A waste heat utilization device for chain grate rotary kiln

Abstract

The present invention discloses a waste heat utilization device for a chain grate rotary kiln, which belongs to the technical field of cascade utilization of low-quality heat sources, and solves the problems of direct discharge of low-temperature tail gas and low waste heat recovery rate in the production process of chain grate rotary kiln pellets in the prior art. The device includes a chain grate, a rotary kiln, a ring cooler, a vertical cooling kiln, a discharge assembly and a gas heat exchanger, and the gas outlet of the vertical cooling kiln is connected to the gas heat exchanger; the third section of the ring cooling has a normal cooling mode and an emergency cooling mode; the third section of the ring cooling is in the normal cooling mode, the cooling fan that provides cooling air to the third section of the ring cooling is not working, and the discharge port of the vertical cooling kiln is connected to the discharge assembly; the third section of the ring cooling is in the emergency cooling mode, the cooling fan that provides cooling air to the third section of the ring cooling is turned on, and the discharge port of the third section of the ring cooling is connected to the discharge assembly. The device and the method can be used for sensible heat recovery of chain grate rotary kiln pellets.

Description

Technical Field

[0001] The invention belongs to the technical field of cascade utilization of low-quality heat sources, and in particular relates to a waste heat utilization device for a chain grate rotary kiln. Background Art

[0002] At present, the production process of chain grate rotary kiln pellets mainly adopts ring cooler or belt cooler to cool the finished pellets.

[0003] The above two pellet cooling methods have the following disadvantages:

[0004] On the one hand, due to the large number of joint surfaces with structural parts such as bellows and smoke hoods, the equipment has a high air leakage rate.

[0005] On the other hand, the flue gas temperature in the low-temperature section is low and has little recovery value, so it is generally discharged directly, resulting in low waste heat recovery efficiency and large energy waste in the pellet cooling link; at the same time, it will also bring about particulate matter emissions, causing environmental pollution. Summary of the invention

[0006] In view of the above analysis, the present invention aims to provide a waste heat utilization device for a chain grate rotary kiln, which solves the problems of direct emission of low-temperature tail gas and low waste heat recovery rate in the production process of chain grate rotary kiln pellets in the prior art.

[0007] The purpose of the present invention is mainly achieved through the following technical solutions:

[0008] The present invention provides a waste heat utilization device for a chain grate rotary kiln, comprising a chain grate, a rotary kiln, a ring cooler, a vertical cooling kiln, a discharge assembly and a gas heat exchanger for providing heating gas for the chain grate and the rotary kiln, wherein the gas outlet of the vertical cooling kiln is connected to the gas heat exchanger for preheating the heating gas in the gas heat exchanger; along the direction from the feed port to the discharge port, the cooling space in the ring cooler is divided into a first ring cooling section, a second ring cooling section and a third ring cooling section, and the third ring cooling section has a normal cooling mode and an emergency cooling mode; when the third ring cooling section is in the normal cooling mode, the third ring cooling section is disconnected from a cooling fan for providing cooling air, and the discharge port of the vertical cooling kiln is connected to the discharge assembly; when the third ring cooling section is in the emergency cooling mode, the third ring cooling section is connected to a cooling fan for providing cooling air, and the discharge port of the third ring cooling section is connected to the discharge assembly.

[0009] Furthermore, the discharge port of the third stage of the ring cooling is connected to the feed port or the discharge assembly of the vertical cooling kiln through a chain conveyor.

[0010] Furthermore, the chain plate machine includes a first chain plate and a second chain plate which are arranged in sequence along the direction from the discharge port of the ring cooler to the feed port of the vertical cooling kiln; the waste heat utilization device also includes a conveyor belt; the discharge end of the first chain plate is respectively connected to the feed end of the second chain plate and the feed end of the conveyor belt through a discharge changing assembly, the discharge end of the second chain plate is connected to the feed port of the vertical cooling kiln, the feed end of the conveyor belt is also connected to the discharge port of the vertical cooling kiln, and the discharge changing assembly is used for switching the discharge end of the first chain plate between normal cooling mode and emergency cooling mode.

[0011] Furthermore, the discharge redirection assembly includes a baffle and an interconnected discharge pipe, a chain plate feed pipe and a conveying feed pipe, the feed port of the discharge pipe is connected to the discharge end of the first chain plate, the discharge port of the chain plate feed pipe is connected to the feed end of the second chain plate, the discharge port of the conveying feed pipe is connected to the feed end of the conveyor belt, and one end of the baffle is rotatably connected to the inner wall of the connection area of ​​the discharge pipe, the chain plate feed pipe and the conveying feed pipe, so that the baffle blocks the feed port of the chain plate feed pipe or the feed port of the conveying feed pipe.

[0012] Furthermore, the first chain plate and the second chain plate are both inclined upward, and the discharge end of the first chain plate is located above the feed end of the second chain plate and above the feed end of the conveyor belt.

[0013] Furthermore, the core and / or side walls of the vertical cooling kiln are provided with air inlet pipes.

[0014] Furthermore, a rotary sealing valve is provided at the discharge port of the vertical cooling kiln.

[0015] Furthermore, the rotary sealing valve comprises a plurality of wind shields pivoted with the inner wall of the vertical cooling kiln, the plurality of wind shields form an umbrella-shaped structure, and the tip of the umbrella-shaped structure faces a direction away from the vertical cooling kiln.

[0016] Furthermore, there is no gap between two adjacent wind shields and between a wind shield and the inner wall of the vertical cooling kiln.

[0017] Furthermore, a spare cold air component is provided outside the discharge port of the vertical cold kiln.

[0018] The present invention also provides a waste heat utilization method for a chain grate rotary kiln, using the above-mentioned waste heat utilization device, and the waste heat utilization method comprises the following steps:

[0019] The green balls are sequentially dried and preheated by a chain grate, sintered by a rotary kiln, and cooled for the first time by the first and second stages of a ring cooler to obtain pellets;

[0020] The pellets are cooled for the second time, and the second cooling has a normal cooling mode and an emergency cooling mode. In the normal cooling mode, the vertical cooling kiln is used for the second cooling, and the third ring cooling section of the ring cooler does not provide cooling air; if the vertical cooling kiln fails, it switches to the emergency cooling mode, and only the third ring cooling section is used for the second cooling of the pellets;

[0021] The air after heat exchange with the pellets in the vertical cooling kiln is used to preheat the heating gas for sintering in the rotary kiln and provide combustion air for gas combustion.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] A) In the waste heat utilization device for the chain grate rotary kiln provided by the present invention, a vertical cooling kiln is added after the third ring cooling section of the ring cooler, and the third ring cooling section has a normal cooling mode and an emergency cooling mode. The vertical cooling kiln and the third ring cooling section of the ring cooler can be used to cool the pellets respectively, which can effectively increase the sensible heat utilization efficiency of the existing chain grate rotary kiln pellets, maximize the recovery of waste heat resources in the process, and realize the maximum utilization and cascade utilization of energy.

[0024] B) In the prior art, the third stage of the ring cooling is used for cooling, and the gas temperature at the outlet of the third stage of the ring cooling can only reach 150-200°C. This temperature range is relatively low and basically does not require reuse. In the present invention, in normal mode, by adding a vertical cooling kiln and closing the cooling fan of the third stage of the ring cooling, the temperature of the pellets discharged from the second stage of the ring cooling remains basically unchanged or the temperature drops slightly (usually within 10°C) in the third stage of the ring cooling. The pellets discharged from the third stage of the ring cooling are cooled by heat exchange with reverse air in the vertical cooling kiln. At the outlet of the vertical cooling kiln, the temperature of the air can rise to 300-350°C, which is used to preheat the sintering gas for the rotary kiln and / or dry the iron ore concentrate, which can effectively increase the sensible heat utilization efficiency of the existing chain grate rotary kiln pellets.

[0025] C) In the waste heat utilization device for the chain grate rotary kiln provided by the present invention, in actual application, the energy consumption of the cooling fan of the third ring cooling stage of the ring cooler is basically the same as that of the vertical cooling kiln. By stopping the cooling fan of the third ring cooling stage of the ring cooler, not only the energy consumption of the existing chain grate rotary kiln production process can be reduced, but also the waste heat recovery amount of the pellet ore can be increased, the electricity and gas consumption of the chain grate rotary kiln pellet production can be reduced, energy can be saved, and costs can be reduced.

[0026] D) In ​​the waste heat utilization device for the chain grate rotary kiln provided by the present invention, the waste heat utilization device of the present invention does not require major changes to the existing production process and equipment, does not change the overall process equipment of the existing chain grate rotary kiln, is suitable for upgrading and transforming the existing system, has a simple equipment structure, and has low transformation cost; at the same time, when a failure occurs in the vertical cooling kiln, it can be promptly switched to the third ring cooling section of the ring cooler for cooling, which basically does not disrupt the production rhythm of the chain grate rotary kiln pelletizing ore.

[0027] E) In the waste heat utilization device for the chain grate rotary kiln provided by the present invention, compared with removing the third stage of the ring cooling of the ring cooler, the pellets are all cooled and heat-exchanged by vertical cooling. The present invention adds a vertical cooling kiln on the basis of almost no changes to the existing production process and equipment, and can have a normal working mode and an emergency working mode at the same time, rather than an either-or relationship, and has great engineering application value.

[0028] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0030] Figure 1 A process schematic diagram of a waste heat utilization device for a chain grate rotary kiln provided by the present invention;

[0031] Figure 2 A partial schematic diagram of a waste heat utilization device for a chain grate rotary kiln provided by the present invention;

[0032] Figure 3 A schematic diagram of the structure of a discharge direction-changing assembly in a waste heat utilization device for a chain grate rotary kiln provided by the present invention;

[0033] Figure 4 A schematic diagram of the structure of a rotary sealing valve in a waste heat utilization device for a chain grate rotary kiln provided by the present invention;

[0034] Figure 5 A schematic structural diagram of a rotary sealing valve and a return air ring in a waste heat utilization device for a chain grate rotary kiln provided by the present invention.

[0035] Reference numerals:

[0036] 1-chain grate machine; 2-rotary kiln; 3-annular cooler; 31-annular cooling first section; 32-annular cooling second section; 33-annular cooling third section; 4-vertical cooling kiln; 5-cyclone dust collector; 6-gas heat exchanger; 7-conveyor belt; 8-chain plate machine; 81-first chain plate; 82-second chain plate; 83-baffle; 84-discharge pipe; 85-chain plate inlet pipe; 86-conveying inlet pipe; 9-wind shield; 91-fixed plate; 92-rotating plate; 10-return air ring. DETAILED DESCRIPTION

[0037] Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0038] The present invention provides a waste heat utilization device for a chain grate rotary kiln, see Figure 1 to Figure 2 , including an iron ore concentrate dryer, a pelletizing machine, a chain grate 1, a rotary kiln 2, an annular cooler 3, a vertical cooling kiln 4, a discharge assembly, and a gas heat exchanger 6 for providing heating gas to the chain grate 1 and the rotary kiln 2, wherein the gas outlet of the vertical cooling kiln 4 is connected to the gas heat exchanger 6 through a cyclone dust collector 5 and a gas heat exchanger, and is used to preheat the heating gas in the gas heat exchanger 6;

[0039] Along the direction from the feed port to the discharge port, the cooling space in the ring cooler 3 is divided into a first ring cooling section 31, a second ring cooling section 32 and a third ring cooling section 33, and the third ring cooling section 33 has a normal cooling mode and an emergency cooling mode;

[0040] The third ring cooling section 33 is in normal cooling mode, the third ring cooling section 33 is disconnected from the cooling fan providing cooling air, the discharge port of the vertical cooling kiln 4 is connected to the discharge assembly, and the pellets pass through the third ring cooling section 33 and the vertical cooling kiln 4 in sequence and then enter the discharge assembly;

[0041] The third section 33 of the ring cooling is in emergency cooling mode. The third section 33 of the ring cooling is connected to a cooling fan that provides cooling air. The discharge port of the third section 33 of the ring cooling is connected to a discharge assembly. The pellets pass through the third section 33 of the ring cooling and directly enter the discharge assembly.

[0042] During implementation, the waste heat utilization method of the waste heat utilization device comprises the following steps:

[0043] Step 1: Add a vertical cooling kiln 4 at the discharge port of the ring cooler 3 of the chain grate rotary kiln;

[0044] Step 2: Dry and adjust the moisture of the iron ore concentrate to make green balls. It should be noted that in this step, the moisture in the iron ore concentrate is not completely removed by drying, but only the moisture of the iron ore concentrate is adjusted;

[0045] Step 3: The green balls are sequentially dried and preheated by a chain grate 1, sintered by a rotary kiln 2, and cooled for the first time by the first ring cooling section 31 and the second ring cooling section 32 of a ring cooler 3 to obtain pellets;

[0046] Step 4: performing a second cooling on the pellets, wherein the second cooling has a normal cooling mode and an emergency cooling mode;

[0047] Among them, in the normal cooling mode, the vertical cooling kiln 4 works normally, the third ring cooling section 33 of the ring cooler 3 does not provide cooling air, and the pellets discharged from the third ring cooling section 33 are cooled for the second time by the vertical cooling kiln 4. In the vertical cooling kiln 4, the pellets are cooled by heat exchange with reverse air, so that the temperature of the air rises to 300-350°C, and the temperature of the pellets drops to below 120°C, and then the waste heat is utilized and the material is discharged; if a fault occurs in the vertical cooling kiln 4, it switches to the emergency cooling mode, and only the third ring cooling section is used to cool the pellets for the second time, so that the temperature of the pellets drops to below 120°C, reaching a temperature acceptable to the feeding belt;

[0048] Step 5: the air after heat exchange with the pellets in the vertical cooling kiln 4 is used to preheat the heating gas for sintering in the rotary kiln 2 after dust removal, and the temperature of the heating gas is preheated to 200-250° C., and / or the air after heat exchange with the pellets in the vertical cooling kiln 4 is used to dry the iron ore concentrate;

[0049] The pellets after the second cooling are sent to the discharge assembly through the conveyor belt 7.

[0050] It should be noted that the above-mentioned waste heat utilization device is particularly suitable for chain grate rotary kilns with an annual output of 1.2 million tons or less that use coal gas as fuel.

[0051] Compared with the prior art, in the waste heat utilization device for the chain grate rotary kiln provided by the present invention, a vertical cooling kiln 4 is additionally provided after the third ring cooling section 33 of the ring cooler 3, and the third ring cooling section 33 has a normal cooling mode and an emergency cooling mode. The vertical cooling kiln 4 and the third ring cooling section 33 of the ring cooler 3 can be used to cool the pellets respectively, which can effectively increase the sensible heat utilization efficiency of the existing chain grate rotary kiln pellets, maximize the recovery of waste heat resources in the process, and realize the maximum utilization and cascade utilization of energy.

[0052] Specifically, on the one hand, in the prior art, the third section 33 of the ring cooling is used for cooling, and the gas temperature at the outlet of the third section 33 of the ring cooling can only reach 150-200°C. This temperature range is relatively low and basically has no value for reuse. In the present invention, in normal mode, by adding a vertical cooling kiln 4 and closing the cooling fan of the third section 33 of the ring cooling, the temperature of the pellets discharged from the second section 32 of the ring cooling is basically unchanged in the third section 33 of the ring cooling or the temperature drop is small (usually within 10°C). The pellets discharged from the third section 33 of the ring cooling are cooled by heat exchange with reverse air in the vertical cooling kiln 4. At the outlet of the vertical cooling kiln 4, the temperature of the air after heat exchange can rise to 300-350°C, which is used to preheat the sintering gas for the rotary kiln 2 and / or dry the iron ore concentrate, which can effectively increase the sensible heat utilization efficiency of the existing chain grate rotary kiln pellets.

[0053] On the other hand, in actual application, the energy consumption of the cooling fan of the third ring cooling stage 33 of the ring cooler 3 is basically the same as that of the vertical cooling kiln 4. By stopping the cooling fan of the third ring cooling stage 33 of the ring cooler 3, not only the energy consumption of the existing chain grate rotary kiln production process can be reduced, but also the amount of waste heat recovery of pellets can be increased, the electricity and gas consumption of the chain grate rotary kiln pellet production can be reduced, energy can be saved, and costs can be reduced.

[0054] On the other hand, the waste heat utilization device of the present invention does not require major changes to the existing production processes and equipment, does not change the overall process equipment of the existing chain grate rotary kiln, is suitable for upgrading and transforming the existing system, has a simple equipment structure, and has low transformation cost; at the same time, when the vertical cooling kiln 4 fails, it can be switched to the third ring cooling section 33 of the ring cooler 3 for cooling in time, which basically does not disrupt the production rhythm of the chain grate rotary kiln pelletizing ore.

[0055] It should be noted that, compared with removing the ring cooler 3 and cooling and exchanging heat entirely through vertical cooling of the pellets, the present invention adds a vertical cooling kiln 4 on the basis of almost no changes to the existing production process and equipment, and can have both a normal working mode and an emergency working mode, rather than an either-or relationship, and has great engineering application value.

[0056] In order to transport the pellets from the ring cooler 3 to the vertical cooling kiln 4, the discharge port of the ring cooler 3 (i.e., the discharge port of the third ring cooling section 33 of the ring cooler 3) is connected to the feed port or the discharge assembly of the vertical cooling kiln 4 via a material tank or a chain conveyor 8, and the pellets discharged from the ring cooler 3 are transported to the vertical cooling kiln 4 or the discharge assembly via the material tank or the chain conveyor 8 for cooling and heat exchange.

[0057] It is worth noting that the second cooling adopts different cooling modes (i.e., normal cooling mode and emergency cooling mode), and the discharge position of the pelletized ore is different. In order to switch the discharge position when switching between the normal cooling mode and the emergency cooling mode, the discharge port of the above-mentioned ring cooler 3 is connected to the feed port of the vertical cooling kiln 4 through a chain plate machine 8. The chain plate machine 8 includes a first chain plate 81 and a second chain plate 82 sequentially arranged along the direction from the discharge port of the ring cooler 3 to the feed port of the vertical cooling kiln 4. The above-mentioned waste heat utilization device also includes a conveyor belt 7. The discharge end of the first chain plate 81 is connected to the feed end of the second chain plate 82 and the feed end of the conveyor belt 7 respectively through the discharge redirection assembly, the discharge end of the second chain plate 82 is connected to the feed port of the vertical cooling kiln 4, and the feed end of the conveyor belt 7 is also connected to the discharge port of the vertical cooling kiln 4. It should be noted that in the normal cooling mode, the discharge end of the first chain plate 81 is connected to the feed end of the second chain plate 82 through the discharge redirection assembly, and the discharge redirection assembly is used for the discharge of the discharge end of the first chain plate 81 switching between the normal cooling mode and the emergency cooling mode. In this way, the design of the chain plate machine 8 structure divides a complete chain plate into the first chain plate 81 and the second chain plate 82, and the discharge end of the first chain plate 81 can be switched between the feed end of the second chain plate 82 and the feed end of the conveyor belt 7 through the discharge redirection assembly, so as to realize the discharge switching between the normal cooling mode and the emergency cooling mode.

[0058] As for the structure of the discharge redirecting assembly, specifically, it includes a baffle 83 and a discharge pipe 84, a chain plate feed pipe 85 and a conveying feed pipe 86 that are interconnected. The feed port of the discharge pipe 84 is connected to the discharge end of the first chain plate 81, the discharge port of the chain plate feed pipe 85 is connected to the feed end of the second chain plate 82, and the discharge port of the conveying feed pipe 86 is connected to the feed end of the conveyor belt 7. One end of the baffle 83 is rotatably connected to the inner wall of the connection area of ​​the discharge pipe 84, the chain plate feed pipe 85 and the conveying feed pipe 86, so that the baffle 83 blocks the feed port of the chain plate feed pipe 85 or the feed port of the conveying feed pipe 86.

[0059] In order to utilize the gravity of the pelletized ore to discharge from the first chain plate 81 to the second chain plate 82 or the conveyor belt 7, the first chain plate 81 and the second chain plate 82 are both inclined upward, and the discharge end of the first chain plate 81 is located above the feed end of the second chain plate 82 and above the feed end of the conveyor belt 7.

[0060] It can be understood that it also includes a discharging unit, a storage unit and / or a cooling chamber, and the discharging end of the conveyor belt 7 is connected to the discharging unit, the storage unit and / or the cooling chamber.

[0061] A gate is provided at the bottom of the storage unit, and the pellets in the storage unit can be quickly discharged by opening the gate.

[0062] In order to supply air from the core and / or surroundings of the vertical cooling kiln 4, the core and / or side walls of the vertical cooling kiln 4 are provided with air inlet pipes, and reverse air is blown into the vertical cooling kiln 4 through the air inlet pipes.

[0063] In order to reduce the amount of cold air leaking into the vertical cooling kiln 4 when the pellets are discharged from the vertical cooling kiln 4, a rotary sealing valve is provided at the discharge port of the vertical cooling kiln 4. Specifically, the structure of the rotary sealing valve includes a plurality of wind shields 9, which form an umbrella-shaped structure. The tip of the umbrella-shaped structure faces away from the vertical cooling kiln 4. There is no gap between two adjacent wind shields 9 and between the wind shield 9 and the inner wall of the vertical cooling kiln 4. The wind shield 9 includes a fixed plate 91 and a rotating plate 92. The fixed plate 91 has a There are arcuate edges and straight edges, and the shape of the rotating plate 92 is triangular. The arcuate edges are fixedly connected to the inner wall of the vertical cooling kiln 4, and the straight edges are pivoted with the rotating plate 92. In this way, when the pellets are discharged, the rotating plate 92 can be rotated a certain angle away from the vertical cooling kiln 4 under the action of the pellets, and the rotating plate 92 can adjust the rotation angle in real time according to the discharge amount and discharge speed of the pellets, thereby reducing the gap between the pellets and the rotating plate 92, thereby reducing the amount of cold air leaking into the vertical cooling kiln 4 when the pellets are discharged.

[0064] In order to further reduce the amount of cold air leaking into the vertical cooling kiln 4 when the pellets are discharged, a return air ring 10 may be provided at the discharge port of the vertical cooling kiln 4. The cross-sectional shape of the return air ring 10 along the radial direction is a semicircular arc, and the return air ring 10 is concave toward the vertical cooling kiln 4. In this way, when the cold air leaks into the rotary kiln 2, the cold air will be blown into the return air ring 10. The flow direction of the cold air can be changed through the return air ring 10 to make it flow away from the vertical cooling kiln 4, thereby further reducing the amount of cold air leaking into the vertical cooling kiln 4 when the pellets are discharged.

[0065] In order to prevent the discharge temperature of the vertical cooling kiln 4 from being too high and burning the conveyor belt 7 in the event of an accident, a spare cold air component is also provided outside the discharge port of the vertical cooling kiln 4, and the air supply volume is 200-400m 3 / t.

[0066] The present invention also provides a waste heat utilization method for a chain grate rotary kiln, using the above-mentioned waste heat utilization device, and the waste heat utilization method comprises the following steps:

[0067] Step 1: Add a vertical cooling kiln 4 at the discharge port of the ring cooler 3 of the chain grate rotary kiln;

[0068] Step 2: wet and dry the iron ore concentrate to make raw balls;

[0069] Step 3: The green balls are sequentially dried and preheated by a chain grate 1, sintered by a rotary kiln 2, and cooled for the first time by the first ring cooling section 31 and the second ring cooling section 32 of a ring cooler 3 to obtain pellets;

[0070] Step 4: performing a second cooling on the pellets, wherein the second cooling has a normal cooling mode and an emergency cooling mode;

[0071] Among them, in the normal cooling mode, the vertical cooling kiln 4 works normally, the third ring cooling section 33 of the ring cooler 3 does not provide cooling air, and the pellets discharged from the third ring cooling section 33 are cooled for the second time by the vertical cooling kiln 4. In the vertical cooling kiln 4, the pellets are cooled by heat exchange with the reverse air, so that the temperature of the air rises to 300-350°C, and the temperature of the pellets drops to below 120°C, and then the waste heat is utilized and discharged; the vertical cooling kiln 4 switches to the emergency cooling mode when a fault occurs, and only the third ring cooling section is used to cool the pellets for the second time, so that the temperature of the pellets;

[0072] Step 5: the air after heat exchange with the pellets in the vertical cooling kiln 4 is used to preheat the heating gas for sintering in the rotary kiln 2 after dust removal, and the temperature of the heating gas is preheated to 200-250° C., and / or the air after heat exchange with the pellets in the vertical cooling kiln 4 is used to dry the iron ore concentrate;

[0073] The pellets after the second cooling are sent to the discharge assembly through the conveyor belt 7.

[0074] Compared with the prior art, the beneficial effects of the waste heat utilization method for a chain grate rotary kiln provided by the present invention are substantially the same as the beneficial effects of the waste heat utilization device provided above, and are not described in detail herein.

[0075] Embodiment 1

[0076] Taking the existing 1.2 million tons / year chain grate rotary kiln of a certain factory as an example, at present, the ring cooler has three cooling stages (ring cooling stage 1, ring cooling stage 2 and ring cooling stage 3). The hot air from the first stage directly enters the rotary kiln after heat exchange with the pellets; the cold air from the second stage of the ring cooler exchanges heat with the pellets and enters the chain grate to preheat the pellets, with an air volume of 60,000m 3 / h; the pellets enter the third stage of the ring cooler at a temperature of 420-450°C. The third stage of the ring cooler draws cold air to cool the pellets. The tail gas temperature after cooling is 150-200°C and is directly discharged. The air volume is about 100,000m 3 / h.

[0077] Vertical cooling design parameters of this embodiment:

[0078] The design of the vertical kiln is calculated based on the maximum daily output. The maximum processing capacity of the pellets entering the vertical cooling kiln is 150t / h. The height of the vertical cooling kiln is 21m, the maximum diameter is 7.5m, the maximum design temperature of the pellet inlet is 450℃, the outlet temperature of the pellet is 120℃, the number of air inlets is 2, the number of wind caps in the kiln is 7, and the maximum air volume of the cooling fan of the vertical cooling kiln is 90000Nm 3 / h, the blast temperature is 105℃, the wind pressure is 5500Pa, and the fan power is 400kW; the discharge facilities include vibrating dischargers, the number of vibrating dischargers is 6, and the feeding capacity is 55m 3 / h, the conveying capacity of the conveyor belt is 150t / h, and the displacement of the standby cold air component is 35000Nm 3 / h, the blast temperature is 20℃, the wind pressure is 5000Pa, and the fan power is 90kW.

[0079] Implementation effect: After the waste heat utilization energy-saving transformation, the blast furnace gas volume saved is 4130Nm 3 / h, saving more than 33 million Nm3 of gas per year 3 Compared with the original system, the power consumption has not increased, and the energy-saving and carbon-reduction effects are obvious.

[0080] Vertical cooling transformation saves gas

[0081]

[0082] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A waste heat utilization device for a chain grate rotary kiln, characterized in that: It includes a chain grate, a rotary kiln, an annular cooler, a vertical cooling kiln, a discharge assembly and a gas heat exchanger for providing heating gas to the chain grate and the rotary kiln, wherein the gas outlet of the vertical cooling kiln is connected to the gas heat exchanger for preheating the heating gas in the gas heat exchanger; Along the direction from the feed port to the discharge port, the cooling space in the ring cooler is divided into a first ring cooling section, a second ring cooling section and a third ring cooling section, and the third ring cooling section has a normal cooling mode and an emergency cooling mode; The third section of the ring cooling is in a normal cooling mode, the third section of the ring cooling is disconnected from the cooling fan providing cooling air, and the discharge port of the vertical cooling kiln is connected to the discharge assembly; The third section of the ring cooling is in an emergency cooling mode, the third section of the ring cooling is connected to a cooling fan that provides cooling air, and the discharge port of the third section of the ring cooling is connected to a discharge assembly; The discharge port of the third section of the ring cooling is connected to the feed port or the discharge assembly of the vertical cooling kiln through a chain conveyor; The chain plate machine includes a first chain plate and a second chain plate which are sequentially arranged along the direction from the discharge port of the ring cooler to the feed port of the vertical cooling kiln; the waste heat utilization device also includes a conveyor belt; the discharge end of the first chain plate is respectively connected to the feed end of the second chain plate and the feed end of the conveyor belt through a discharge direction changing component, the discharge end of the second chain plate is connected to the feed port of the vertical cooling kiln, the feed end of the conveyor belt is also connected to the discharge port of the vertical cooling kiln, and the discharge direction changing component is used for switching the discharge end of the first chain plate between a normal cooling mode and an emergency cooling mode; The material discharging redirection assembly includes a baffle and a material discharging pipe, a chain plate material inlet pipe and a conveying material inlet pipe which are interconnected. The material inlet of the material discharging pipe is connected to the material discharging end of the first chain plate, the material discharging port of the chain plate material inlet pipe is connected to the material inlet end of the second chain plate, the material discharging port of the conveying material inlet pipe is connected to the material inlet end of the conveyor belt, and one end of the baffle is rotatably connected to the inner wall of the connection area of ​​the material discharging pipe, the chain plate material inlet pipe and the conveying material inlet pipe, so that the baffle blocks the material inlet of the chain plate material inlet pipe or the material inlet of the conveying material inlet pipe; A rotary sealing valve is provided at the discharge port of the vertical cooling kiln, and the rotary sealing valve includes a plurality of windshields, which form an umbrella-shaped structure, the tip of which faces away from the vertical cooling kiln, and there is no gap between two adjacent windshields and between the windshield and the inner wall of the vertical cooling kiln. The windshield includes a fixed plate and a rotating plate, the fixed plate has an arc edge and a straight edge, the rotating plate is in the shape of a triangle, the arc edge is fixedly connected to the inner wall of the vertical cooling kiln, and the straight edge pivots with the rotating plate. When the pellets are discharged, the rotating plate rotates away from the vertical cooling kiln under the action of the pellets, and the rotating angle of the rotating plate is adjusted according to the discharge amount and discharge speed of the pellets. A return air ring is provided at the discharge port of the vertical cooling kiln. The cross-sectional shape of the return air ring along the radial direction is a semicircular arc. The return air ring is concave toward the vertical cooling kiln. When cold air leaks into the rotary kiln, the cold air is blown into the return air ring, and the flow direction of the cold air is changed through the return air ring, so that the cold air flows away from the vertical cooling kiln.

2. The waste heat utilization device for a chain grate rotary kiln according to claim 1, characterized in that: The first chain plate and the second chain plate are both inclined upward, and the discharge end of the first chain plate is located above the feed end of the second chain plate and above the feed end of the conveyor belt.

3. The waste heat utilization device for a chain grate rotary kiln according to claim 1, characterized in that: The core and / or side wall of the vertical cooling kiln are provided with an air inlet pipe.

4. The waste heat utilization device for a chain grate rotary kiln according to claim 1, characterized in that: A rotary sealing valve is provided at the discharge port of the vertical cooling kiln.

5. The waste heat utilization device for a chain grate rotary kiln according to claim 4, characterized in that: The rotary sealing valve comprises a plurality of wind shields pivoted with the inner wall of the vertical cooling kiln, wherein the plurality of wind shields form an umbrella-shaped structure, and the tip of the umbrella-shaped structure faces a direction away from the vertical cooling kiln.

6. The waste heat utilization device for chain grate rotary kiln according to claim 5, characterized in that: There is no gap between two adjacent wind shields and between a wind shield and the inner wall of the vertical cooling kiln.

7. A method for utilizing waste heat from a chain grate rotary kiln, characterized in that: Using the waste heat utilization device according to any one of claims 1 to 6, the waste heat utilization method comprises the following steps: The green balls are sequentially dried and preheated by a chain grate, sintered by a rotary kiln, and cooled for the first time by the first and second stages of a ring cooler to obtain pellets; The pellets are cooled for the second time, and the second cooling has a normal cooling mode and an emergency cooling mode. In the normal cooling mode, the vertical cooling kiln is used for the second cooling, and the third ring cooling section of the ring cooler does not provide cooling air; if the vertical cooling kiln fails, it switches to the emergency cooling mode, and only the third ring cooling section is used for the second cooling of the pellets; The air after heat exchange with the pellets in the vertical cooling kiln is used to preheat the heating gas for sintering in the rotary kiln and provide combustion air for gas combustion.

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