Recycling device and recycling method for flue gas waste heat of sintering machine

Abstract

The invention relates to a recycling device and method for flue gas waste heat of a sintering machine, and the recycling device comprises the sintering machine, a flue gas evaporator, a dust removal device, a flue gas conveying device and a chimney which are connected in sequence in the flue gas conveying direction; the sintering machine comprises a crushing device arranged at the tail part of the sintering machine and a chute arranged at the lower part of the crushing device; a flue gas cover is arranged on the sintering machine, a first flue gas outlet is formed in the flue gas cover at the tail part of the sintering machine, and a second flue gas outlet is formed in the flue gas cover at the chute; the flue gas evaporator comprises a forced circulation evaporator and a natural circulation evaporator; the first flue gas outlet is connected with the forced circulation evaporator; and the second flue gas outlet is connected with the natural circulation evaporator. Flue gas at different positions of the sintering machine is subjected to heat exchange, the waste heat recovery efficiency is improved, double operation systems are adopted for heat exchange, and the system energy consumption is reduced while the factory space is reasonably utilized.

Description

Technical Field

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

[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 ore produced by sintering is 50-60 kg of standard coal, with the majority of this energy being sensible heat from exhaust gases (approximately 32%) and sensible heat from sintered ore (approximately 28%). The waste heat recovery rate for this sensible heat is only 30-40%. Therefore, efficient recovery of sintering waste heat is crucial for energy conservation and consumption reduction in steel production.

[0003] Currently, there are two main sintering waste heat recovery technologies: the first is the flue gas waste heat recovery technology from the sintering machine flue. This technology passes the high-temperature flue gas (300-400°C) at the tail end of the flue into a waste heat boiler, where the sensible heat of the flue gas is used 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, resulting in unstable waste heat recovery efficiency and affecting boiler steam production. The second is the flue gas waste heat recovery technology from annular coolers. This technology uses an annular cooler 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°C) is then passed into a waste heat boiler to generate steam for power generation or other purposes. However, the dynamic operation of the annular cooler structure (such as the movement of the trolley) causes seals to wear easily, and the high dust content in the exhaust gas (especially the exhaust gas in the rear section) exacerbates equipment wear and blockage. At the same time, the device has poor sealing (air leakage rate of 20-30%), which affects the waste heat recovery efficiency of the system.

[0004] CN107131770A discloses a method for recovering waste heat from iron ore sintering to reduce SO2 emissions x and NO xThe invention discloses a method and an equipment system used in the method, which starts from the inlet of the sintering machine and is sequentially composed of: a denitrification section flue, a desulfurization section flue, and a circulating flue gas section flue; the denitrification section flue includes sintering bellows accounting for 60% of the total number; the desulfurization section flue includes sintering bellows accounting for 20% of the total number; the circulating flue gas section flue includes the remaining sintering bellows; the crusher is arranged at the outlet of the sintering machine, and the sintered ore is crushed by the crusher after being sintered by the sintering machine. After falling into the vertical cooler for cooling; the denitrification flue, electrostatic precipitator, denitrification induced draft fan, vertical cooler, gravity dust collector, denitrification device, waste heat power generation device, denitrification pre-emission dust collector, and denitrification chimney are sequentially connected; the desulfurization flue, high-temperature dust collector, desulfurization induced draft fan, waste heat boiler, desulfurization device, desulfurization pre-emission dust collector, and desulfurization chimney are sequentially connected; the power generation device is connected to the waste heat boiler; and the circulating flue gas section flue is connected to the inlet of the sintering machine. The disclosed method is to pass the denitrified flue gas into the waste heat power generation device and pass the desulfurized flue gas through the waste heat boiler to recover the flue gas waste heat, but the waste heat recovery efficiency is unstable.

[0005] In summary, in order to solve the problem that intermittent fluctuations in flue gas temperature lead to unstable steam production in the waste heat boiler, affecting the waste heat recovery efficiency, and the problem that the inlet flue gas temperature of the dust collector in the flue gas dust removal process at the end of the sintering machine is high and shortens the life of the dust collector, it is necessary to develop a device for recovering and utilizing the waste heat of the flue gas from the sintering machine. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a device and method for recovering and utilizing the waste heat of sintering machine flue gas. By performing different types of heat exchange treatment on the flue gas at different positions of the sintering machine, the problem of unstable steam production of the waste heat boiler caused by intermittent fluctuations in the flue gas temperature is solved, the waste heat recovery efficiency is increased, and the placement position of each device in the recovery and utilization device is limited 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 object, the present invention adopts the following technical solutions:

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

[0009] The sintering machine includes a crushing device arranged at the tail of the sintering machine, and a chute arranged below the crushing device;

[0010] The sintering machine is provided with a fume hood, a first fume outlet is provided on the fume hood at the tail of the sintering machine, and a second fume outlet is provided on the fume 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] The present 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 chute of the sintering machine, respectively. According to the position characteristics of the first flue gas outlet and the second flue gas outlet of the sintering machine, a dual operation system is adopted, and the first flue gas outlet and the second flue gas outlet are respectively connected to the forced circulation evaporator and the natural circulation evaporator for heat exchange treatment, so as to realize the coordinated recovery of multiple heat sources, increase the waste heat recovery efficiency, and reduce the system energy consumption while reasonably utilizing the plant space. Furthermore, in the recycling device of the present invention, the dust removal device is arranged after the flue gas evaporator, which can reduce the temperature of the flue gas entering the dust removal device and extend the service life of the dust removal device.

[0015] As a preferred technical solution of the present invention, the recycling device also 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 smoke outlet is arranged above the pulverizing device.

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

[0019] Preferably, the cooling device comprises any one or a combination of at least two of a ring cooler, a belt cooler or a vertical cooler, wherein typical but non-limiting combinations include: a combination of a ring cooler and a belt cooler, a combination of a ring cooler and a vertical cooler, a combination of a belt cooler and a vertical cooler, and a combination of a ring cooler, a belt cooler and a vertical cooler.

[0020] As a preferred technical solution of the present invention, the recycling device also includes a steam drum, a water tank, a feed water 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 mixed inlet includes a first gas-liquid mixed inlet and a second gas-liquid mixed 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 mixed inlet and the first liquid phase outlet are respectively connected to the forced circulation evaporator.

[0026] Preferably, the second gas-liquid mixed 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 feed pump is provided on a connecting pipe between the water tank and the liquid phase inlet of the steam drum.

[0029] Preferably, the circulating water pump is provided on a 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 steam 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 tube.

[0032] In some embodiments, the flue gas interfaces in the present invention are respectively arranged on both sides of the shell, the twisted vane tube is arranged in the shell, the pipeline of the twisted vane tube is connected to the collecting box, the flue gas on the flue gas side of the forced circulation evaporator enters the shell of the forced circulation evaporator from the flue gas interface, exchanges heat on the outside of the twisted vane tube, and is finally discharged 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 from the collecting box, and the collecting box has the function of distributing water flow, and can evenly distribute the water to the twisted vane tube. The water flows in the twisted vane tube and exchanges heat with the flue gas outside the tube, absorbing the heat of the flue gas. When the water temperature reaches saturation, part of the water vaporizes into steam to form a gas-liquid mixture, which is discharged through the gas-liquid mixing outlet at the top of the shell and enters the steam drum.

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

[0034] Preferably, the twisted-plate tubes are arranged crosswise in the forced circulation evaporator.

[0035] In the present invention, the twisted-fin tubes are cross-arranged in the forced circulation evaporator, and the flue gas outside the twisted-fin tubes flows in the curved channels that alternately expand and contract between the tubes, which can enhance the flue gas disturbance and improve the convection heat transfer coefficient, thereby improving the heat exchange efficiency between the flue gas and the saturated water in the twisted-fin tubes.

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

[0037] Preferably, the twisting plate includes a first twisting plate and a second twisting plate.

[0038] Preferably, the first twisting plate and the second twisting plate are respectively arranged on both sides of the base tube.

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

[0040] Preferably, the twisting plate includes at least two of the first twisting plates, for example, 2, 10, 50, 100 or 200, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0041] Preferably, the distance between the first twisting plates is 80 to 120 mm, for example, 80 mm, 90 mm, 100 mm, 110 mm or 120 mm, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0042] The present invention designs the structure of the twisted vanes in the twisted vane tubes in the forced circulation evaporator so that centrifugal force can be generated when the flue gas passes through the twisted vane tubes, so that dust in the flue gas is thrown out. Dust particles are not easy to adhere to the surface of the twisted vane tubes and are more likely to fall off under the action of vibration or wind, which can prevent the twisted vane tubes from accumulating dust and bridging, causing blockage. At the same time, the flue gas can flow turbulently between the twisted vanes, thereby enhancing the heat exchange efficiency; reducing the local scouring of the twisted vane tube wall by the flue gas, and increasing the service life of the twisted vane tubes.

[0043] Preferably, 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, wherein 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 can be understood that the straight tube, U-shaped tube and spiral tube in the straight tube forced circulation evaporator, U-shaped tube forced circulation evaporator or spiral tube forced circulation evaporator described in the present 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 a straight tube natural circulation evaporator, a U-tube natural circulation evaporator or a spiral tube natural circulation evaporator, wherein 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 can be understood that the straight tube, U-shaped tube and spiral tube in the straight tube natural circulation evaporator, U-shaped tube natural circulation evaporator or spiral tube natural circulation evaporator described in the present invention all refer to the tube type of the base tube.

[0047] Preferably, the dust removal device includes any one of an electrostatic precipitator, a gravity dust collector or a bag dust collector, or a combination of at least two of them, wherein 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 dust collector, a combination of a gravity dust collector and a bag dust collector, and a combination of an electrostatic precipitator, a gravity dust collector and a bag dust collector.

[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 openings of the water supply pump, the circulating water pump and the flue gas conveying device according to the measured temperature.

[0050] By arranging a flue gas temperature monitoring device in the recycling device, the present invention can perform real-time detection of the temperature of the flue gas discharged from the first flue gas outlet and form a feedback mechanism. When the flue gas temperature is lower than the set temperature, the motor speeds of the water supply pump and the circulating water pump will be reduced, thereby reducing the water supply flow entering the flue gas evaporator; and the speed of the flue gas conveying device will be reduced, thereby reducing the flue gas flow entering the flue gas evaporator, thereby reducing the operating load of the system when the sintering flue gas temperature fluctuates, thereby 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 20-40%, for example, it can be 20%, 25%, 30%, 35% or 40%, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0052] Preferably, when the temperature measured by the flue gas temperature monitoring device is equivalent 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, it can be 70%, 72%, 74%, 76%, 78% or 80%, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

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

[0054] In a second aspect, the present invention provides a method for recovering and utilizing waste heat from sintering machine flue gas, and the recovery and utilization method is performed using the device for recovering and utilizing waste heat from sintering machine flue gas described in the first aspect.

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

[0056] As a preferred technical solution of the present invention, the recycling method comprises the following steps:

[0057] The sintering raw meal is sintered to obtain sintered clinker and flue gas; wherein 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, and 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 first flue gas after heat exchange and the second flue gas after heat exchange are subjected to dust removal treatment and then discharged through a chimney;

[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 comprises: the sintered clinker is cooled after being discharged from the chute.

[0061] Preferably, the sintering raw meal comprises iron ore, limestone and coke.

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

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

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

[0065] Preferably, the shape of the sintered clinker includes a block.

[0066] Preferably, the particle size of the sintered clinker after the crushing 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 values ​​not listed within the above numerical range are also applicable.

[0067] The sintered clinker of the present invention contains incompletely reacted metal particles (such as Ni and Co), which can be recycled and reused. The present invention crushes the blocky sintered clinker so that the particle size of the sintered clinker after crushing is 5 to 50 mm. This can expose the incompletely reacted metal particles in the sintered clinker, facilitate gravity separation in the chute, and improve the metal recovery rate. At the same time, the sintered clinker with a particle size of 5 to 50 mm has a larger specific surface area, more complete contact with the cooling medium, and a uniform cooling rate, which can avoid local overheating or incomplete cooling during the subsequent cooling process.

[0068] Preferably, the cooling medium of the cooling treatment is air.

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

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

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

[0073] Preferably, the temperature of the second portion of flue gas is 230-270°C, for example, 230°C, 240°C, 250°C, 260°C or 270°C, but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

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

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

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

[0077] Preferably, the concentration of solid particles in the flue gas after dust removal is less than 15 mg / m 3 , for example, it can be 10 mg / m 3 , 11mg / m 3 , 12mg / m 3 , 13mg / m 3 or 14 mg / m 3 , but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0078] As a preferred technical solution of the present invention, the recycling method comprises the following steps:

[0079] The raw material is sintered at 1000-1400° C. for 6-10 hours to obtain a block-shaped sintered clinker and flue gas with a temperature of 700-900° C.; wherein a first portion of the flue gas with a temperature of 170-230° C. enters a forced circulation evaporator through a first flue gas outlet of the sintering machine for forced circulation heat exchange to obtain a first heat-exchanged flue gas with a temperature of 140-200° C., and a second portion of the flue gas with a temperature of 230-270° C. enters a natural circulation evaporator through a second flue gas outlet of the sintering machine for natural circulation heat exchange to obtain a second heat-exchanged flue gas with a temperature of 160-200° C.

[0080] The first heat-exchanged flue gas and the second heat-exchanged flue gas are mixed, dust-removed, and 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] The present invention increases the waste heat recovery efficiency by performing heat exchange treatment on the flue gas at different positions of the sintering machine, so that the recovery efficiency can preferably reach more than 40%. In addition, based on the location characteristics of different flue gas outlets of the sintering machine, a dual-operation system is adopted to reduce system energy consumption while rationally utilizing the plant space. Furthermore, the present invention reduces the temperature of the flue gas at the inlet of the dust removal device by limiting the placement of each device in the recycling device, so that the service life of the dust removal device can reach more than 2.5 years. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 It is a structural schematic diagram of the device for recovering and utilizing waste heat from sintering machine flue gas provided in Example 1 of the present invention.

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

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

[0087] Figure 4 Schematic diagram of the structure of the twisted tube in the forced circulation evaporator provided in Example 1 of the present invention.

[0088] Figure 5 This invention Figure 4 A partial enlarged schematic diagram of the twisted tube within the dotted box.

[0089] Figure 6 It is a structural schematic diagram of the device for recovering and utilizing waste heat from sintering machine flue gas provided in Comparative Example 3 of the present invention.

[0090] Figure 7 It is a structural schematic diagram of the device for recovering and utilizing waste heat from sintering machine flue gas provided in Comparative Example 4 of the present invention.

[0091] Figure 8 It is a structural schematic diagram of the device for recovering and utilizing waste heat from 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 mixed inlet;702-first liquid phase outlet;703-second gas-liquid mixed inlet;704-second liquid phase outlet;705-liquid phase inlet;706-gas phase outlet;8-water feed pump;9-dust removal device;901-first bag dust collector;902-second bag dust collector;10-flue gas conveying device;11-chimney;12-water tank;13-cooling device;14-chute. DETAILED DESCRIPTION

[0093] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through 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 shall be subject to the claims.

[0094] The present invention provides a device and method for recovering waste heat from flue gas of a sintering machine. Along the flue gas conveying direction, the device comprises 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 arranged at the tail of the sintering machine, and a chute arranged below the crushing device;

[0096] The sintering machine is provided with a fume hood, a first fume outlet is provided on the fume hood at the tail of the sintering machine, and the first fume outlet is provided above the pulverizing device, and a second fume outlet is provided on the fume 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 arranged 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 interface and a twisted-plate tube; the twisted-plate tubes in the forced circulation evaporator are arranged crosswise in the forced circulation evaporator; the twisted-plate tubes include twisted plates and a base tube; the twisted plates include a first twisted plate and a second twisted plate; the first twisted plate and the second twisted plate are symmetrically distributed along both sides of the base tube.

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

[0104] In some embodiments, 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 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 20-40%; when the temperature measured by the flue gas temperature monitoring device is equivalent 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%; wherein, the set temperature is 170-230°C.

[0105] The present invention performs different types of heat exchange treatment on the flue gas at different positions of the sintering machine to solve the problem of unstable steam production in the waste heat boiler caused by intermittent fluctuations in the flue gas temperature, increase the waste heat recovery efficiency, and limit the placement of each device 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 is described with reference to the embodiments:

[0107] Example 1

[0108] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas. 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, which are 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 a ring cooler.

[0109] The sintering machine 1 includes a crushing device 2 arranged at the tail of the sintering machine, and a chute 14 arranged below the crushing device 2; the sintering machine 1 is provided with a fume hood, and a first fume outlet 101 is provided on the fume hood at the tail of the sintering machine, and the first fume outlet 101 is provided above the crushing device 2, and a second fume outlet 102 is provided on the fume hood at the chute, and the chute 14 of the sintering machine is connected to the ring 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 arranged 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, and at the same time, the forced circulation evaporator 4 is respectively connected to the first gas-liquid mixing inlet 701 of the steam drum 7 and the The first liquid phase outlet 702 is connected, the circulating water pump 6 is arranged on the connecting pipe between the first liquid phase outlet 702 of the steam drum 7 and the forced circulation evaporator 4, and the natural circulation evaporator 5 is respectively connected to the second gas-liquid mixed 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, wherein the liquid phase inlet 705 is connected to the water tank 12, and the water supply pump 8 is arranged on the connecting pipe between the water tank 12 and the liquid phase inlet 705 of the steam drum 7, and the gas phase outlet 706 is connected to the plant steam network.

[0111] The left view and the front view of the forced circulation evaporator 4 are respectively as follows Figure 2 and Figure 3 As shown, the forced circulation evaporator includes a header 404, a shell 403, a flue gas interface 402 and a twisted tube 401; Figure 4 As shown, the forced circulation evaporator 4 includes 50 twisted-plate tubes 401; the twisted-plate tubes 401 are arranged crosswise in the forced circulation evaporator 4; the twisted-plate tubes 401 include twisted plates 4011 and base tubes 4012; Figure 5As shown, the twisting plates include 100 first twisting plates 40111 and 100 second twisting plates 40112; the first twisting plates 40111 and the second twisting plates 40112 are symmetrically distributed along the base tube 4012; and the distance between the first twisting plates 40111 is 100 mm.

[0112] The flue gas temperature monitoring device 3 includes a PID controller; the PID controller can control the valve openings 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 openings of the water supply pump, the circulating water pump and the flue gas conveying device are adjusted to 30%; when the temperature measured by the flue gas temperature monitoring device is equivalent to the set temperature, the valve openings of the water supply pump, the circulating water pump and the flue gas conveying device are adjusted to 75%; wherein, the set temperature is 200°C.

[0113] Example 2

[0114] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas. The device comprises, along the flue gas conveying direction, a sintering machine 1, a flue gas evaporator, a dust removal device 9, a flue gas conveying device 10, and a chimney 11, which are connected in sequence. The device also includes a flue gas temperature monitoring device 3, a circulating water pump 6, a steam drum 7, a feedwater 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 a ring cooler.

[0115] The sintering machine 1 includes a crushing device 2 arranged at the tail of the sintering machine, and a chute 14 arranged below the crushing device 2; the sintering machine 1 is provided with a fume hood, and a first fume outlet 101 is provided on the fume hood at the tail of the sintering machine, and the first fume outlet 101 is provided above the crushing device 2, and a second fume outlet 102 is provided on the fume hood at the chute, and the chute 14 of the sintering machine is connected to the ring 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 arranged 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, and at the same time, the forced circulation evaporator 4 is respectively connected to the first gas-liquid mixing inlet 701 and the first gas-liquid mixing inlet 702 of the steam drum 7. The first liquid phase outlet 702 is connected, the circulating water pump 6 is arranged 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 respectively connected to the second gas-liquid mixed 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, wherein the liquid phase inlet 705 is connected to the water tank 12, the feed water pump 8 is arranged on the connecting pipe between the water tank 12 and the liquid phase inlet 705 of the steam drum 7, and the gas phase outlet 706 is connected to the plant steam network.

[0117] The forced circulation evaporator 4 includes a header 404, a shell 403, a flue gas interface 402 and a twisted-plate tube 401 from the outside to the inside; the forced circulation evaporator 4 includes 10 twisted-plate tubes 401; the twisted-plate tubes 401 are cross-arranged in the forced circulation evaporator 4; the twisted-plate tube 401 includes a twisted plate 4011 and a base tube 4012; the 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 openings 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 openings of the water supply pump, the circulating water pump and the flue gas conveying device are adjusted to 40%; when the temperature measured by the flue gas temperature monitoring device is equivalent to the set temperature, the valve openings of the water supply pump, the circulating water pump and the flue gas conveying device are adjusted to 70%; wherein, the set temperature is 170°C.

[0119] Example 3

[0120] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas. The device comprises, along the flue gas conveying direction, a sintering machine 1, a flue gas evaporator, a dust removal device 9, a flue gas conveying device 10, and a chimney 11, which are connected in sequence. The 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 a ring cooler.

[0121] The sintering machine 1 includes a crushing device 2 arranged at the tail of the sintering machine, and a chute 14 arranged below the crushing device 2; the sintering machine 1 is provided with a fume hood, and a first fume outlet 101 is provided on the fume hood at the tail of the sintering machine, and the first fume outlet 101 is provided above the crushing device 2, and a second fume outlet 102 is provided on the fume hood at the chute, and the chute 14 of the sintering machine is connected to the ring 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 arranged 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, and at the same time, the forced circulation evaporator 4 is respectively connected to the first gas-liquid mixing inlet 701 and the first gas-liquid mixing inlet 702 of the steam drum 7. The first liquid phase outlet 702 is connected, the circulating water pump 6 is arranged 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 respectively connected to the second gas-liquid mixed 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, wherein the liquid phase inlet 705 is connected to the water tank 12, the feed water pump 8 is arranged on the connecting pipe between the water tank 12 and the liquid phase inlet 705 of the steam drum 7, and the gas phase outlet 706 is connected to the plant steam network.

[0123] The forced circulation evaporator 4 includes a header 404, a shell 403, a flue gas interface 402 and a twisted-plate tube 401 from the outside to the inside; the forced circulation evaporator 4 includes 100 twisted-plate tubes 401; the twisted-plate tubes 401 are cross-arranged in the forced circulation evaporator 4; the twisted-plate tube 401 includes a twisted plate 4011 and a base tube 4012; the 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 openings 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 openings of the water supply pump, the circulating water pump and the flue gas conveying device are adjusted to 20%; when the temperature measured by the flue gas temperature monitoring device is equivalent to the set temperature, the valve openings of the water supply pump, the circulating water pump and the flue gas conveying device are adjusted to 80%; wherein, the set temperature is 230°C.

[0125] Example 4

[0126] This embodiment provides a device for recovering and utilizing waste heat from sintering machine flue gas. The only difference from Example 1 is that, except that the twisted-fin tubes in the forced circulation evaporator do not include twisted fins, that is, the twisted-fin tubes in the forced circulation evaporator are only base tubes, the rest are the same as Example 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 Example 1 is that, except for the twisted-plate tubes being arranged in parallel in the forced circulation evaporator, the rest is the same as Example 1.

[0129] Example 6

[0130] This embodiment provides a device for recovering waste heat from sintering machine flue gas. The only difference from Example 1 is that, except for the distance between the first twisting plates being adjusted from 100 mm to 50 mm, the rest is the same as Example 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 Example 1 is that, except for the distance between the first twisting plates being adjusted from 100 mm to 150 mm, the rest is the same as Example 1.

[0133] Comparative Example 1

[0134] This comparative example provides a device for recovering and utilizing waste heat from sintering machine flue gas, which is the same as Example 1 except that the natural circulation evaporator is replaced by a straight tube forced circulation evaporator.

[0135] Comparative Example 2

[0136] This comparative example provides a device for recovering and utilizing waste heat from sintering machine flue gas, which is the same as Example 1 except that the forced circulation evaporator is replaced by a straight tube natural circulation evaporator.

[0137] Comparative Example 3

[0138] This comparative example provides a device for recovering and utilizing the waste heat of sintering machine flue gas, which differs from Example 1 only in that, except for the direction of flue gas transportation, the recovery and utilization device includes a sintering machine, a dust removal device, a flue gas evaporator, a flue gas transportation device and a chimney connected in sequence, that is, the dust removal device includes a first bag dust collector 901 and a second bag dust collector 902, the first bag dust collector 901 is respectively connected to the first flue gas outlet 101 and the forced circulation evaporator 4, and the second bag dust collector 902 is respectively connected to the second flue gas outlet 102 and the natural circulation evaporator 5, and the rest is the same as Example 1.

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

[0140] Comparative Example 4

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

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

[0143] Comparative Example 5

[0144] This comparative example provides a device for recovering and utilizing waste heat from flue gas of a sintering machine. The only difference from Example 1 is that, except that the sintering machine only includes a second flue gas outlet, the recovery and utilization device does not include a forced circulation evaporator, and a flue gas temperature monitoring device is arranged 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, the rest is the same as Example 1.

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

[0146] Application Example 1

[0147] This application example provides a method for recovering waste heat from sintering machine flue gas. The method is performed using the recovery device described in Example 1. The method comprises the following steps:

[0148] A sintering raw meal comprising iron ore, limestone, and coke is sintered at 1300° C. for 8 hours to obtain a block-shaped sintered clinker having a temperature of 800° C. and flue gas; wherein a first portion of the flue gas having a temperature of 200° C. enters a forced circulation evaporator through a first flue gas outlet of the sintering machine for forced circulation heat exchange to obtain a first heat-exchanged flue gas having a temperature of 170° C., and a second portion of the flue gas having a temperature of 250° C. enters a natural circulation evaporator through a second flue gas outlet of the sintering machine for natural circulation heat exchange to obtain a second heat-exchanged flue gas having a temperature of 180° C.; the volume ratio of the first portion of flue gas to the second portion of flue gas is 2:1;

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

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

[0151] Application Example 2

[0152] This application example provides a method for recovering waste heat from sintering machine flue gas. The method is performed using the recovery device described in Example 2. The method comprises the following steps:

[0153] A sintering raw meal comprising iron ore, limestone, and coke is sintered at 1000° C. for 10 hours to obtain a block-shaped sintered clinker having a temperature of 700° C. and flue gas; wherein a first portion of the flue gas having a temperature of 170° C. enters a forced circulation evaporator through a first flue gas outlet of the sintering machine for forced circulation heat exchange to obtain a first heat-exchanged flue gas having a temperature of 140° C., and a second portion of the flue gas having a temperature of 230° C. enters a natural circulation evaporator through a second flue gas outlet of the sintering machine for natural circulation heat exchange to obtain a second heat-exchanged flue gas having a temperature of 160° C.; the volume ratio of the first portion of flue gas to the second portion of flue gas is 1:1;

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

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

[0156] Application Example 3

[0157] This application example provides a method for recovering waste heat from sintering machine flue gas. The method is performed using the recovery device described in Example 3. The method comprises the following steps:

[0158] A sintering raw meal comprising iron ore, limestone, and coke is sintered at 1400° C. for 6 hours to obtain a lumpy sintered clinker having a temperature of 900° C. and flue gas; wherein a first portion of the flue gas having a temperature of 230° C. enters a forced circulation evaporator through a first flue gas outlet of the sintering machine for forced circulation heat exchange to obtain a first heat-exchanged flue gas having a temperature of 200° C., and a second portion of the flue gas having a temperature of 270° C. enters a natural circulation evaporator through a second flue gas outlet of the sintering machine for natural circulation heat exchange to obtain a second heat-exchanged flue gas having a temperature of 200° C.; the volume ratio of the first portion of flue gas to the second portion of flue gas is 4:1;

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

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

[0161] Application Example 4

[0162] This application example provides a method for recovering and utilizing the waste heat of 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, the rest is the same as Application Example 1.

[0163] Application Example 5

[0164] This application example provides a method for recovering and utilizing the waste heat of 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, the rest is the same as Application Example 1.

[0165] Application Example 6

[0166] This application example provides a method for recovering and utilizing the waste heat of 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, the rest is the same as Application Example 1.

[0167] Application Example 7

[0168] This application example provides a method for recovering and utilizing the waste heat of 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, the rest is the same as Application Example 1.

[0169] Comparative Application Example 1

[0170] This comparative application example provides a method for recovering and utilizing the waste heat of 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, the rest is the same as Application Example 1.

[0171] Comparative Application Example 2

[0172] This comparative application example provides a method for recovering and utilizing the waste heat of 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, the rest is the same as Application Example 1.

[0173] Comparative Application Example 3

[0174] This comparative application example provides a method for recycling waste heat from flue gas of a sintering machine. The recycling method is performed by using the recycling device described in comparative example 3. In addition, the recycling method is performed by using the recycling device provided in comparative example 3. The recycling method is adjusted as follows: sintering raw materials including iron ore, limestone and coke are sintered at 1300°C for 8 hours to obtain block-shaped sintered clinker and flue gas with a temperature of 800°C; wherein, the first part of the flue gas with a temperature of 200°C enters the first bag filter through the first flue gas outlet of the sintering machine for removal. After the dust treatment, the flue gas enters the forced circulation evaporator for forced circulation heat exchange to obtain a first flue gas after heat exchange with a temperature of 190°C. The second flue gas with a temperature of 250°C enters the second bag dust collector through the second flue gas outlet of the sintering machine for dust removal treatment and then enters the natural circulation evaporator for natural circulation heat exchange to obtain a second flue gas after heat exchange with a temperature of 200°C. The volume ratio of the first flue gas to the second flue gas is 2:1; except that the first flue gas after heat exchange and the second flue gas after heat exchange are mixed and discharged through a chimney, the rest are the same as Application Example 1.

[0175] Comparative Application Example 4

[0176] This comparative application example provides a method for recovering and utilizing waste heat from flue gas of a sintering machine. The recovery and utilization method is carried out using the recovery and utilization device described in comparative example 4. In addition to using the recovery and utilization device provided in comparative example 4, the recovery and utilization method is adjusted as follows: sintering raw materials including iron ore, limestone and coke are sintered at 1300°C for 8 hours to obtain block-shaped sintered clinker with a temperature of 800°C and flue gas with a temperature of 200°C; 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 heat-exchanged flue gas with a temperature of 170°C; the heat-exchanged flue gas is dust-removed to obtain dust-removed flue gas and is discharged through a chimney. The rest is the same as application example 1.

[0177] Comparative Application Example 5

[0178] This comparative application example provides a method for recovering and utilizing waste heat from flue gas of a sintering machine. The recovery and utilization method is carried out using the recovery and utilization device described in the comparative example, except that the recovery and utilization method is carried out using the recovery and utilization device provided in comparative example 5, and the recovery and utilization method is adjusted as follows: the sintering raw material including iron ore, limestone and coke is sintered at 1300°C for 8 hours to obtain block sintered clinker with a temperature of 800°C and flue gas with a temperature of 250°C; 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 heat-exchanged flue gas with a temperature of 180°C; the heat-exchanged flue gas is dust-removed to obtain dust-removed flue gas and is discharged through a chimney. The rest is the same as application example 1.

[0179] The present invention calculates the sensible heat recovery efficiency η by 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℃, Q1 is the exhaust gas flow rate of the first exhaust gas outlet, the unit is m 3 / h, Q is the sum of the flue gas flow rates discharged from the first flue gas outlet and the second flue gas outlet, the unit is m 3 / h;

[0180] Similarly, the sensible heat recovery efficiency of the flue gas discharged from the second flue gas outlet is: Q2 is the flue gas flow rate discharged from the second flue gas outlet, the unit is m 3 / h, sensible heat recovery efficiency η=η1+η2, the concentration of solid particles in the flue gas after dust removal is tested, when the concentration of solid particles in the flue gas after dust removal reaches 20mg / m 3 , the dust removal device needs to be replaced. The service life of the dust removal device is the service life of the dust removal device. When the flue gas sensible heat recovery efficiency drops to 80% of the initial flue gas sensible heat recovery efficiency, the twisted-plate tubes in the forced circulation evaporator need to be replaced. The service life of the twisted-plate tubes is the service life of the twisted-plate tubes. 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) It can be seen from Application Examples 1 to 3 that the present invention solves the problem of unstable steam production in the waste heat boiler caused by intermittent fluctuations in flue gas temperature by performing different types of heat exchange treatment on the flue gas at different positions of the sintering machine, thereby increasing the waste heat recovery efficiency, and its sensible heat recovery efficiency can reach more than 33.74%. The placement position of each device in the recycling device is limited to reduce the temperature of the 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) It can be seen from Application Examples 1 and 4-7 that the present invention further optimizes the structure of the flue gas evaporator so that the twisted-blade tubes in the flue gas evaporator are arranged crosswise, so that the flue gas outside the twisted-blade tube flows in the curved channel that alternately expands and contracts between the tubes, thereby enhancing the flue gas disturbance and improving the convective heat transfer coefficient, so as to improve the heat exchange efficiency between the flue gas and the saturated water in the twisted-blade tube. The structure of the twisted blades in the twisted-blade tube is designed so that the flue gas can generate centrifugal force when passing through the twisted-blade tube, so that the dust in the flue gas is thrown out. The dust particles are not easy to adhere to the surface of the twisted-blade tube and are more likely to fall under the action of vibration or wind, which can prevent the twisted-blade tube from bridging and causing blockage. At the same time, the flue gas can flow turbulently between the twisted blades to enhance the heat exchange efficiency; reduce the local scouring of the flue gas on the tube wall of the twisted-blade tube, increase the service life of the twisted-blade tube, and ultimately increase the sensible heat recovery efficiency and increase the service life of the dust removal device and the twisted-blade tube.

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

[0187] (4) It can be seen from Application Example 1 and Comparative Application Example 3 that 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 utilize the special structure of the flue gas evaporator to remove a part of the dust particles, so as to increase the sensible heat recovery efficiency and extend the service life of the dust removal device.

[0188] (5) It can be seen from Application Example 1 and Comparative Application Examples 4-5 that the present invention provides a first flue gas outlet and a second flue gas outlet at the tail of the sintering machine and on the chute of the sintering machine, respectively, and connects the first flue gas outlet and the second flue gas outlet to the forced circulation evaporator and the natural circulation evaporator, respectively, 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, the present invention increases the waste heat recovery efficiency by performing heat exchange treatment on the flue gas at different positions of the sintering machine, so that the recovery efficiency reaches more than 33.74%. In addition, based on the location characteristics of different flue gas outlets of the sintering machine, a dual-operation system is adopted to rationally utilize the plant space while reducing system energy consumption. Furthermore, the present invention reduces the temperature of the flue gas at the inlet of the dust removal device by limiting the placement of each device in the recycling device, so that the service life of the dust removal device can reach more than 2.5 years. The structure of the flue gas evaporator is designed so that the service life of the flue gas evaporator can reach more than 4.8 years.

[0190] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure 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 arranged at the tail of the sintering machine, and a chute arranged below the crushing device; The sintering machine is provided with a fume hood, a first fume outlet is provided on the fume hood at the tail of the sintering machine, and a second fume outlet is provided on the fume 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.

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; Preferably, the chute of the sintering machine is connected to the cooling device; Preferably, the first smoke outlet is arranged above the pulverizing device; Preferably, the flue gas temperature monitoring device is provided on a 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 recycling device also includes a steam drum, a water tank, a feed water pump and a circulating water pump; Preferably, the forced circulation evaporator, the natural circulation evaporator and the water tank are all connected to the steam drum; Preferably, the steam drum is provided with a gas-liquid mixed inlet, a liquid phase inlet, a liquid phase outlet and a gas phase outlet; Preferably, the gas-liquid mixed inlet includes a first gas-liquid mixed inlet and a second gas-liquid mixed inlet; Preferably, the liquid phase outlet includes a first liquid phase outlet and a second liquid phase outlet; Preferably, the first gas-liquid mixed inlet and the first liquid phase outlet are respectively connected to the forced circulation evaporator; Preferably, the second gas-liquid mixed inlet and the second liquid phase outlet are respectively connected to the natural circulation evaporator; Preferably, the water tank is connected to the liquid phase inlet of the steam drum; Preferably, the water feed pump is provided on a connecting pipe between the water tank and the liquid phase inlet of the steam drum; Preferably, the circulating water pump is provided on the connecting pipe between the first liquid phase outlet of the steam drum and the forced circulation evaporator; Preferably, the gas phase outlet of the steam drum is connected to the plant steam network.

4. The recycling device according to any one of claims 1 to 3, characterized in that: The forced circulation evaporator includes a header, a shell, a flue gas interface and a twisted tube; Preferably, the forced circulation evaporator comprises at least two twisted-plate tubes; Preferably, the twisted-plate tubes are arranged crosswise in the forced circulation evaporator.

5. The recycling device according to claim 4, characterized in that: The twisted sheet tube comprises a twisted sheet and a base tube; Preferably, the twisting plate includes a first twisting plate and a second twisting plate; Preferably, the first twisting plate and the second twisting plate are respectively arranged on both sides of the base tube; Preferably, the first twisted plate and the second twisted plate are symmetrically distributed along the base tube; Preferably, the twisting plate includes at least two first twisting plates; Preferably, the distance between the first twisting pieces is 80-120 mm.

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

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

8. The recycling method according to claim 7, characterized in that: The recycling method comprises the following steps: The sintering raw meal is sintered to obtain sintered clinker and flue gas; wherein 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, and 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 first flue gas after heat exchange and the second flue gas after heat exchange are subjected to dust removal treatment and then discharged through a chimney; 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 comprises: cooling the sintered clinker after it is discharged from the chute; Preferably, the sintering raw meal comprises iron ore, limestone and coke; Preferably, the sintering temperature is 1000-1400°C; Preferably, the sintering treatment time is 6 to 10 hours; Preferably, the temperature of the sintered clinker is 700-900°C; Preferably, the temperature of the sintered clinker after the cooling treatment is 80-150°C.

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; Preferably, the temperature of the first portion of flue gas is 170-230°C; Preferably, the temperature of the flue gas after the first heat exchange is 140-200°C; Preferably, the temperature of the second portion of flue gas is 230-270°C; Preferably, the temperature of the flue gas after the second heat exchange is 160-200°C.

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