gas is directly discharged for a long time, making it impossible to achieve near-zero emissions from the ring cooling system and putting great pressure on environmental governance. Moreover, traditional waste heat recovery mostly uses independent waste heat boilers, which occupy a large space, are difficult to arrange on site, and have high infrastructure and operation and maintenance investment costs, resulting in poor economic efficiency for retrofitting and making it difficult to adapt to the compact retrofitting scenarios of existing sintering systems.

[0004] The ring cooler creates a stable temperature gradient in its partitions. However, existing technologies do not combine the ring cooler exhaust gas with graded utilization, making it impossible to simultaneously meet the multiple demands of ultra-low emissions, flexible production, and low-cost energy saving. Summary of the Invention

[0005] In view of this, this application provides a comprehensive recovery and recycling system for sintering annular cooling flue gas. Its main purpose is to address the shortcomings of existing sintering flue gas systems, such as unreasonable internal gas extraction, easy interference with sintering production, low waste heat utilization, rigid circulation control, large investment and land occupation of waste heat boilers, and direct discharge of low-temperature flue gas causing pollution. This application achieves precise internal circulation by selectively choosing the head and tail wind boxes of the sintering system. While ensuring normal sintering production reactions and stable product quality, it also achieves carbon emission reduction. Combined with the cascade resource utilization of annular cooling flue gas, it simultaneously achieves multiple goals of energy saving and carbon reduction in the sintering system, waste heat-based power generation, and ultra-low emissions of flue gas.

[0006] To solve the above problems, this application provides the following technical solution: A comprehensive recovery and recycling system for sintering ring cooler flue gas includes: a sintering machine, a ring cooler, and an internal circulation system; The sintering machine includes at least a first section and a second section. The flue gas outlet of the first section is connected to the internal circulation system, and the flue gas outlet of the second section is connected to the internal circulation system via the flue boiler. The annular cooler includes multiple annular cooler fans. The hood of the annular cooler fan located in the first stage of the annular cooler is connected to the air inlet of the adjacent annular cooler fan to form a closed-loop flue gas recycling path in the first stage of the annular cooler. The hood of the annular cooler fan located in the second stage of the annular cooler is connected to the internal circulation system through pipelines. The hood of the annular cooler fan located in the third stage of the annular cooler is connected to an external waste heat boiler.

[0007] Furthermore, the internal circulation system includes: an internal circulation fan, an annular cooling induced draft fan, a dust collector, and an air mixer; The flue gas in the first section enters the mixer after passing through the internal circulation fan; The flue gas in the second section passes sequentially through the flue boiler, the dust collector, and the internal circulation fan before entering the air mixer; The flue gas from the annular cooling fan in the second stage of the annular cooling system enters the air mixer via the annular cooling induced draft fan. The air mixer is used to mix the incoming flue gas and return the mixed air to the material surface of the sintering machine.

[0008] Furthermore, the annular cooler includes five annular cooling fans, namely, annular cooling fan #1, annular cooling fan #2, annular cooling fan #3, annular cooling fan #4 and annular cooling fan #5; The fume hood of the No. 5 ring cooler is connected in series to the air inlet of the No. 4 ring cooler, and the fume hood of the No. 4 ring cooler is connected in series to the air inlet of the No. 3 ring cooler, forming a closed-loop reuse path for the first stage of the ring cooler.

[0009] Furthermore, the hoods of the No. 1 and No. 2 annular air coolers are connected to the external waste heat boiler via pipelines to send the flue gas from the annular air coolers into the external waste heat boiler to produce steam.

[0010] Furthermore, the first section is located in the head bellows area of ​​the sintering machine, and the flue gas output from the head bellows area contains carbon monoxide; the second section is located in the tail bellows area of ​​the sintering machine.

[0011] Furthermore, the flue boiler is installed on the main flue pipe of the sintering machine to exchange heat with the flue gas discharged from the second section in order to recover heat.

[0012] Furthermore, the exhaust port of the air mixer is connected to the return air duct, and the return air duct delivers the mixed air to the material surface of the sintering machine to provide combustion-supporting gas for the sintering process.

[0013] Furthermore, the flue gas temperature in the first section is 70℃~90℃, and the flue gas temperature in the second section is 350℃~450℃.

[0014] Furthermore, after the flue gas in the second section is cooled by heat exchange in the flue boiler, it flows sequentially along the flue to the dust collector, the internal circulation fan, and then to the air mixer.

[0015] Furthermore, the fume hood of the No. 3 annular cooling fan is connected to an independent annular cooling second-stage branch, and the annular cooling second-stage branch is connected to the air mixer through the annular cooling induced draft fan.

[0016] This application constructs an integrated process system for selective and precise diversion and circulation of sintering flue gas at the head and tail ends, dynamically adjustable proportions, multi-stage cascade closed-loop ring-cooled fans, coupled air distribution of sintering-ring-cooled dual-source flue gas, and graded recovery of waste heat in stages.

[0017] This application abandons the conventional flue gas internal circulation mode and selects a portion of the exhaust gas from the sintering head and tail to enter the circulation. The flue gas circulation ratio is controlled at 15%~40% and can be dynamically adjusted according to the production load. The sintering flue integrated boiler is used to replace the independent waste heat boiler, which greatly reduces the footprint, simplifies the on-site pipeline layout, and effectively reduces project investment and operation and maintenance costs.

[0018] This application utilizes flue gas in a differentiated, tiered manner according to the temperature zones of the sintering ring; low-temperature flue gas is fully recycled in a closed loop, completely eliminating fugitive direct emissions and achieving near-zero emissions from the sintering ring; medium-temperature flue gas is fed into the sintering system to participate in the internal flue gas circulation; and high-temperature flue gas is introduced into the waste heat system for power generation, forming a graded and efficient utilization model of "low-temperature absorption and emission reduction, medium-temperature circulation to aid combustion, and high-temperature steam generation for power generation," which simultaneously improves the comprehensive utilization rate of sintering production cycle and flue gas waste heat, and has multiple benefits including energy saving, carbon reduction, and ultra-low emissions. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the process flow of an embodiment of this application; In the diagram: 1-Sintering machine, 101-First section, 102-Second section, 2-Annular cooler, 201-1# Annular cooler fan, 202-2# Annular cooler fan, 203-3# Annular cooler fan, 204-4# Annular cooler fan, 205-5# Annular cooler fan, 3-Internal circulation fan, 4-Annular cooler induced draft fan, 5-Dust collector, 6-Mixing air mixer, 7-Flue boiler. Detailed Implementation

[0020] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0021] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] The components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application.

[0023] Example 1 See Figure 1 This is a schematic diagram of the process flow of Embodiment 1 of this application. A comprehensive recovery and recycling system for sintering ring-cooled flue gas includes: a sintering machine 1, a ring cooler 2, and an internal circulation system. The sintering machine 1 includes at least a first section 101 and a second section 102. The flue gas outlet of the first section 101 is connected to the internal circulation system, and the flue gas outlet of the second section 102 is connected to the internal circulation system through a flue boiler 7. The ring cooler 2 includes multiple ring-cooled fans. The hood of the ring-cooled fan located in the first ring-cooling section is connected to the air inlet of the adjacent ring-cooled fan to form a closed-loop recycling path for the flue gas in the first ring-cooling section. The hood of the ring-cooled fan located in the second ring-cooling section is connected to the internal circulation system through a pipeline, and the hood of the ring-cooled fan located in the third ring-cooling section is connected to an external waste heat boiler.

[0024] In this embodiment, exhaust gas from the head and tail sections of the sintering machine's 1#~20# gas collection boxes is selected to enter the internal circulation system. Branch lines are selectively set up at the head section (4#, 5#, 6#) and the tail section (17#, 18#, 19#, 20#) to serve as the internal circulation gas source. The head section (4#, 5#, 6#) is designated as section 101, and the tail section (17#, 18#, 19#, 20#) is designated as section 102. Section 101 has a higher CO concentration in its exhaust gas; recycling allows for the secondary combustion of incompletely burned CO, reducing the CO concentration in the exhaust gas and achieving source emission reduction. Section 101 has a lower exhaust gas temperature (70℃~90℃), while section 102 has a higher temperature (350℃~450℃). As a further preferred option, the flue gas temperature in the second section 102 is 400℃. The flue gas in the second section 102 first undergoes heat exchange in the flue boiler 7 before entering the internal circulation system. Furthermore, the flue gas in the second section 102 has a high oxygen content, and its reuse can precisely supplement the oxygen required for sintering combustion, improving fuel combustion efficiency. The flue gas temperature in the second section 102 is controlled by adjusting the opening of the straight pipe valves in the head and tail divertable air boxes, combined with real-time adjustment of the diversion ratio based on the sintering machine's production load, material layer temperature, and furnace oxygen content, thus stably controlling the total flue gas circulation ratio within the range of 15% to 40%. The process design of this application achieves selective and precise diversion of sintering flue gas and dynamic control of the circulation ratio.

[0025] Example 2 Based on the above embodiments, the internal circulation system includes: an internal circulation fan 3, an annular cooling induced draft fan 4, a dust collector 5, and a mixer 6; the flue gas in the first section 101 enters the mixer 6 through the internal circulation fan 3; the flue gas in the second section 102 enters the mixer 6 through the flue boiler 7, the dust collector 5, and the internal circulation fan 3 in sequence; the flue gas from the annular cooling fan in the second annular cooling section enters the mixer 6 through the annular cooling induced draft fan 4; the mixer 6 is used to mix the incoming flue gas and return the mixed air to the material surface of the sintering machine 1.

[0026] Specifically, the internal circulation system may include an internal circulation fan 3, an annular cooling induced draft fan 4, a dust collector 5, and a mixer 6. The mixer 6 can be a container or pipeline assembly that uniformly mixes the gas, specifically a duct mixer or a box-type mixer. The mixer 6 is more preferably a duct mixer, which has a baffle plate inside to facilitate uniform mixing of the flue gas.

[0027] As a further preferred embodiment, the first section 101 is located in the head bellows area of ​​the sintering machine 1, and the flue gas output from the head bellows area contains carbon monoxide; the second section 102 is located in the tail bellows area of ​​the sintering machine 1. The flue gas in the second section 102 has a high temperature and high oxygen content, and its reuse can accurately replenish the oxygen required for sintering combustion, improving fuel combustion efficiency. After being cooled by heat exchange in the flue boiler 7, the flue gas in the second section 102 flows sequentially along the flue to the dust collector 5, the internal circulation fan 3, and is then conveyed to the mixer 6. After being cooled by heat exchange, the flue gas in the second section 102 can continue to flow through the dust collector 5 to remove dust and impurities from the flue gas; the flue gas after dust removal is then pressurized by the internal circulation fan 3 and enters the mixer 6. The dust collector 5 can be a multi-tube dust collector or a bag dust collector to be suitable for treating sintering flue gas with different temperatures and compositions.

[0028] Example 3 Based on the above embodiment, the annular cooler 2 includes five annular cooling fans, namely, annular cooling fan 1# 201, annular cooling fan 202, annular cooling fan 203, annular cooling fan 204, and annular cooling fan 205. The fume hood of annular cooling fan 205 is connected in series to the air inlet of annular cooling fan 204, and the fume hood of annular cooling fan 204 is connected in series to the air inlet of annular cooling fan 203, forming a closed-loop reuse path for the first stage of annular cooling. The fume hoods of annular cooling fans 1# 201 and 2# 202 are connected to an external waste heat boiler through pipelines to send the flue gas from the third stage of annular cooling into the external waste heat boiler to produce steam. The fume hood of annular cooling fan 203 is connected to an independent branch of the second stage of annular cooling, and the branch of the second stage of annular cooling is connected to the air mixer 6 through annular cooling induced draft fan 4.

[0029] Specifically, the annular cooler 2 can be configured with multiple annular cooling fans and corresponding goggles for each fan. In one specific arrangement, the annular cooler 2 has five annular cooling fans: fan 1#201, fan 2#202, fan 3#203, fan 4#204, and fan 5#205. The average temperature of the goggles for fan 5#205 is 70℃~90℃, for fan 4#204 it is 150℃~190℃, for fan 3#203 it is 230℃~270℃, for fan 2#202 it is 275℃~325℃, and for fan 1#201 it is 400℃~500℃. Preferably, the average temperature of the No. 5 ring cooler 205 fume hood is 80℃, the average temperature of the No. 4 ring cooler 204 fume hood is 170℃, the average temperature of the No. 3 ring cooler 203 fume hood is 250℃, the average temperature of the No. 2 ring cooler 202 fume hood is 300℃, and the average temperature of the No. 1 ring cooler 201 fume hood is 450℃. In terms of pipeline connections, the flue gas from the first stage of the annular cooling stage of the No. 5 annular fan 205 is connected in series with the No. 4 annular fan 204 via a pipeline. The flue gas from the first stage of the annular cooling stage of the No. 4 annular fan 204 is connected in series with the No. 3 annular fan 203, achieving closed-loop reuse of the first stage flue gas. The flue gas from the second stage of the annular cooling stage of the No. 3 annular fan 203 is mixed with the exhaust gas from the outlet of the annular cooling induced draft fan 4 and the sintering internal circulation fan 3 in the mixer 6. The mixed air is then returned to the material surface of the sintering machine 1 to aid combustion and sintering. The flue gas from the second stage of the annular cooling stage in the hoods of the No. 1 annular fan 201 and the No. 2 annular fan 202 is sent to the annular cooling waste heat boiler to produce steam for power generation, realizing the high-temperature waste heat resource utilization. The above process design achieves zero emissions from the annular cooling and differentiated tiered utilization of the three stages of flue gas. Based on the heat recovery concept of tiered utilization, the above annular cooling stages are spatially divided into annular cooling stage one, annular cooling stage two, and annular cooling stage three. The flue gas temperature in the first stage of the annular cooling system is relatively low, the flue gas temperature in the second stage of the annular cooling system is higher than that in the first stage, and the flue gas temperature in the third stage of the annular cooling system is relatively high.

[0030] The fume hood of the annular cooling fan located in the first stage of the annular cooling system is connected to the air inlet of the adjacent annular cooling fan via a pipeline, thereby constructing a closed-loop reuse path for the flue gas in the first stage of the annular cooling system. As a specific implementation method, the fume hood of the No. 5 annular cooling fan 205 can be connected in series with the air inlet of the No. 4 annular cooling fan 204 via a pipeline, and the fume hood of the No. 4 annular cooling fan 204 can be connected in series with the air inlet of the No. 3 annular cooling fan 203, realizing the step-by-step reverse closed-loop reuse of the flue gas in the first stage of the annular cooling system.

[0031] The annular cooling fan located in the second section of the annular cooling unit has an independent branch for the corresponding fume hood. This branch connects to the annular cooling induced draft fan 4, which draws the flue gas from the second section of the annular cooling unit into the mixer 6. Thus, the high-concentration carbon monoxide flue gas from the first section 101 of the sintering machine 1, the high-oxygen flue gas from the second section 102 after heat exchange, cooling, and dust removal, and the high-oxygen flue gas from the second section of the annular cooling unit 1 converge and mix thoroughly inside the mixer 6, forming a circulating mixed airflow.

[0032] The annular cooling fans located in the third stage of the annular cooling system have high flue gas temperatures and abundant heat resources within their corresponding fume hoods. The fume hoods of the annular cooling fans in the third stage, including #1 annular cooling fan 201 and #2 annular cooling fan 202, are connected to an external waste heat boiler via pipelines. This high-temperature flue gas is fed into the external waste heat boiler, where steam is produced to generate electricity, thus realizing the commercial utilization of high-temperature waste heat resources.

[0033] Example 4 Based on the above embodiments, the system in this embodiment is also equipped with a flow control component, such as regulating valves installed on the corresponding branch pipelines. The number and location of the valves are set according to actual needs. Specifically, the operator can adjust the flue gas diversion ratio of the first section 101 and the second section 102 entering the internal circulation system in real time based on parameters such as the actual production load of the sintering machine 1, the material layer temperature, and the oxygen content in the furnace. Under this dynamic control, the total flue gas circulation ratio of the system can be set within the range of 15% to 40% to achieve the best combustion and energy-saving effect.

[0034] In this embodiment, the flue boiler 7 is installed on the main flue of the sintering machine 1 to exchange heat with the flue gas discharged from the second section 102 to recover heat. The exhaust port of the air mixer 6 is connected to the return air duct, which delivers the mixed air to the material surface of the sintering machine 1 to provide combustion gas for the sintering process. This application eliminates the traditional independent waste heat boiler and instead uses the flue boiler 7 installed in the main flue of the sintering machine to directly recover heat from the flue gas in the tail end of the sintering machine. Since the flue boiler 7 is directly integrated into the main flue, it not only shortens the length of the flue and reduces the equipment footprint, but also reduces equipment investment and pipeline maintenance losses.

[0035] Example 5 The difference between this embodiment and embodiments 1 to 4 lies in the flexible adjustment of the execution order of each operation step. In this embodiment, the steps of selectively diverting the flue gas from sintering machine 1 and utilizing the three-stage differentiated cascade of the annular cooler 2 can also be adjusted in order without affecting each other. This embodiment does not impose a mandatory timing limit on each step. Optionally, in some embodiments, the flue gas recirculation ratio of the second stage of the annular cooler 2 can be taken as a priority step, followed by the coordinated operation of flue gas extraction from sintering machine 1.

[0036] Those skilled in the art will understand that the steps, measures, and solutions in the various operations, methods, and processes discussed in this application can be alternated, modified, combined, or deleted. Furthermore, other steps, measures, and solutions in the various operations, methods, and processes discussed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and solutions in the prior art that are similar to those disclosed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted.

[0037] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A comprehensive recovery and recycling system for sintering ring cold flue gas, characterized in that, include: Sintering machine (1), annular cooler (2) and internal circulation system; The sintering machine (1) includes at least a first section (101) and a second section (102), the flue gas outlet of the first section (101) is connected to the internal circulation system, and the flue gas outlet of the second section (102) is connected to the internal circulation system via the flue boiler (7); The annular cooler (2) includes multiple annular cooler fans. The hood of the annular cooler fan located in the first stage of the annular cooler is connected to the air inlet of the adjacent annular cooler fan to form a closed-loop flue gas recycling passage in the first stage of the annular cooler. The hood of the annular cooler fan located in the second stage of the annular cooler is connected to the internal circulation system through a pipeline. The hood of the annular cooler fan located in the third stage of the annular cooler is connected to an external waste heat boiler.

2. The sintering ring cold flue gas comprehensive recovery and recycling system according to claim 1, characterized in that, The internal circulation system includes: an internal circulation fan (3), an annular cooling induced draft fan (4), a dust collector (5), and a mixer (6). The flue gas in the first section (101) enters the mixer (6) through the internal circulation fan (3); The flue gas in the second section (102) passes through the flue boiler (7), the dust collector (5), and the internal circulation fan (3) in sequence before entering the mixer (6); The flue gas from the annular cooling fan of the second annular cooling stage enters the mixer (6) through the annular cooling induced draft fan (4). The air mixer (6) is used to mix the incoming flue gas and return the mixed air to the material surface of the sintering machine (1).

3. The sintering ring cold flue gas comprehensive recovery and recycling system according to claim 2, characterized in that, The ring cooler (2) includes five ring coolers, namely ring cooler 1 (201), ring cooler 2 (202), ring cooler 3 (203), ring cooler 4 (204) and ring cooler 5 (205). The fume hood of the No. 5 ring cooler (205) is connected in series to the air inlet of the No. 4 ring cooler (204), and the fume hood of the No. 4 ring cooler (204) is connected in series to the air inlet of the No. 3 ring cooler (203), forming a closed-loop reuse path for the first stage of the ring cooler.

4. The sintering ring cold flue gas comprehensive recovery and recycling system according to claim 3, characterized in that, The hoods of the No. 1 ring-cooled air fan (201) and the No. 2 ring-cooled air fan (202) are connected to the external waste heat boiler through pipelines to send the flue gas from the three ring-cooled sections into the external waste heat boiler to produce steam.

5. The sintering ring cold flue gas comprehensive recovery and utilization system according to claim 1, characterized in that, The first section (101) is located in the head bellows area of ​​the sintering machine (1), and the flue gas output from the head bellows area contains carbon monoxide; the second section (102) is located in the tail bellows area of ​​the sintering machine (1).

6. The sintering ring cold flue gas comprehensive recovery and recycling system according to claim 1, characterized in that, The flue boiler (7) is installed on the main flue pipe of the sintering machine (1) and is used to exchange heat with the flue gas discharged from the second section (102) to recover heat.

7. The sintering ring cold flue gas comprehensive recovery and recycling system according to claim 2, characterized in that, The exhaust port of the air mixer (6) is connected to the return air duct, and the return air duct delivers the mixed air to the material surface of the sintering machine (1) to provide combustion-supporting gas for the sintering process.

8. The sintering ring cold flue gas comprehensive recovery and recycling system according to claim 2, characterized in that, The flue gas temperature in the first section (101) is 70℃~90℃, and the flue gas temperature in the second section (102) is 350℃~450℃.

9. A comprehensive recovery and recycling system for sintering ring cold flue gas according to claim 8, characterized in that, After the flue gas in the second section (102) is cooled by heat exchange in the flue boiler (7), it flows sequentially along the flue to the dust collector (5), the internal circulation fan (3), and is then transported to the air mixer (6).

10. A comprehensive recovery and recycling system for sintering ring cold flue gas according to claim 2, characterized in that, The fume hood of the No. 3 ring-cooled fan (203) is connected to the independent ring-cooled second-stage branch, and the ring-cooled second-stage branch is connected to the air mixer (6) through the ring-cooled induced draft fan (4).

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