Multifunctional mixture preheating device and method suitable for sintering flue gas circulation process

Abstract

A multifunctional preheating device and method for sintering flue gas recirculation processes is disclosed. A flue gas distributor is electrically connected to its central control system and a transformer. The inlet of the flue gas distributor is connected to the sintering machine, and the outlet of the flue gas distributor is connected to the inlet of a low-temperature flue gas preheater. The outlet of the low-temperature flue gas preheater is connected to a heat exchanger. A flue gas inlet detection device is installed between the heat exchanger and the low-temperature flue gas preheater, and a flue gas outlet detection device is installed on the outlet of the heat exchanger. The beneficial effects of this invention are: it can divert and mix the sintering circulating flue gas; the low-temperature flue gas preheater preheats part of the flue gas to 100-150°C; then, an air supply device inputs it into the secondary-mixing granule feeding belt; and a blower forces the flue gas containing particulate matter from the bottom to exchange heat with the secondary-mixing, moisture-containing granules. This not only increases the temperature of the granules and removes some moisture, but also reduces the problem of excessively wet mixtures caused by increased water content.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy, and more specifically to a multifunctional preheating device and method for sintering flue gas recirculation processes. Background Technology

[0002] A sintering machine is a large piece of equipment used in sintering plants in the iron and steel metallurgical industry. It is primarily used for sintering different types of iron ore powder, producing sintered ore, a crucial raw material for blast furnace ironmaking. Because sintering machines generate large amounts of flue gas during operation, containing numerous large particulate matter, SO2, NOx, dioxins, CO, and other pollutants, direct discharge would lead to excessive particulate matter in the atmosphere, causing air pollution and contributing to global warming. Therefore, some sintering machines are equipped with flue gas recirculation devices that return the flue gas to the sintering material surface for repeated sintering.

[0003] Upgrading existing sintering machine flue gas treatment systems generally involves large-scale engineering projects, high investment costs, and resource waste. To address this, Chinese invention patent CN111569623A provides a sintering flue gas internal and external circulation system, including: an internal circulation device, an external circulation device, and a desulfurization and denitrification device. The internal circulation device is connected to the front section of the main flue of the sintering machine to obtain a first purified flue gas, which is then circulated back into the sintering machine. The external circulation device is connected to the head flue and the rear section of the main flue of the sintering machine to obtain a second purified flue gas. A portion of the second purified flue gas is circulated back into the sintering machine, and the other portion enters the desulfurization and denitrification device. The flue gas from the rear section and the flue gas from the front section exchange heat before entering the external circulation device. This solution improves the waste heat utilization rate of the flue gas treatment system to a certain extent and reduces investment and operating costs.

[0004] However, in existing patented technologies, the flue gas generated in sintering machines contains a large amount of large solid particles. Industrial solid particles are a major threat to human health and a primary cause of various diseases. Directly releasing flue gas containing solid particles into the atmosphere will lead to an excessive amount of solid particles in the atmosphere, causing air pollution and contributing to problems such as rising global temperatures.

[0005] In view of this, there is an urgent need for a new type of device to improve the existing sintering flue gas recirculation system, utilizing a small amount of waste heat from the flue gas while reducing the particulate matter content of the flue gas discharged from the sintering machine, thus avoiding the environmental impact of the discharged flue gas. Therefore, a multifunctional mixed material preheating device suitable for sintering flue gas recirculation process is invented. While reducing the particulate matter content of the flue gas, it recovers and utilizes the waste heat of the flue gas for quasi-particle preheating, which is of great significance for improving the permeability of the sintering material layer, improving the fuel combustion environment, and reducing air pollution. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings and defects of existing technologies by providing a multifunctional preheating device and method for sintering flue gas recirculation processes. This device can divert and mix the sintering circulating flue gas, preheating a portion of the flue gas to 100-150°C using a low-temperature flue gas preheater. Subsequently, it is fed into the secondary-mixing pre-mixed particle distribution belt using an air supply device. A blower then forces the flue gas containing particles to exchange heat with the secondary-mixed, moisture-containing pre-mixed particles from the bottom. This not only increases the temperature of the pre-mixed particles and removes some moisture, but also reduces the problems caused by increased water content. This system addresses the issue of excessively wet mixed materials. Simultaneously, particulate matter in the flue gas can be largely adsorbed by moisture-containing quasi-particles, which then re-enter the sintering process to form ore, effectively improving the recycling rate of particulate matter. Furthermore, the central control system collects and analyzes various monitoring data from the unit, and uses the flue gas preheater and diverting exhaust air volume to control the temperature and humidity of the quasi-particle material in real time. This effectively reduces the problem of poor permeability of the sintering bed caused by excessive moisture, which is of great significance for improving the permeability of the sintering bed, improving the fuel combustion environment, and reducing the consumption of solid fuel in sintering.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a multifunctional mixed material preheating device and method suitable for sintering flue gas circulation process, comprising a heat exchange device 1, a low-temperature flue gas preheater 2, a flue gas distributor 3, a central control system 4, a transformer 5, a flue gas inlet detection device 6, a mixed material inlet detection device 7, a flue gas outlet detection device 8, and a mixed material outlet detection device 9. The flue gas distributor 3 is electrically connected to its central control system 4 and the transformer 5, and the inlet of the flue gas distributor 3 is connected to its sintering machine, while the outlet of the flue gas distributor 3 is connected to the low-temperature... The inlet of the flue gas preheater 2 is connected to the outlet of the low-temperature flue gas preheater 2, which is connected to the heat exchange device 1. A flue gas inlet detection device 6 is provided between the heat exchange device 1 and the low-temperature flue gas preheater 2. A flue gas outlet detection device 8 is installed on the outlet of the heat exchange device 1. A mixture outlet detection device 9 and a mixture inlet detection device 7 are respectively installed at the mixture inlet and outlet of the heat exchange device 1. The flue gas inlet detection device 6, the mixture inlet detection device 7, the flue gas outlet detection device 8, and the mixture outlet detection device 9 are all electrically connected to its central control system 4.

[0008] Furthermore, the main body of the low-temperature flue gas preheater 2 is made of 304 stainless steel, and the low-temperature flue gas preheater 2 is a honeycomb preheater.

[0009] Furthermore, the top of the heat exchange device 1 is equipped with an exhaust fan to ensure that the circulating flue gas is not discharged from the heat exchange device 1.

[0010] Furthermore, both the mixture inlet detection device 7 and the mixture outlet detection device 9 are equipped with a temperature detection device for detecting the temperature of the mixture and a moisture detection device for detecting the moisture content of the mixture.

[0011] Furthermore, both the flue gas inlet detection device 6 and the flue gas outlet detection device 8 are equipped with a gas temperature detection device for detecting the flue gas temperature and a gas humidity detection device for detecting the gas humidity.

[0012] Furthermore, the central control system 4 is electrically connected to its transformer 5.

[0013] A multifunctional preheating device and method for sintering flue gas recirculation process includes the following steps: collecting and mixing the flue gas from the ignition section and the non-waste heat recovery air box of the sintering machine, and then diverting it into the flue gas distributor 3; the flue gas distributor 3 diverts 20%-30% of the mixed flue gas to the low-temperature flue gas preheater 2, while the remaining flue gas re-enters the flue gas recirculation system through the flue; the low-temperature flue gas preheater 2 preheats the flue gas to 100-150℃, and then the gas is fed into the secondary mixed granule feeding belt using an air supply device; the flue gas containing particulate matter is heat-exchanged from the bottom with the secondary mixed moisture-containing granules by an exhaust fan; the secondary mixed low-temperature, high-moisture sintering granules are then fed according to the sintering machine feeding requirements. A 50-100mm thick material layer is piled up and fed into heat exchanger 1 via conveyor belt to exchange heat with high-temperature flue gas, raising the temperature of the quasi-granules and removing some moisture. After heat exchange, the quasi-granules are sent to the sintering trolley for sintering and material distribution. The gas temperature and humidity detectors on the flue gas inlet detection device 6 and the flue gas outlet detection device 8, as well as the temperature and moisture detectors on the mixture inlet detection device 7 and the mixture outlet detection device 9, transmit data in real time to the central control system 4. The central control system 4 can autonomously regulate the entire heat exchange process by adjusting the exhaust air volume of the low-temperature flue gas preheater 2 and the flue gas distributor 3 through the transformer 5, thereby adapting to different operator needs.

[0014] Furthermore, in order to ensure that the sintered mixed particles do not pulverize during the dehydration process, the granulation process requires the use of highly active lime flux to ensure that the particles have a good depulverization rate. If necessary, organic binders such as glutinous rice flour can be used for mixing and granulation.

[0015] After adopting the above technical solution, the beneficial effects of the present invention are as follows: it has at least the following advantages:

[0016] 1. It can divert and mix the sintering circulating flue gas. A low-temperature flue gas preheater is used to preheat part of the flue gas to 100-150℃. Then, the air supply device is used to input it into the secondary mixing granule feeding belt. The exhaust fan uses the flue gas containing particulate matter to exchange heat with the moisture-containing granules after secondary mixing from the bottom. This can not only increase the temperature of the granules and remove some moisture, but also reduce the problem of excessively wet mixture caused by increased water supply.

[0017] 2. At the same time, particulate matter in flue gas can be largely adsorbed by water-containing quasi-particles, which can then re-enter the sintering process to be sintered into ore, effectively improving the recycling rate of particulate matter.

[0018] 3. The central control system collects and analyzes various detection data of the unit, and controls the temperature and humidity of the granular material in real time through the flue gas preheater and the diversion exhaust air volume. This effectively reduces the problem of poor permeability of the material layer caused by excessive moisture. It is of great significance for improving the permeability of the sintering material layer, improving the fuel combustion environment, and reducing the consumption of sintering solid fuel. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the present invention.

[0021] Figure 2 This is a flowchart illustrating the present invention.

[0022] Explanation of reference numerals in the attached drawings: 1. Heat exchange device; 2. Low-temperature flue gas preheater; 3. Flue gas distributor; 4. Central control system; 5. Transformer; 6. Flue gas inlet detection device; 7. Mixed material inlet detection device; 8. Flue gas outlet detection device; 9. Mixed material outlet detection device. Detailed Implementation

[0023] See Figures 1-2As shown, the technical solution adopted in this specific embodiment is as follows: it includes a heat exchange device 1, a low-temperature flue gas preheater 2, a flue gas distributor 3, a central control system 4, a transformer 5, a flue gas inlet detection device 6, a mixed material inlet detection device 7, a flue gas outlet detection device 8, and a mixed material outlet detection device 9. The flue gas distributor 3 is electrically connected to its central control system 4 and the transformer 5, and the inlet of the flue gas distributor 3 is connected to its sintering machine. The outlet of the flue gas distributor 3 is connected to the inlet of the low-temperature flue gas preheater 2. The outlet of the low-temperature flue gas preheater 2 is connected to the heat exchange device 1. A flue gas inlet detection device 6 is provided between the heat exchange device 1 and the low-temperature flue gas preheater 2. A flue gas outlet detection device 8 is installed on the outlet of the heat exchange device 1. A mixture outlet detection device 9 and a mixture inlet detection device 7 are respectively installed at the mixture inlet and outlet of the heat exchange device 1. The flue gas inlet detection device 6, the mixture inlet detection device 7, the flue gas outlet detection device 8 and the mixture outlet detection device 9 are all electrically connected to its central control system 4.

[0024] More specifically, the main body of the low-temperature flue gas preheater 2 is made of 304 stainless steel, and the low-temperature flue gas preheater 2 is a honeycomb preheater. The use of 304 stainless steel can reduce the corrosion of the device by high-temperature water-containing flue gas, and the honeycomb preheater can preheat the flue gas by heating the heat sink through electric auxiliary heating.

[0025] More specifically, the top of the heat exchange device 1 is equipped with an exhaust fan to ensure that the circulating flue gas is not discharged from the heat exchange device 1.

[0026] More specifically, both the mixture inlet detection device 7 and the mixture outlet detection device 9 are equipped with a temperature detection device for detecting the temperature of the mixture and a moisture detection device for detecting the moisture content of the mixture. Through the temperature detection device and the moisture detection device, the temperature and moisture content of the mixture at the inlet and outlet of the heat exchange device 1 can be detected in real time, and the detected data can be transmitted to the central control system 4.

[0027] More specifically, both the flue gas inlet detection device 6 and the flue gas outlet detection device 8 are equipped with a gas temperature detection device for detecting flue gas temperature and a gas humidity detection device for detecting gas humidity. Through the gas temperature detection device and the gas humidity detection device, the temperature and humidity of the flue gas at the gas inlet and outlet of the heat exchange device 1 can be detected in real time, and the detected data can be transmitted to the central control system 4.

[0028] More specifically, the central control system 4 is electrically connected to its transformer 5. The central control system 4 can monitor relevant data on materials and flue gas at the equipment inlet and outlet in real time, and can adjust the operating voltage of the low-temperature flue gas preheater 2 and the flue gas distributor 3 through the transformer 5, automatically adjusting various data.

[0029] A multifunctional preheating device and method for sintering flue gas recirculation processes, comprising the following steps:

[0030] S1, collect and mix the flue gas from the ignition section and the non-waste heat recovery box of the sintering machine, and then divert it into the flue gas distributor 3.

[0031] S2, the flue gas diverter 3 diverts 20%-30% of the mixed flue gas to the low-temperature flue gas preheater 2, and the remaining flue gas re-enters the flue gas circulation system through the flue.

[0032] S3, the flue gas is preheated to 100-150℃ using the low temperature flue gas preheater 2, and then fed into the two-mixed standard particle cloth belt using the air supply device. The flue gas with particulate matter is heat exchanged with the water-containing standard particles after two mixing by the exhaust fan from the bottom.

[0033] S4, the low-temperature, high-moisture sintering granules after the second mixing are piled up in a 50-100mm thick layer according to the sintering machine's material feeding requirements. They are then conveyed into the heat exchange device 1 via a conveyor belt to exchange heat with the high-temperature flue gas, thereby increasing the temperature of the granules and removing some moisture. The granules after heat exchange are then sent to the sintering trolley for sintering and material feeding operations.

[0034] S5, the gas temperature and humidity detection devices on the flue gas inlet detection device 6 and the flue gas outlet detection device 8, and the temperature and moisture detection devices on the mixture inlet detection device 7 and the mixture outlet detection device 9 transmit data in real time to the central control system 4. The central control system 4 can autonomously regulate the entire heat exchange process by adjusting the exhaust air volume of the low-temperature flue gas preheater 2 and the flue gas distributor 3 through the transformer 5, thereby adapting to different needs of the operator.

[0035] To be more specific, in order to prevent pulverization during the dehydration process of sintered mixed granules, highly active lime flux is required during granulation to ensure that the granules have a good depulverization rate. If necessary, organic binders such as glutinous rice flour can be used for mixing and granulation.

[0036] The following is the relevant data for this embodiment:

[0037] In this embodiment, the sintering mixture is prepared based on the existing on-site ore blending scheme. During the ore blending process, limestone flux (A), high-activity lime flux (B), and high-activity lime flux combined with glutinous rice flour organic binder (C) are used respectively. After stacking into a 70mm quasi-granular material layer according to the above steps, a heat exchange experiment is conducted. The initial average particle size and material temperature of the two mixed quasi-granules are shown in Table 1.

[0038]

[0039] Table 1 Initial data of the two mixing particles

[0040] In this embodiment, the sintering flue gas is selected from the flue gas of the sintering machine's 15#-18# wind boxes. After being mixed, it is distributed into the heat exchanger. The flue gas detection results are shown in Table 2.

[0041]

[0042] Table 2. Detection data of circulating flue gas from the sintering machine at the inlet of the unit.

[0043] 1. Experimental Procedure

[0044] The flue gas from the ignition section and the non-waste heat recovery air box of the sintering machine is collected and mixed, and then fed into the flue gas distributor of this equipment for diversion. 25% of the mixed flue gas is diverted to the low-temperature flue gas preheater, and the remaining flue gas is re-entered into the flue gas circulation system through the flue. The flue gas is preheated to 125°C by the low-temperature flue gas preheater, and then fed into the secondary mixed granule feeding belt by the air supply device. The flue gas containing particulate matter is heat-exchanged from the bottom with the secondary mixed granules containing moisture by the exhaust fan. After the heat exchange, the flue gas is detected by the flue gas outlet detection device. The secondary mixed low-temperature, high-moisture sintering granules are stacked into a 70mm thick layer according to the sintering machine feeding requirements. They are then fed into the heat exchange device by the conveyor belt to exchange heat with the high-temperature flue gas, which increases the temperature of the granules and removes some moisture. After the heat exchange, the temperature and moisture content of the mixed material are detected by the mixed material outlet temperature and moisture detection device. Samples are taken for particle size analysis to determine the average particle size.

[0045] 2. Experimental Results and Analysis

[0046] Based on the dimensions of the sintering machine, the dew point temperature was calculated to be 62℃. This means that once the material temperature is raised above 62℃, moisture will not condense in the lower material layer, effectively eliminating the problem of poor permeability caused by excessive moisture in the material layer. The results of the measurement of the outlet data for the two types of semi-granules after heat exchange are shown in Table 3. The material temperature of all three types of semi-granules was raised to a dew point temperature above 62℃, meeting production requirements. However, the moisture content decreased from 8.20% to 6.70%. Due to the different types of flux used in the three types of semi-granules, the average particle size of the semi-granules after dehydration varies to some extent.

[0047] The flux used for quasi-particle A is limestone. The particles are mainly bonded by water. After passing through the heat exchange device, the quasi-particles lose 1.50% of water, the bonding strength between particles decreases, and the average particle size decreases from 2.73 mm to 2.12 mm.

[0048] Quasi-particles B use highly active lime as the flux. The bonding between particles is achieved through water and Ca(OH)2 colloid. After the quasi-particles lose water, they still have a certain bonding strength between particles, and the average particle size is reduced from 3.15 mm to 3.07 mm.

[0049] The flux used for quasi-particle B is highly active lime, which is combined with glutinous rice flour organic binder. After the quasi-particles lose water, they still have a certain bonding strength between particles. The average particle size is reduced from 3.33 mm to 3.29 mm, which has almost no effect on the particle size composition of the quasi-particles.

[0050]

[0051] Table 3. Export data for mixed standard particles

[0052] After heat exchange, the sintering circulating flue gas returns to the sintering circulating flue from the upper outlet for sintering flue gas circulation. Table 4 shows the flue gas data from the heat exchanger outlet and the total circulating flue gas data after mixing in the returning flue. After heat exchange, the sintering flue gas temperature decreases from 120℃ to 92℃, and the flue gas humidity increases from 34.7% to 75.4%, indicating successful heat exchange and removal of some moisture from the quasi-particles. Simultaneously, the particulate matter content decreases from 275 mg·Nm⁻³ to 7 mg·Nm⁻³, indicating that a large amount of particulate matter in the flue gas is adsorbed into the quasi-particles and re-follows them in the sintering process. After the outlet flue gas returns to the sintering circulating flue, the total circulating flue gas temperature decreases from 120℃ to 115℃, the flue gas humidity increases from 34.7% to 61.2%, and the particulate matter content decreases from 275 mg·Nm⁻³ to 145 mg·Nm⁻³.

[0053]

[0054] Table 4. Detection data of circulating flue gas from the sintering machine at the unit outlet.

[0055] Heat exchange experiments were conducted on the sintering circulating flue gas and the semi-granular mixture using this device and method. The experimental results show that this device and method can effectively increase the temperature of the mixture to above the dew point temperature without affecting the particle size of the semi-granular mixture, eliminate the influence of the excessively wet material layer, reduce the content of solid particles in the sintering circulating flue gas, increase the humidity of the flue gas, and improve the combustion environment of the fuel after the circulating flue gas returns to the sintering surface. However, the experiment shows that before using this device, it is necessary to adjust the type of flux in the sintering mixture and increase the amount of highly active lime flux to replace the binding effect of water in the mixture.

[0056] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A multifunctional preheating device for mixed materials suitable for sintering flue gas recirculation processes, characterized in that: It includes a heat exchange device (1), a low-temperature flue gas preheater (2), a flue gas distributor (3), a central control system (4), a transformer (5), a flue gas inlet detection device (6), a mixture inlet detection device (7), a flue gas outlet detection device (8), and a mixture outlet detection device (9). The flue gas distributor (3) is electrically connected to the central control system (4) and the transformer (5), and the inlet of the flue gas distributor (3) is connected to the sintering machine. The outlet of the flue gas distributor (3) is connected to the inlet of the low-temperature flue gas preheater (2). The outlet of the heat exchanger is connected to the heat exchanger (1). A flue gas inlet detection device (6) is provided between the heat exchanger (1) and the low-temperature flue gas preheater (2). A flue gas outlet detection device (8) is installed on the outlet of the heat exchanger (1). A mixture outlet detection device (9) and a mixture inlet detection device (7) are respectively installed at the mixture inlet and outlet of the heat exchanger (1). The flue gas inlet detection device (6), the mixture inlet detection device (7), the flue gas outlet detection device (8) and the mixture outlet detection device (9) are all electrically connected to the central control system (4).

2. The multifunctional mixed preheating device for sintering flue gas recirculation process according to claim 1, characterized in that: The main body of the low-temperature flue gas preheater (2) is made of 304 stainless steel, and the low-temperature flue gas preheater (2) is a honeycomb preheater.

3. The multifunctional mixed preheating device for sintering flue gas recirculation process according to claim 1, characterized in that: The top of the heat exchange device (1) is equipped with an exhaust fan to ensure that the circulating flue gas is not discharged from the heat exchange device (1).

4. The multifunctional mixed preheating device for sintering flue gas recirculation process according to claim 1, characterized in that: Both the mixture inlet detection device (7) and the mixture outlet detection device (9) are equipped with a temperature detection device for detecting the temperature of the mixture and a moisture detection device for detecting the moisture content of the mixture.

5. The multifunctional mixed preheating device for sintering flue gas recirculation process according to claim 1, characterized in that: Both the flue gas inlet detection device (6) and the flue gas outlet detection device (8) are equipped with a gas temperature detection device for detecting the flue gas temperature and a gas humidity detection device for detecting the gas humidity.

6. The multifunctional mixed preheating device for sintering flue gas recirculation process according to claim 1, characterized in that: The central control system (4) is electrically connected to the transformer (5).

7. A method for a multifunctional preheating device for sintering flue gas recirculation processes, comprising the following steps: S1, collect and mix the flue gas from the ignition section and the non-waste heat recovery box of the sintering machine, and then divert it into the flue gas distributor (3). S2, the flue gas diverter (3) diverts 20%-30% of the mixed flue gas to the low-temperature flue gas preheater (2), and the remaining flue gas re-enters the flue gas circulation system along the flue. S3, the flue gas is preheated to 100-150°C using a low-temperature flue gas preheater (2), and then fed into the two-mixed standard particle cloth belt using an air supply device. The flue gas with particulate matter is then heat-exchanged with the water-containing standard particles after two-mixing by an exhaust fan. S4, the low-temperature, high-moisture sintering quasi-granules after the second mixing are piled up in a 50-100mm thick layer based on the sintering machine's material feeding requirements. They are then conveyed into the heat exchange device (1) via a conveyor belt to exchange heat with the high-temperature flue gas, thereby increasing the temperature of the quasi-granules and removing some moisture. The quasi-granules after heat exchange are then sent to the sintering trolley for sintering and material feeding operations. S5, the gas temperature detection device and gas humidity detection device on the flue gas inlet detection device (6) and the flue gas outlet detection device (8), as well as the temperature detection device and moisture detection device on the mixture inlet detection device (7) and the mixture outlet detection device (9), transmit the detection data to the central control system (4) in real time. The central control system (4) can adjust the exhaust air volume of the low temperature flue gas preheater (2) and the flue gas distributor (3) through the transformer (5) to autonomously control the entire heat exchange process, thereby adapting to different needs of the operator.

8. The method for a multifunctional mixed preheating device suitable for sintering flue gas recirculation process according to claim 7, characterized in that: To prevent pulverization during the dehydration process of sintered mixed granules, highly active lime flux is required during granulation.

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