A sintering machine flue gas waste heat recycling device and recycling method

Abstract

The present application relates to a kind of sintering machine flue gas waste heat recycling device and recycling method, along the flue gas conveying direction, recycling device includes sintering machine, flue gas evaporator, dust removal device, flue gas conveying device and chimney connected in sequence;Sintering machine includes being arranged in the tail of sintering machine and being arranged in the chute of the lower part of pulverizing device;Sintering machine is provided with flue gas cover, and first flue gas outlet is arranged on the flue gas cover at the tail of sintering machine, and second flue gas outlet is arranged on the flue gas cover at the chute;Flue gas evaporator includes forced circulation evaporator and natural circulation evaporator;First flue gas outlet is connected with forced circulation evaporator;Second flue gas outlet is connected with natural circulation evaporator.The present application carries out heat exchange to the flue gas of different positions of sintering machine respectively, increases the waste heat recovery efficiency, and uses double operating system to carry out heat exchange, while reducing the system energy consumption in the reasonable use of plant space.

Description

Technical Field

[0001] This invention relates to the field of flue gas waste heat recovery and utilization technology, and in particular to a device and method for recovering and utilizing waste heat from sintering machine flue gas. Background Technology

[0002] Sintering is a key process in steel production, accounting for approximately 9-12% of total metallurgical energy consumption, second only to ironmaking. The average energy consumption per ton of sinter is 50-60 kg of standard coal, with the majority of this energy consumed in the form of sensible heat from waste gas (approximately 32%) and sensible heat from the sinter itself (approximately 28%). The waste heat recovery rate for this portion of sensible heat is only 30-40%. Therefore, achieving efficient recovery of sintering waste heat is of great significance for energy conservation and emission reduction in steel production.

[0003] Currently, there are two main technologies for sintering waste heat recovery: The first is the waste heat recovery technology from the sintering machine's main flue gas. This involves feeding the high-temperature flue gas (300-400℃) from the tail section of the main flue into a waste heat boiler, utilizing the sensible heat of the flue gas to produce high-quality steam for power generation or other purposes. This technology is relatively mature, but due to the intermittent and dynamic characteristics of the sintering process, the flue gas temperature fluctuates greatly, leading to unstable waste heat recovery efficiency and affecting boiler steam production. The second is the waste heat recovery technology from the annular cooler. This involves using an annular cooler fan to blow air into the annular cooler, recovering its sensible heat through heat exchange between the air and the sintered ore. The exhaust gas (300-400℃) is then fed into the waste heat boiler to generate steam for power generation or other purposes. However, the dynamic operation of the annular cooler structure (such as trolley movement) causes easy wear of the seals, and the high dust content in the exhaust gas (especially in the later stages) exacerbates equipment wear and blockage. Furthermore, the device has poor sealing (air leakage rate of 20-30%), affecting the system's waste heat recovery efficiency.

[0004] CN107131770A discloses a method for synergistic emission reduction through iron ore sintering waste heat recovery. x and NO xThe method is disclosed, along with the equipment system used in the method. This equipment system, starting from the inlet of the sintering machine, comprises, in sequence: a denitrification section flue, a desulfurization section flue, and a circulating flue. The denitrification section flue includes 60% of the total number of sintering air boxes; the desulfurization section flue includes 20% of the total number of sintering air boxes; the circulating flue includes the remaining sintering air boxes; and a crusher is located at the outlet of the sintering machine, whereby the sintered ore, after being sintered by the sintering machine, is crushed by the crusher. Afterwards, the gas falls into the vertical cooler for cooling. The denitrification section flue, electrostatic precipitator, denitrification induced draft fan, vertical cooler, gravity dust collector, denitrification device, waste heat power generation device, denitrification emission pre-dust collector, and denitrification chimney are connected in sequence. The desulfurization section flue, high-temperature dust collector, desulfurization induced draft fan, waste heat boiler, desulfurization device, desulfurization emission pre-dust collector, and desulfurization chimney are connected in sequence. The power generation device is connected to the waste heat boiler. The circulating flue is connected to the inlet of the sintering machine. The disclosed method involves passing the denitrified flue gas into the waste heat power generation device and the desulfurized flue gas through the waste heat boiler to recover waste heat from the flue gas. However, the waste heat recovery efficiency is unstable.

[0005] In summary, to address the problems of unstable steam production from waste heat boilers due to intermittent fluctuations in flue gas temperature, which affect waste heat recovery efficiency, and the issues of high inlet flue gas temperature and reduced lifespan of dust collectors in the flue gas dust removal process at the tail end of the sintering machine, it is necessary to develop a device for recovering and utilizing waste heat from sintering machine flue gas. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a device and method for recovering and utilizing waste heat from sintering machine flue gas. By subjecting flue gas from different locations in the sintering machine to different types of heat exchange treatments, the problem of unstable steam production in the waste heat boiler caused by intermittent fluctuations in flue gas temperature is solved, thereby increasing the waste heat recovery efficiency. Furthermore, the placement of each piece of equipment in the recovery and utilization device is restricted to reduce the temperature of the flue gas at the inlet of the dust removal device and increase the service life of the dust removal device.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a device for recovering and utilizing waste heat from sintering machine flue gas. Along the flue gas conveying direction, the recovery and utilization device includes a sintering machine, a flue gas evaporator, a dust removal device, a flue gas conveying device, and a chimney connected in sequence.

[0009] The sintering machine includes a crushing device disposed at the tail end of the sintering machine and a chute disposed below the crushing device.

[0010] The sintering machine is equipped with a flue gas hood, and a first flue gas outlet is provided on the flue gas hood at the tail end of the sintering machine, and a second flue gas outlet is provided on the flue gas hood at the chute.

[0011] The flue gas evaporator includes a forced circulation evaporator and a natural circulation evaporator;

[0012] The first flue gas outlet is connected to the forced circulation evaporator;

[0013] The second flue gas outlet is connected to the natural circulation evaporator.

[0014] This invention provides a first flue gas outlet and a second flue gas outlet on the flue gas hood at the tail end of the sintering machine and the flue gas hood at the sintering machine chute, respectively. Based on the location characteristics of the first and second flue gas outlets, a dual-operation system is adopted, connecting the first and second flue gas outlets to a forced circulation evaporator and a natural circulation evaporator for heat exchange, respectively. This achieves multi-heat source synergistic recovery, increases waste heat recovery efficiency, and reduces system energy consumption while making reasonable use of plant space. Furthermore, in the recycling device of this invention, the dust removal device is placed after the flue gas evaporator, which can reduce the temperature of the flue gas entering the dust removal device and extend its service life.

[0015] As a preferred embodiment of the present invention, the recycling device further includes a flue gas temperature monitoring device and a cooling device.

[0016] Preferably, the chute of the sintering machine is connected to the cooling device.

[0017] Preferably, the first flue gas outlet is located above the pulverizing device.

[0018] Preferably, the flue gas temperature monitoring device is installed on the connecting pipe between the first flue gas outlet and the forced circulation evaporator.

[0019] Preferably, the cooling device includes any one or a combination of at least two of the following: an annular cooler, a belt cooler, or a vertical cooler. Typical but non-limiting combinations include: a combination of an annular cooler and a belt cooler, a combination of an annular cooler and a vertical cooler, a combination of a belt cooler and a vertical cooler, and a combination of an annular cooler, a belt cooler, and a vertical cooler.

[0020] As a preferred technical solution of the present invention, the recycling device further includes a steam drum, a water tank, a water supply pump, and a circulating water pump.

[0021] Preferably, the forced circulation evaporator, the natural circulation evaporator, and the water tank are all connected to the steam drum.

[0022] Preferably, the steam drum is provided with a gas-liquid mixing inlet, a liquid phase inlet, a liquid phase outlet, and a gas phase outlet.

[0023] Preferably, the gas-liquid mixing inlet includes a first gas-liquid mixing inlet and a second gas-liquid mixing inlet.

[0024] Preferably, the liquid phase outlet includes a first liquid phase outlet and a second liquid phase outlet.

[0025] Preferably, the first gas-liquid mixing inlet and the first liquid phase outlet are respectively connected to the forced circulation evaporator.

[0026] Preferably, the second gas-liquid mixing inlet and the second liquid phase outlet are respectively connected to the natural circulation evaporator.

[0027] Preferably, the water tank is connected to the liquid phase inlet of the steam drum.

[0028] Preferably, the water pump is installed on the connecting pipe between the water tank and the liquid phase inlet of the steam drum.

[0029] Preferably, the circulating water pump is installed on the connecting pipe between the first liquid phase outlet of the steam drum and the forced circulation evaporator.

[0030] Preferably, the gas phase outlet of the steam drum is connected to the plant's steam pipeline network.

[0031] As a preferred technical solution of the present invention, the forced circulation evaporator includes a header, a shell, a flue gas interface, and a twisted fin tube.

[0032] In some embodiments, the flue gas inlets are respectively located on both sides of the shell, and the twisted-plate tubes are located inside the shell. The pipes of the twisted-plate tubes are connected to the header. The flue gas on the flue gas side of the forced circulation evaporator enters the shell of the forced circulation evaporator through the flue gas inlets, exchanges heat on the outside of the twisted-plate tubes, and finally exits through the flue gas outlet on the other side of the shell and enters the dust removal device. The water on the steam side of the forced circulation evaporator enters through the header. The header has the function of distributing water flow and can evenly distribute water into the twisted-plate tubes. The water flows in the twisted-plate tubes and exchanges heat with the flue gas outside the tubes, absorbing the heat of the flue gas. When the water temperature reaches saturation, part of the water vaporizes into steam, forming a gas-liquid mixture. The gas-liquid mixture is discharged through the gas-liquid mixture outlet at the top of the shell and enters the steam drum.

[0033] Preferably, the forced circulation evaporator includes at least two twisted fin tubes, for example, 2, 10, 20, 50 or 100, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0034] Preferably, the twisted tubes are arranged in a cross pattern in the forced circulation evaporator.

[0035] In this invention, the twisted fin tubes are arranged in a cross pattern in the forced circulation evaporator. The flue gas outside the twisted fin tubes flows in the tortuous channels between the tubes, which can enhance the flue gas disturbance and improve the convective heat transfer coefficient, thereby improving the heat exchange efficiency between the flue gas and the saturated water inside the twisted fin tubes.

[0036] As a preferred embodiment of the present invention, the twisted tube includes a twisted plate and a base tube.

[0037] Preferably, the twisted piece includes a first twisted piece and a second twisted piece.

[0038] Preferably, the first twisted piece and the second twisted piece are respectively disposed on both sides of the base tube.

[0039] Preferably, the first twisted piece and the second twisted piece are symmetrically distributed along the base tube.

[0040] Preferably, the twisted piece includes at least two of the first twisted pieces, for example, 2, 10, 50, 100 or 200, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0041] Preferably, the distance between the first twisted pieces is 80 to 120 mm, for example, it can be 80 mm, 90 mm, 100 mm, 110 mm or 120 mm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0042] This invention designs the structure of the twisted fins in the twisted fin tube of a forced circulation evaporator, enabling centrifugal force to be generated when flue gas passes through the twisted fin tube. This causes dust in the flue gas to be thrown outward, making it less likely for dust particles to adhere to the surface of the twisted fin tube. Under the action of vibration or wind, the dust particles are more likely to fall off, preventing dust accumulation and bridging in the twisted fin tube and causing blockage. At the same time, the flue gas can flow turbulently between the twisted fins, enhancing heat exchange efficiency and reducing the local erosion of the twisted fin tube wall by the flue gas, thus increasing the service life of the twisted fin tube.

[0043] Preferably, the forced circulation evaporator includes any one or a combination of at least two of the following: a straight-tube forced circulation evaporator, a U-tube forced circulation evaporator, or a spiral-tube forced circulation evaporator. Typical but non-limiting combinations include: a combination of a straight-tube forced circulation evaporator and a U-tube forced circulation evaporator; a combination of a straight-tube forced circulation evaporator and a spiral-tube forced circulation evaporator; a combination of a U-tube forced circulation evaporator and a spiral-tube forced circulation evaporator; and a combination of a straight-tube forced circulation evaporator, a U-tube forced circulation evaporator, and a spiral-tube forced circulation evaporator.

[0044] It is understood that the straight tube, U-tube, and spiral tube in the straight tube forced circulation evaporator, U-tube forced circulation evaporator, or spiral tube forced circulation evaporator described in this invention all refer to the tube type of the base tube.

[0045] Preferably, the natural circulation evaporator includes any one or a combination of at least two of the following: a straight tube natural circulation evaporator, a U-tube natural circulation evaporator, or a spiral tube natural circulation evaporator. Typical but non-limiting combinations include: a combination of a straight tube natural circulation evaporator and a U-tube natural circulation evaporator; a combination of a straight tube natural circulation evaporator and a spiral tube natural circulation evaporator; a combination of a U-tube natural circulation evaporator and a spiral tube natural circulation evaporator; and a combination of a straight tube natural circulation evaporator, a U-tube natural circulation evaporator, and a spiral tube natural circulation evaporator.

[0046] It is understood that the straight tube, U-tube, and spiral tube in the straight tube natural circulation evaporator, U-tube natural circulation evaporator, or spiral tube natural circulation evaporator described in this invention all refer to the tube type of the base tube.

[0047] Preferably, the dust removal device includes any one or a combination of at least two of the following: an electrostatic precipitator, a gravity dust collector, or a bag filter. Typical but non-limiting combinations include: a combination of an electrostatic precipitator and a gravity dust collector, a combination of an electrostatic precipitator and a bag filter, a combination of a gravity dust collector and a bag filter, and a combination of an electrostatic precipitator, a gravity dust collector, and a bag filter.

[0048] As a preferred technical solution of the present invention, the flue gas temperature monitoring device includes a proportional-integral-differential (PID) controller.

[0049] Preferably, the PID controller can control the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device according to the measured temperature.

[0050] This invention, by installing a flue gas temperature monitoring device in the recycling unit, can detect the temperature of the flue gas discharged from the first flue gas outlet in real time and form a feedback mechanism. When the flue gas temperature is lower than the set temperature, the motor speed of the feed water pump and the circulating water pump will be reduced, thereby reducing the feed water flow into the flue gas evaporator; and the speed of the flue gas conveying device will be reduced, thereby reducing the flue gas flow into the flue gas evaporator. This reduces the operating load of the system when the sintering flue gas temperature fluctuates, achieving a high efficiency and energy saving effect.

[0051] Preferably, when the temperature measured by the flue gas temperature monitoring device is lower than the set temperature, the valve opening of the water supply pump, the circulating water pump and the flue gas conveying device is adjusted to 20% to 40%, for example, it can be 20%, 25%, 30%, 35% or 40%, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0052] Preferably, when the temperature measured by the flue gas temperature monitoring device is comparable to the set temperature, the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device is adjusted to 70-80%, for example, 70%, 72%, 74%, 76%, 78%, or 80%, but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0053] Preferably, the set temperature is 170 to 230°C, for example, it can be 170°C, 180°C, 190°C, 200°C, 210°C, 220°C or 230°C, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0054] Secondly, the present invention provides a method for recovering and utilizing waste heat from sintering machine flue gas, wherein the recovery and utilization method employs the waste heat recovery and utilization device for sintering machine flue gas described in the first aspect.

[0055] The flue gas recovery and utilization method provided by this invention is simple and convenient, and has good application prospects in industrial flue gas waste heat recovery.

[0056] As a preferred embodiment of the present invention, the recycling method includes the following steps:

[0057] The raw sintering meal is sintered to obtain sintered clinker and flue gas. The first part of the flue gas enters the forced circulation evaporator through the first flue gas outlet of the sintering machine for forced circulation heat exchange to obtain the first heat-exchanged flue gas. The second part of the flue gas enters the natural circulation evaporator through the second flue gas outlet of the sintering machine for natural circulation heat exchange to obtain the second heat-exchanged flue gas.

[0058] The flue gas after the first heat exchange and the flue gas after the second heat exchange are discharged through the chimney after dust removal treatment.

[0059] The sintered clinker is crushed and then discharged through the chute of the sintering machine.

[0060] As a preferred technical solution of the present invention, the recycling method further includes: the sintered clinker is discharged through a chute and then cooled.

[0061] Preferably, the sintering raw materials include iron ore, limestone, and coke.

[0062] Preferably, the sintering temperature is 1000-1400℃, for example, 1000℃, 1100℃, 1200℃, 1300℃ or 1400℃, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0063] Preferably, the sintering time is 6 to 10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0064] Preferably, the temperature of the sintered clinker is 700-900℃, for example, 700℃, 750℃, 800℃, 850℃ or 900℃, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0065] Preferably, the sintered clinker is in the shape of blocks.

[0066] Preferably, the particle size of the sintered clinker after the pulverization treatment is 5 to 50 mm, for example, it can be 5 mm, 10 mm, 20 mm, 30 mm, 40 mm or 50 mm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0067] The sintered clinker of this invention contains incompletely reacted metal particles (such as Ni and Co), which can be recycled and reused. This invention pulverizes the blocky sintered clinker to achieve a particle size of 5-50 mm, which exposes the incompletely reacted metal particles, facilitating gravity separation in the chute and improving the metal recovery rate. At the same time, the sintered clinker with a particle size of 5-50 mm has a larger specific surface area, allowing for more thorough contact with the cooling medium and a more uniform cooling rate, thus avoiding localized overheating or incomplete cooling during subsequent cooling processes.

[0068] Preferably, the cooling medium for the cooling process is air.

[0069] Preferably, the temperature of the sintered clinker after the cooling treatment is 80 to 150°C, for example, 80°C, 100°C, 120°C, 140°C or 150°C, but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0070] As a preferred technical solution of the present invention, the volume ratio of the first part of flue gas to the second part of flue gas is (1 to 4):1, for example, it can be 1:1, 2:1, 3:1 or 4:1, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0071] Preferably, the temperature of the first part of the flue gas is 170 to 230°C, for example, it can be 170°C, 180°C, 190°C, 200°C, 210°C, 220°C or 230°C, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0072] Preferably, the temperature of the flue gas after the first heat exchange is 140 to 200°C, for example, it can be 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0073] Preferably, the temperature of the second part of the flue gas is 230 to 270°C, for example, it can be 230°C, 240°C, 250°C, 260°C or 270°C, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0074] Preferably, the temperature of the flue gas after the second heat exchange is 160-200°C, for example, it can be 160°C, 170°C, 180°C, 190°C or 200°C, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0075] Preferably, the dust removal process yields dust-removed flue gas and solid particles.

[0076] Preferably, the solid particles include incompletely burned coke, iron oxide from iron ore, and carbonates from limestone.

[0077] Preferably, the concentration of solid particles in the flue gas after dust removal is <15 mg / m³. 3 For example, it could be 10 mg / m³ 3 11mg / m 3 12mg / m 3 13mg / m 3 Or 14mg / m 3 However, this does not apply to all values ​​listed above; other unlisted values ​​within the range of values ​​mentioned above are also applicable.

[0078] As a preferred embodiment of the present invention, the recycling method includes the following steps:

[0079] The raw sintering material is sintered at 1000–1400℃ for 6–10 hours to obtain blocky sintered clinker and flue gas at 700–900℃. The first part of the flue gas at 170–230℃ enters a forced circulation evaporator through the first flue gas outlet of the sintering machine for forced circulation heat exchange, resulting in a first heat-exchanged flue gas at 140–200℃. The second part of the flue gas at 230–270℃ enters a natural circulation evaporator through the second flue gas outlet of the sintering machine for natural circulation heat exchange, resulting in a second heat-exchanged flue gas at 160–200℃.

[0080] The flue gas after the first heat exchange and the flue gas after the second heat exchange are mixed and then subjected to dust removal treatment before being discharged through a chimney.

[0081] The sintered clinker is crushed and then discharged through the chute of the sintering machine.

[0082] Compared with the prior art, the present invention has at least the following beneficial effects:

[0083] This invention increases waste heat recovery efficiency by separately heat-exchanging the flue gas at different locations of the sintering machine, achieving a recovery efficiency of over 40%. Furthermore, based on the characteristics of different flue gas outlet locations of the sintering machine, a dual-operation system is adopted, which reduces system energy consumption while making reasonable use of plant space. In addition, by limiting the placement of each device in the recycling unit, this invention reduces the temperature of the flue gas at the inlet of the dust removal device, enabling the dust removal device to have a service life of over 2.5 years. Attached Figure Description

[0084] Figure 1 This is a schematic diagram of the structure of the waste heat recovery and utilization device for sintering machine flue gas provided in Embodiment 1 of the present invention.

[0085] Figure 2 This is a left view of the forced circulation evaporator provided in Embodiment 1 of the present invention.

[0086] Figure 3 This is a front view of the forced circulation evaporator provided in Embodiment 1 of the present invention.

[0087] Figure 4 This is a schematic diagram of the twisted-blade tube in the forced circulation evaporator provided in Embodiment 1 of the present invention.

[0088] Figure 5 This is the present invention. Figure 4 A magnified view of the twisted tube within the dashed box.

[0089] Figure 6 This is a schematic diagram of the sintering machine flue gas waste heat recovery and utilization device provided in Comparative Example 3 of the present invention.

[0090] Figure 7 This is a schematic diagram of the sintering machine flue gas waste heat recovery and utilization device provided in Comparative Example 4 of the present invention.

[0091] Figure 8 This is a schematic diagram of the structure of the waste heat recovery device for sintering machine flue gas provided in Comparative Example 5 of the present invention.

[0092] Among them, 1-sintering machine; 101-first flue gas outlet; 102-second flue gas outlet; 2-crushing device; 3-flue gas temperature monitoring device; 4-forced circulation evaporator; 401-twisted tube; 402-flue gas interface; 403-shell; 404-header; 4011-twisted tube; 4012-base tube; 40111-first twisted tube; 40112-second twisted tube; 5-natural circulation evaporator; 6-circulating water pump 7-Steam drum; 701-First gas-liquid mixing inlet; 702-First liquid phase outlet; 703-Second gas-liquid mixing inlet; 704-Second liquid phase outlet; 705-Liquid phase inlet; 706-Gas phase outlet; 8-Feed water pump; 9-Dust removal device; 901-First bag filter; 902-Second bag filter; 10-Flue gas conveying device; 11-Chimney; 12-Water tank; 13-Cooling device; 14-Cheet. Detailed Implementation

[0093] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0094] This invention provides a device and method for recovering and utilizing waste heat from sintering machine flue gas. Along the flue gas conveying direction, the recovery and utilization device includes a sintering machine, a flue gas evaporator, a dust removal device, a flue gas conveying device, and a chimney connected in sequence.

[0095] The sintering machine includes a crushing device disposed at the tail end of the sintering machine and a chute disposed below the crushing device.

[0096] The sintering machine is equipped with a flue gas hood, and a first flue gas outlet is provided on the flue gas hood at the tail end of the sintering machine. The first flue gas outlet is located above the crushing device, and a second flue gas outlet is provided on the flue gas hood at the chute.

[0097] The flue gas evaporator includes a forced circulation evaporator and a natural circulation evaporator;

[0098] The first flue gas outlet is connected to the forced circulation evaporator;

[0099] The second flue gas outlet is connected to the natural circulation evaporator.

[0100] In some embodiments, the recycling device further includes a flue gas temperature monitoring device and a cooling device; the chute of the sintering machine is connected to the cooling device; the flue gas temperature monitoring device is installed on the connecting pipe between the first flue gas outlet and the forced circulation evaporator.

[0101] In some embodiments, the recycling device further includes a steam drum, a water tank, a feed water pump, and a circulating water pump; the forced circulation evaporator, the natural circulation evaporator, and the water tank are all connected to the steam drum.

[0102] In some embodiments, the forced circulation evaporator includes a header, a shell, a flue gas inlet, and a twisted fin tube; the twisted fin tubes in the forced circulation evaporator are arranged crosswise in the forced circulation evaporator; the twisted fin tube includes twisted fins and a base tube; the twisted fins include a first twisted fin and a second twisted fin; the first twisted fin and the second twisted fin are symmetrically distributed along both sides of the base tube.

[0103] In some embodiments, the forced circulation evaporator includes any one or a combination of at least two of a straight tube forced circulation evaporator, a U-tube forced circulation evaporator, or a spiral tube forced circulation evaporator; the natural circulation evaporator includes any one or a combination of at least two of a straight tube natural circulation evaporator, a U-tube natural circulation evaporator, or a spiral tube natural circulation evaporator; and the dust removal device includes any one or a combination of at least two of an electrostatic precipitator, a gravity dust collector, or a bag filter.

[0104] In some embodiments, the flue gas temperature monitoring device includes a PID controller; the PID controller is capable of controlling the valve openings of the feed water pump, the circulating water pump, and the flue gas conveying device according to the measured temperature; when the temperature measured by the flue gas temperature monitoring device is lower than a set temperature, the valve openings of the feed water pump, the circulating water pump, and the flue gas conveying device are adjusted to 20-40%; when the temperature measured by the flue gas temperature monitoring device is comparable to the set temperature, the valve openings of the feed water pump, the circulating water pump, and the flue gas conveying device are adjusted to 70-80%; wherein, the set temperature is 170-230°C.

[0105] This invention addresses the problem of unstable steam production in waste heat boilers caused by intermittent fluctuations in flue gas temperature by subjecting different types of heat exchange treatment to flue gas at different locations in the sintering machine. This increases waste heat recovery efficiency and limits the placement of each piece of equipment in the recovery and utilization device to reduce the temperature of the flue gas at the inlet of the dust removal device and increase the service life of the dust removal device.

[0106] The following description is based on specific examples:

[0107] Example 1

[0108] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas, such as... Figure 1As shown, along the flue gas conveying direction, the recycling device includes a sintering machine 1, a flue gas evaporator, a dust removal device 9, a flue gas conveying device 10, and a chimney 11 connected in sequence. The recycling device also includes a flue gas temperature monitoring device 3, a circulating water pump 6, a steam drum 7, a feed water pump 8, a water tank 12, and a cooling device 13. The dust removal device 9 is a bag filter, and the cooling device 13 is an annular cooler.

[0109] The sintering machine 1 includes a crushing device 2 disposed at the tail end of the sintering machine and a chute 14 disposed below the crushing device 2; the sintering machine 1 is provided with a flue gas hood, a first flue gas outlet 101 is provided on the flue gas hood at the tail end of the sintering machine, and the first flue gas outlet 101 is disposed above the crushing device 2, a second flue gas outlet 102 is provided on the flue gas hood at the chute, and the chute 14 of the sintering machine is connected to the annular cooler.

[0110] The flue gas evaporator includes a forced circulation evaporator 4 and a natural circulation evaporator 5; the first flue gas outlet 101 is connected to the forced circulation evaporator 4; the flue gas temperature monitoring device 3 is installed on the connecting pipe between the first flue gas outlet 101 and the forced circulation evaporator 4, and the second flue gas outlet 102 is connected to the natural circulation evaporator 5; the forced circulation evaporator is a straight-tube forced circulation evaporator; the natural circulation evaporator is a straight-tube natural circulation evaporator. Simultaneously, the forced circulation evaporator 4 is connected to the first gas-liquid mixing inlet 701 of the steam drum 7 and the... The first liquid phase outlet 702 is connected, and the circulating water pump 6 is installed on the connecting pipe between the first liquid phase outlet 702 of the steam drum 7 and the forced circulation evaporator 4. The natural circulation evaporator 5 is connected to the second gas-liquid mixing inlet 703 and the second liquid phase outlet 704 of the steam drum 7. The steam drum 7 also includes a liquid phase inlet 705 and a gas phase outlet 706. The liquid phase inlet 705 is connected to the water tank 12. The feed water pump 8 is installed on the connecting pipe between the water tank 12 and the liquid phase inlet 705 of the steam drum 7. The gas phase outlet 706 is connected to the steam pipeline network of the plant area.

[0111] The left and front views of the forced circulation evaporator 4 are shown below. Figure 2 and Figure 3 As shown, the forced circulation evaporator includes a header 404, a shell 403, a flue gas inlet 402, and a twisted fin tube 401; as Figure 4 As shown, the forced circulation evaporator 4 includes 50 twisted-fin tubes 401; the twisted-fin tubes 401 are arranged in a cross pattern in the forced circulation evaporator 4; each twisted-fin tube 401 includes twisted fins 4011 and base tubes 4012; as... Figure 5As shown, the twisted piece includes 100 first twisted pieces 40111 and 100 second twisted pieces 40112; the first twisted pieces 40111 and the second twisted pieces 40112 are symmetrically distributed along the base tube 4012; the distance between the first twisted pieces 40111 is 100mm.

[0112] The flue gas temperature monitoring device 3 includes a PID controller; the PID controller can control the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device according to the measured temperature; when the temperature measured by the flue gas temperature monitoring device is lower than the set temperature, the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device is adjusted to 30%; when the temperature measured by the flue gas temperature monitoring device is equal to the set temperature, the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device is adjusted to 75%; wherein, the set temperature is 200℃.

[0113] Example 2

[0114] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas. Along the flue gas conveying direction, the recovery and utilization device includes a sintering machine 1, a flue gas evaporator, a dust removal device 9, a flue gas conveying device 10, and a chimney 11 connected in sequence. The recovery and utilization device also includes a flue gas temperature monitoring device 3, a circulating water pump 6, a steam drum 7, a feed water pump 8, a water tank 12, and a cooling device 13. The dust removal device 9 is an electrostatic precipitator, and the cooling device 13 is an annular cooler.

[0115] The sintering machine 1 includes a crushing device 2 disposed at the tail end of the sintering machine and a chute 14 disposed below the crushing device 2; the sintering machine 1 is provided with a flue gas hood, a first flue gas outlet 101 is provided on the flue gas hood at the tail end of the sintering machine and the first flue gas outlet 101 is disposed above the crushing device 2, a second flue gas outlet 102 is provided on the flue gas hood at the chute, and the chute 14 of the sintering machine is connected to the annular cooler.

[0116] The flue gas evaporator includes a forced circulation evaporator 4 and a natural circulation evaporator 5; the first flue gas outlet 101 is connected to the forced circulation evaporator 4; the flue gas temperature monitoring device 3 is installed on the connecting pipe between the first flue gas outlet 101 and the forced circulation evaporator 4, and the second flue gas outlet 102 is connected to the natural circulation evaporator 5; the forced circulation evaporator is a U-tube forced circulation evaporator; the natural circulation evaporator is a U-tube natural circulation evaporator. Simultaneously, the forced circulation evaporator 4 is connected to the first gas-liquid mixing inlet 701 of the steam drum 7 and... The first liquid phase outlet 702 is connected, and the circulating water pump 6 is installed on the connecting pipe between the first liquid phase outlet 702 of the steam drum 7 and the forced circulation evaporator 4. The natural circulation evaporator 5 is connected to the second gas-liquid mixing inlet 703 and the second liquid phase outlet 704 of the steam drum 7. The steam drum 7 also includes a liquid phase inlet 705 and a gas phase outlet 706. The liquid phase inlet 705 is connected to the water tank 12. The feed water pump 8 is installed on the connecting pipe between the water tank 12 and the liquid phase inlet 705 of the steam drum 7. The gas phase outlet 706 is connected to the plant steam pipeline network.

[0117] The forced circulation evaporator 4, from the outside to the inside, includes a header 404, a shell 403, a flue gas inlet 402, and a twisted-plate tube 401. The forced circulation evaporator 4 includes 10 twisted-plate tubes 401. The twisted-plate tubes 401 are arranged crosswise in the forced circulation evaporator 4. Each twisted-plate tube 401 includes twisted plates 4011 and a base tube 4012. Each twisted plate includes 100 first twisted plates 40111 and 50 second twisted plates 40112. The first twisted plates 40111 and the second twisted plates 40112 are symmetrically distributed along the base tube 4012. The distance between the first twisted plates 40111 is 80 mm.

[0118] The flue gas temperature monitoring device 3 includes a PID controller; the PID controller can control the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device according to the measured temperature; when the temperature measured by the flue gas temperature monitoring device is lower than the set temperature, the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device is adjusted to 40%; when the temperature measured by the flue gas temperature monitoring device is equal to the set temperature, the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device is adjusted to 70%; wherein, the set temperature is 170℃.

[0119] Example 3

[0120] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas. Along the flue gas conveying direction, the recovery and utilization device includes a sintering machine 1, a flue gas evaporator, a dust removal device 9, a flue gas conveying device 10, and a chimney 11 connected in sequence. The recovery and utilization device also includes a flue gas temperature monitoring device 3, a circulating water pump 6, a steam drum 7, a feed water pump 8, a water tank 12, and a cooling device 13. The dust removal device 9 is a gravity dust collector, and the cooling device 13 is an annular cooler.

[0121] The sintering machine 1 includes a crushing device 2 disposed at the tail end of the sintering machine and a chute 14 disposed below the crushing device 2; the sintering machine 1 is provided with a flue gas hood, a first flue gas outlet 101 is provided on the flue gas hood at the tail end of the sintering machine and the first flue gas outlet 101 is disposed above the crushing device 2, a second flue gas outlet 102 is provided on the flue gas hood at the chute, and the chute 14 of the sintering machine is connected to the annular cooler.

[0122] The flue gas evaporator includes a forced circulation evaporator 4 and a natural circulation evaporator 5; the first flue gas outlet 101 is connected to the forced circulation evaporator 4; the flue gas temperature monitoring device 3 is installed on the connecting pipe between the first flue gas outlet 101 and the forced circulation evaporator 4, and the second flue gas outlet 102 is connected to the natural circulation evaporator 5; the forced circulation evaporator is a spiral tube forced circulation evaporator; the natural circulation evaporator is a spiral tube natural circulation evaporator. Simultaneously, the forced circulation evaporator 4 is connected to the first gas-liquid mixing inlet 701 of the steam drum 7 and... The first liquid phase outlet 702 is connected, and the circulating water pump 6 is installed on the connecting pipe between the first liquid phase outlet 702 of the steam drum 7 and the forced circulation evaporator 4. The natural circulation evaporator 5 is connected to the second gas-liquid mixing inlet 703 and the second liquid phase outlet 704 of the steam drum 7. The steam drum 7 also includes a liquid phase inlet 705 and a gas phase outlet 706. The liquid phase inlet 705 is connected to the water tank 12. The feed water pump 8 is installed on the connecting pipe between the water tank 12 and the liquid phase inlet 705 of the steam drum 7. The gas phase outlet 706 is connected to the plant steam pipeline network.

[0123] The forced circulation evaporator 4, from the outside to the inside, includes a header 404, a shell 403, a flue gas inlet 402, and a twisted-plate tube 401. The forced circulation evaporator 4 includes 100 twisted-plate tubes 401. The twisted-plate tubes 401 are arranged crosswise in the forced circulation evaporator 4. Each twisted-plate tube 401 includes twisted plates 4011 and a base tube 4012. Each twisted plate includes 100 first twisted plates 40111 and 200 second twisted plates 40112. The first twisted plates 40111 and the second twisted plates 40112 are symmetrically distributed along the base tube 4012. The distance between the first twisted plates 40111 is 80 mm.

[0124] The flue gas temperature monitoring device 3 includes a PID controller; the PID controller can control the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device according to the measured temperature; when the temperature measured by the flue gas temperature monitoring device is lower than the set temperature, the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device is adjusted to 20%; when the temperature measured by the flue gas temperature monitoring device is equal to the set temperature, the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device is adjusted to 80%; wherein, the set temperature is 230℃.

[0125] Example 4

[0126] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas. The only difference from Embodiment 1 is that the twisted tube in the forced circulation evaporator does not include twisted tubes, that is, the twisted tube in the forced circulation evaporator is only a base tube. All other aspects are the same as in Embodiment 1.

[0127] Example 5

[0128] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas. The only difference from Embodiment 1 is that, except that the twisted tubes are arranged in parallel in the forced circulation evaporator, everything else is the same as in Embodiment 1.

[0129] Example 6

[0130] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas. The only difference from Embodiment 1 is that the distance between the first twisted pieces is adjusted from 100mm to 50mm, while the rest is the same as Embodiment 1.

[0131] Example 7

[0132] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas. The only difference from Embodiment 1 is that the distance between the first twisted pieces is adjusted from 100mm to 150mm, while the rest is the same as Embodiment 1.

[0133] Comparative Example 1

[0134] This comparative example provides a device for recovering and utilizing waste heat from sintering machine flue gas. The only difference from Example 1 is that the natural circulation evaporator is replaced with a straight-tube forced circulation evaporator, while the rest is the same as Example 1.

[0135] Comparative Example 2

[0136] This comparative example provides a device for recovering and utilizing waste heat from sintering machine flue gas. The only difference from Example 1 is that the forced circulation evaporator is replaced with a straight-tube natural circulation evaporator, while the rest is the same as Example 1.

[0137] Comparative Example 3

[0138] This comparative example provides a device for recovering and utilizing waste heat from sintering machine flue gas. The only difference from Example 1 is that, except that along the flue gas conveying direction, the recovery and utilization device includes a sintering machine, a dust removal device, a flue gas evaporator, a flue gas conveying device, and a chimney connected in sequence, that is, the dust removal device includes a first bag filter 901 and a second bag filter 902. The first bag filter 901 is connected to the first flue gas outlet 101 and the forced circulation evaporator 4, and the second bag filter 902 is connected to the second flue gas outlet 102 and the natural circulation evaporator 5, respectively. All other aspects are the same as in Example 1.

[0139] The recycling device described in this embodiment is as follows: Figure 6 As shown.

[0140] Comparative Example 4

[0141] This comparative example provides a device for recovering and utilizing waste heat from sintering machine flue gas. The only difference between this example and Example 1 is that the sintering machine only includes a first flue gas outlet, and the recovery and utilization device does not include a natural circulation evaporator. Otherwise, they are the same as Example 1.

[0142] The recycling device described in this embodiment is as follows: Figure 7 As shown.

[0143] Comparative Example 5

[0144] This comparative example provides a device for recovering and utilizing waste heat from sintering machine flue gas. The only difference from Example 1 is that the sintering machine only includes a second flue gas outlet, and the recovery and utilization device does not include a forced circulation evaporator. The flue gas temperature monitoring device is installed on the connecting pipe between the second flue gas outlet and the natural circulation evaporator, and the set temperature of the flue gas temperature monitoring device is adjusted to 250°C. All other aspects are the same as in Example 1.

[0145] The recycling device described in this embodiment is as follows: Figure 8 As shown.

[0146] Application Example 1

[0147] This application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method uses the recovery and utilization device described in Example 1, and includes the following steps:

[0148] Raw materials including iron ore, limestone, and coke were sintered at 1300℃ for 8 hours to obtain blocky sintered clinker and flue gas at 800℃. A first portion of the flue gas at 200℃ entered a forced circulation evaporator through the first flue gas outlet of the sintering machine for forced circulation heat exchange, resulting in a first post-heat exchange flue gas at 170℃. A second portion of the flue gas at 250℃ entered a natural circulation evaporator through the second flue gas outlet of the sintering machine for natural circulation heat exchange, resulting in a second post-heat exchange flue gas at 180℃. The volume ratio of the first portion of flue gas to the second portion of flue gas was 2:1.

[0149] The flue gas after the first heat exchange and the flue gas after the second heat exchange are mixed and then subjected to dust removal treatment to obtain dust-removed flue gas and solid particles. The solid particles include incompletely burned coke, iron oxide from iron ore, and carbonates from limestone. The concentration of solid particles in the dust-removed flue gas is 10 mg / m³. 3 After dust removal, the flue gas is discharged through the chimney;

[0150] The sintered clinker is pulverized to obtain sintered clinker with a particle size of 5-50 mm. After the sintered clinker is discharged through the chute of the sintering machine, it is cooled by air to reduce the temperature of the sintered clinker to 80-150°C before storage.

[0151] Application Example 2

[0152] This application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method uses the recovery and utilization device described in Example 2, and includes the following steps:

[0153] Raw materials including iron ore, limestone, and coke were sintered at 1000℃ for 10 hours to obtain blocky sintered clinker and flue gas at 700℃. A first portion of the flue gas at 170℃ entered a forced circulation evaporator through the first flue gas outlet of the sintering machine for forced circulation heat exchange, resulting in a first post-heat exchange flue gas at 140℃. A second portion of the flue gas at 230℃ entered a natural circulation evaporator through the second flue gas outlet of the sintering machine for natural circulation heat exchange, resulting in a second post-heat exchange flue gas at 160℃. The volume ratio of the first portion of flue gas to the second portion of flue gas was 1:1.

[0154] The flue gas after the first heat exchange and the flue gas after the second heat exchange are mixed and then subjected to dust removal treatment to obtain dust-removed flue gas and solid particles. The solid particles include incompletely burned coke, iron oxide from iron ore, and carbonates from limestone. The concentration of solid particles in the dust-removed flue gas is 10 mg / m³. 3 After dust removal, the flue gas is discharged through the chimney;

[0155] The sintered clinker is pulverized to obtain sintered clinker with a particle size of 5-50 mm. After the sintered clinker is discharged through the chute of the sintering machine, it is cooled by air to reduce the temperature of the sintered clinker to 80-150°C before storage.

[0156] Application Example 3

[0157] This application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method uses the recovery and utilization device described in Example 3, and includes the following steps:

[0158] Raw materials including iron ore, limestone, and coke were sintered at 1400℃ for 6 hours to obtain blocky sintered clinker and flue gas at 900℃. A first portion of the flue gas at 230℃ entered a forced circulation evaporator through the first flue gas outlet of the sintering machine for forced circulation heat exchange, resulting in a first heat-exchanged flue gas at 200℃. A second portion of the flue gas at 270℃ entered a natural circulation evaporator through the second flue gas outlet of the sintering machine for natural circulation heat exchange, resulting in a second heat-exchanged flue gas at 200℃. The volume ratio of the first portion of flue gas to the second portion of flue gas was 4:1.

[0159] The flue gas after the first heat exchange and the flue gas after the second heat exchange are mixed and then subjected to dust removal treatment to obtain dust-removed flue gas and solid particles. The solid particles include incompletely burned coke, iron oxide from iron ore, and carbonates from limestone. The concentration of solid particles in the dust-removed flue gas is 10 mg / m³. 3 After dust removal, the flue gas is discharged through the chimney;

[0160] The sintered clinker is pulverized to obtain sintered clinker with a particle size of 5-50 mm. After the sintered clinker is discharged through the chute of the sintering machine, it is cooled by air to reduce the temperature of the sintered clinker to 80-150°C before storage.

[0161] Application Example 4

[0162] This application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method is carried out using the recovery and utilization device described in Example 4. Except that the recovery and utilization method is carried out using the recovery and utilization device provided in Example 4, and the temperature of the flue gas after the first heat exchange is 183°C, all other aspects are the same as in Application Example 1.

[0163] Application Example 5

[0164] This application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method is carried out using the recovery and utilization device described in Example 5. Except that the recovery and utilization method is carried out using the recovery and utilization device provided in Example 5, and the temperature of the flue gas after the first heat exchange is 182°C, all other aspects are the same as in Application Example 1.

[0165] Application Example 6

[0166] This application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method is carried out using the recovery and utilization device described in Example 6. Except that the recovery and utilization method is carried out using the recovery and utilization device provided in Example 6, and the temperature of the flue gas after the first heat exchange is 175°C, all other aspects are the same as in Application Example 1.

[0167] Application Example 7

[0168] This application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method is carried out using the recovery and utilization device described in Example 7. Except that the recovery and utilization method is carried out using the recovery and utilization device provided in Example 7, and the temperature of the flue gas after the first heat exchange is 177°C, all other aspects are the same as in Application Example 1.

[0169] Comparative Application Example 1

[0170] This comparative application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method is carried out using the recovery and utilization device described in Comparative Example 1. Except that the recovery and utilization method is carried out using the recovery and utilization device provided in Comparative Example 1 and the temperature of the flue gas after the second heat exchange is 190°C, all other aspects are the same as in Application Example 1.

[0171] Comparative Application Example 2

[0172] This comparative application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method is carried out using the recovery and utilization device described in Comparative Example 2. Except that the recovery and utilization method is carried out using the recovery and utilization device provided in Comparative Example 2 and the temperature of the flue gas after the first heat exchange is 180°C, all other aspects are the same as in Application Example 1.

[0173] Comparative Application Example 3

[0174] This comparative application example provides a method for recovering waste heat from sintering machine flue gas. The recovery method uses the recovery device described in Comparative Example 3, but with the following adjustments: sintering raw materials including iron ore, limestone, and coke are sintered at 1300℃ for 8 hours to obtain blocky sintered clinker and flue gas at 800℃; wherein, a first portion of the flue gas at 200℃ enters a first bag filter for dust removal through the first flue gas outlet of the sintering machine. After dust treatment, the flue gas enters a forced circulation evaporator for forced circulation heat exchange, resulting in a first heat-exchange flue gas at a temperature of 190°C. The second part of the flue gas, at a temperature of 250°C, enters a second bag filter for dust removal through the second flue gas outlet of the sintering machine, and then enters a natural circulation evaporator for natural circulation heat exchange, resulting in a second heat-exchange flue gas at a temperature of 200°C. The volume ratio of the first part of the flue gas to the second part of the flue gas is 2:1. Except for the fact that the first and second heat-exchange flue gas are mixed and discharged through a chimney, everything else is the same as in Application Example 1.

[0175] Comparative Application Example 4

[0176] This comparative application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method uses the recovery and utilization device described in Comparative Example 4. Except that the recovery and utilization method uses the recovery and utilization device provided in Comparative Example 4, the following adjustments are made: sintering raw materials including iron ore, limestone, and coke are sintered at 1300°C for 8 hours to obtain block sintered clinker at 800°C and flue gas at 200°C; the flue gas enters a forced circulation evaporator through the first flue gas outlet of the sintering machine for forced circulation heat exchange to obtain heat-exchanged flue gas at 170°C; the heat-exchanged flue gas is subjected to dust removal treatment to obtain dust-removed flue gas, which is discharged through a chimney. All other aspects are the same as in Application Example 1.

[0177] Comparative Application Example 5

[0178] This comparative application example provides a method for recovering and utilizing waste heat from sintering machine flue gas. The recovery and utilization method uses the recovery and utilization device described in the comparative example. Except that the recovery and utilization method uses the recovery and utilization device provided in comparative example 5, the following adjustments are made to the recovery and utilization method: sintering raw materials including iron ore, limestone, and coke are sintered at 1300℃ for 8 hours to obtain block sintered clinker at 800℃ and flue gas at 250℃; the flue gas enters a natural circulation evaporator through the second flue gas outlet of the sintering machine for natural circulation heat exchange to obtain heat-exchanged flue gas at 180℃; the heat-exchanged flue gas is subjected to dust removal treatment to obtain dust-removed flue gas, which is discharged through a chimney. All other aspects are the same as in application example 1.

[0179] This invention calculates the sensible heat recovery efficiency η based on the change in flue gas temperature before and after heat exchange, wherein the sensible heat recovery efficiency of the flue gas discharged from the first flue gas outlet is: The exhaust gas temperature is 120℃, and Q1 is the flue gas flow rate discharged from the first flue gas outlet, in m³ / s. 3 / h, where Q is the sum of the flue gas flow rates discharged from the first and second flue gas outlets, in meters per second (m³). 3 / h;

[0180] Similarly, the sensible heat recovery efficiency of the flue gas discharged from the second flue gas outlet is: Q2 represents the flue gas flow rate discharged from the second flue gas outlet, in meters per second (m³). 3 / h, sensible heat recovery efficiency η=η1+η2, the concentration of solid particles in the flue gas after dust removal is detected, when the concentration of solid particles in the flue gas after dust removal reaches 20mg / m³ 3 When the dust removal device needs to be replaced, its service life is determined by the time it is used. Similarly, when the sensible heat recovery efficiency of the flue gas decreases to 80% of its initial value, the twisted-plate tubes in the forced circulation evaporator need to be replaced. The service life of these twisted-plate tubes is determined by the time they are used. The estimated results based on the test data are shown in Table 1.

[0181] Table 1

[0182]

[0183] The test results show that:

[0184] (1) As can be seen from Application Examples 1 to 3, the present invention solves the problem of unstable steam production in waste heat boiler caused by intermittent fluctuations in flue gas temperature by performing different types of heat exchange treatment on flue gas at different locations of the sintering machine, increases waste heat recovery efficiency, and its sensible heat recovery efficiency can reach more than 33.74%. Furthermore, the placement of each piece of equipment in the recycling device is limited to reduce the temperature of flue gas at the inlet of the dust removal device, increase the service life of the dust removal device, and make the service life of the dust removal device reach more than 2.5 years.

[0185] (2) As can be seen from Application Examples 1 and 4-7, the present invention further optimizes the structure of the flue gas evaporator, so that the twisted fin tubes in the flue gas evaporator are arranged in a cross pattern, so that the flue gas outside the twisted fin tubes flows in the curved channel between the tubes with alternating expansion and contraction, which enhances the flue gas disturbance and improves the convective heat transfer coefficient, thereby improving the heat exchange efficiency between the flue gas and the saturated water in the twisted fin tubes. The structure of the twisted fins in the twisted fin tubes is designed so that the flue gas can generate centrifugal force when passing through the twisted fin tubes, so that the dust in the flue gas is thrown outward. The dust particles are not easy to adhere to the surface of the twisted fin tubes and are easier to fall off under the action of vibration or wind, which can prevent the dust accumulation and bridging of the twisted fin tubes and cause blockage. At the same time, the flue gas can flow turbulently between the twisted fins, which enhances the heat exchange efficiency. It reduces the local scouring of the twisted fin tube wall by the flue gas, increases the service life of the twisted fin tubes, and ultimately increases the sensible heat recovery efficiency and the service life of the dust removal device and the twisted fin tubes.

[0186] (3) As can be seen from Application Example 1 and Comparative Application Examples 1-2, the present invention performs different types of heat exchange treatment on the flue gas at different locations of the sintering machine, that is, the flue gas evaporator adopts a mode of forced circulation combined with natural circulation, which can increase the sensible heat recovery efficiency while making reasonable use of the plant space.

[0187] (4) As can be seen from Application Example 1 and Comparative Application Example 3, the present invention can reduce the temperature of the flue gas entering the dust removal device by arranging the dust removal device after the flue gas evaporator, and remove some dust particles by utilizing the special structure of the flue gas evaporator, thereby increasing the sensible heat recovery efficiency and extending the service life of the dust removal device.

[0188] (5) As can be seen from Application Example 1 and Comparative Application Examples 4-5, the present invention sets a first flue gas outlet and a second flue gas outlet at the tail end of the sintering machine and on the sintering machine chute, respectively, and connects the first flue gas outlet and the second flue gas outlet to a forced circulation evaporator and a natural circulation evaporator for heat exchange treatment, so as to realize the coordinated recovery of multiple heat sources and increase the waste heat recovery efficiency.

[0189] In summary, this invention increases waste heat recovery efficiency by separately treating the flue gas at different locations of the sintering machine, achieving a recovery efficiency of over 33.74%. Furthermore, based on the characteristics of different flue gas outlet locations in the sintering machine, a dual-operation system is adopted, reducing system energy consumption while making reasonable use of plant space. Moreover, by limiting the placement of each device in the recycling unit, this invention lowers the temperature of the flue gas at the dust removal device inlet, extending the service life of the dust removal device to over 2.5 years. Finally, the structure of the flue gas evaporator is designed to extend its service life to over 4.8 years.

[0190] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A device for recovering and utilizing waste heat from sintering machine flue gas, characterized in that, Along the flue gas conveying direction, the recycling device includes a sintering machine, a flue gas evaporator, a dust removal device, a flue gas conveying device, and a chimney connected in sequence; The sintering machine includes a crushing device disposed at the tail end of the sintering machine and a chute disposed below the crushing device. The sintering machine is equipped with a flue gas hood, and a first flue gas outlet is provided on the flue gas hood at the tail end of the sintering machine, and a second flue gas outlet is provided on the flue gas hood at the chute. The flue gas evaporator includes a forced circulation evaporator and a natural circulation evaporator; The first flue gas outlet is connected to the forced circulation evaporator; The second flue gas outlet is connected to the natural circulation evaporator; The recycling device also includes a steam drum, a water tank, a water supply pump, and a circulating water pump; The forced circulation evaporator, the natural circulation evaporator, and the water tank are all connected to the steam drum; The steam drum is equipped with a gas-liquid mixing inlet, a liquid phase inlet, a liquid phase outlet, and a gas phase outlet; The gas-liquid mixing inlet includes a first gas-liquid mixing inlet and a second gas-liquid mixing inlet; The liquid phase outlet includes a first liquid phase outlet and a second liquid phase outlet; The first gas-liquid mixing inlet and the first liquid phase outlet are respectively connected to the forced circulation evaporator; The circulating water pump is installed on the connecting pipe between the first liquid phase outlet of the steam drum and the forced circulation evaporator. The second gas-liquid mixing inlet and the second liquid phase outlet are respectively connected to the natural circulation evaporator.

2. The recycling device according to claim 1, characterized in that, The recycling device also includes a flue gas temperature monitoring device and a cooling device; The chute of the sintering machine is connected to the cooling device; The first flue gas outlet is located above the pulverizing device; The flue gas temperature monitoring device is installed on the connecting pipe between the first flue gas outlet and the forced circulation evaporator.

3. The recycling device according to claim 2, characterized in that, The water tank is connected to the liquid phase inlet of the steam drum; The water supply pump is installed on the connecting pipe between the water tank and the liquid phase inlet of the steam drum; The steam drum's gas phase outlet is connected to the plant's steam pipeline network.

4. The recycling apparatus according to any one of claims 1-3, characterized in that, The forced circulation evaporator includes a header, a shell, a flue gas inlet, and a twisted fin tube; The forced circulation evaporator includes at least two twisted-fin tubes; The twisted tubes are arranged in a cross pattern in the forced circulation evaporator.

5. The recycling device according to claim 4, characterized in that, The twisted tube includes twisted plates and a base tube; The twisted piece includes a first twisted piece and a second twisted piece; The first twisted piece and the second twisted piece are respectively disposed on both sides of the base tube; The first twisted piece and the second twisted piece are symmetrically distributed along the base tube; The twisted piece includes at least two of the first twisted pieces; The distance between the first twisted pieces is 80~120mm.

6. The recycling device according to claim 3, characterized in that, The flue gas temperature monitoring device includes a PID controller; The PID controller can control the valve opening of the water supply pump, the circulating water pump, and the flue gas conveying device based on the measured temperature.

7. A method for recovering and utilizing waste heat from sintering machine flue gas, characterized in that, The recycling method is carried out using the waste heat recovery device for sintering machine flue gas as described in any one of claims 1-6.

8. The recycling method according to claim 7, characterized in that, The recycling method includes the following steps: The raw sintering meal is sintered to obtain sintered clinker and flue gas. The first part of the flue gas enters the forced circulation evaporator through the first flue gas outlet of the sintering machine for forced circulation heat exchange to obtain the first heat-exchanged flue gas. The second part of the flue gas enters the natural circulation evaporator through the second flue gas outlet of the sintering machine for natural circulation heat exchange to obtain the second heat-exchanged flue gas. The flue gas after the first heat exchange and the flue gas after the second heat exchange are discharged through the chimney after dust removal treatment. The sintered clinker is crushed and then discharged through the chute of the sintering machine.

9. The recycling method according to claim 8, characterized in that, The recycling method further includes: the sintered clinker is cooled after being discharged through a chute; The sintering raw materials include iron ore, limestone, and coke; The sintering temperature is 1000~1400℃; The sintering process takes 6-10 hours. The temperature of the sintered clinker is 700~900℃; The temperature of the sintered clinker after the cooling treatment is 80~150℃.

10. The recycling method according to claim 8 or 9, characterized in that, The volume ratio of the first part of flue gas to the second part of flue gas is (1~4):1; The temperature of the first part of the flue gas is 170~230℃; The temperature of the flue gas after the first heat exchange is 140~200℃; The temperature of the second part of the flue gas is 230~270℃; The temperature of the flue gas after the second heat exchange is 160~200℃.

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