Low-nitrogen combustion decomposing furnace and lime calcining system

Abstract

The invention provides a low-nitrogen combustion decomposing furnace and a lime calcining system, and belongs to the technical field of limestone calcining, specifically, the low-nitrogen combustion decomposing furnace comprises a decomposing furnace body used for calcining and decomposing limestone, and a furnace chamber of the decomposing furnace body is divided into a material collecting area, a hot carbon reduction area and a combustion decomposing area; materials, combustion-supporting gas and fuel enter the decomposing furnace body in two ways, and the proportion of the materials, the combustion-supporting gas and the fuel entering the decomposing furnace body in the two ways is controlled, so that a hot carbon reduction area and a combustion decomposing area are formed in a furnace cavity of the decomposing furnace body. For example, the proportion of combustion-supporting gas in the combustion decomposition area is more, so that materials can be fully combusted, while the proportion of the combustion-supporting gas in the hot carbon reduction area can be reduced, so that insufficient combustion is carried out in the area, and meanwhile, suppression and reduction are carried out through fuel, so that nitrogen oxide passing through the area is subjected to reduction reaction to become carbon dioxide and nitrogen to be discharged; the content of nitrogen oxide is greatly reduced, and the nitrogen oxide treatment procedure of the subsequent exhaust process is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of limestone calcination, and in particular to a low-nitrogen combustion decomposition furnace and a limestone calcination system. Background Art

[0002] Currently, domestic lime calcining systems primarily utilize vertical and rotary kilns. Lumpy limestone is crushed to a suitable particle size, preheated, and calcined. The calcined limestone then decomposes into quicklime, which then needs to be cooled before storage and transportation. During the calcination process, high combustion temperatures can produce nitrogen oxides, which are harmful to both the environment and humans. Therefore, a combustion system that minimizes the production of nitrogen oxides is urgently needed. Summary of the Invention

[0003] The purpose of this application is to provide a low-nitrogen combustion decomposition furnace and a lime calcining system, aiming to solve the problem in the related art that nitrogen oxides are easily generated when the material combustion temperature is high.

[0004] Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

[0005] According to a first aspect of the present application, a low-nitrogen combustion decomposition furnace is provided, comprising: The decomposition furnace body is used to calcine and decompose limestone. The furnace cavity of the decomposition furnace body is divided into an aggregate area, a preheating decomposition area, a hot carbon reduction area, and a combustion decomposition area from bottom to top; The aggregate area is used to collect materials deposited after calcination; The preheating decomposition zone is used to heat the material; The hot carbon reduction zone is used to suppress and reduce nitrogen oxides generated during the combustion of fuel; The combustion and decomposition zone is used to calcine materials; The decomposition furnace body is provided with a first material inlet, a second material inlet, a first combustion-supporting gas inlet, a second combustion-supporting gas inlet, a first fuel inlet and a second fuel inlet, wherein the first material inlet, the first combustion-supporting gas inlet and the first fuel inlet are arranged corresponding to the preheating decomposition zone, the second material inlet and the second fuel inlet are arranged corresponding to the hot carbon reduction zone, and the second combustion-supporting gas inlet is arranged corresponding to the combustion decomposition zone; The material, combustion-supporting gas and fuel enter the decomposition furnace body in two ways, and the ratio of the material, combustion-supporting air and fuel entering the decomposition furnace body in the two ways is controlled to form a hot carbon reduction zone and a combustion decomposition zone in the furnace cavity of the decomposition furnace body.

[0006] In an exemplary embodiment of the present application, the second gas inlet is located above the hot carbon reduction zone.

[0007] In an exemplary embodiment of the present application, the first combustion-supporting gas inlet is arranged between the aggregation area and the preheating decomposition area, the position of the first fuel inlet is higher than the position of the first combustion-supporting gas inlet, and the position of the first material inlet is higher than the position of the first combustion-supporting gas inlet.

[0008] In an exemplary embodiment of the present application, a first necking structure is provided between the aggregate area and the preheating decomposition area of ​​the decomposition furnace body, the position of the first combustion-supporting gas inlet is lower than the position of the first necking structure, the position of the first fuel inlet corresponds to the first necking structure, and the position of the first material inlet is higher than the position of the first necking structure.

[0009] In an exemplary embodiment of the present application, the decomposition furnace body is further provided with a second necking structure, which is located above the second material inlet; The second fuel inlet is arranged correspondingly to the position of the second constriction structure; The positions of the second material inlet and the second combustion-supporting gas inlet are both higher than the position of the second necking structure, and the position of the second combustion-supporting gas inlet is higher than the position of the second material inlet; The preheating decomposition zone is formed between the first necking structure and the second necking structure, and the thermal carbon reduction zone and the combustion decomposition zone are sequentially formed above the second necking structure.

[0010] In an exemplary embodiment of the present application, the proportion of the upper layer of the material is 50%-90%, and the proportion of the lower layer is 10%-50%; The proportion of the combustion-supporting air in the upper layer is 50%-90%, and the proportion in the lower layer is 10%-50%; The upper layer proportion of the fuel is 50%-90%, and the lower layer proportion is 10%-50%.

[0011] In an exemplary embodiment of the present application, the combustion temperature of the combustion decomposition zone is controlled at 900°C-1000°C.

[0012] According to a second aspect of the present application, a lime calcining system is provided, comprising the above-mentioned low-nitrogen combustion decomposition furnace.

[0013] In an exemplary embodiment of the present application, a preheating unit is further included, and the preheating unit is used to preheat the material. The outlet of the preheating unit is divided into two paths and communicated with the decomposition furnace body.

[0014] In an exemplary embodiment of the present application, a cooling unit is further included, which includes a suspension cooling furnace and a separation cyclone. The suspension cooling furnace is connected to the outlet of the decomposition furnace body and is used to receive the calcined material. The separation cyclone is connected to the outlet of the suspension cooling furnace and is used to perform gas-solid separation on the cooled material. The separated gas is divided into two paths as a combustion-supporting gas and enters the decomposition furnace body.

[0015] The exemplary embodiments of the present application may have some or all of the following beneficial effects: The low-nitrogen combustion furnace provided in the exemplary embodiment of the present application includes a decomposition furnace body for calcining and decomposing limestone. The furnace cavity of the decomposition furnace body is divided into an aggregate area, a preheating decomposition area, a hot carbon reduction area, and a combustion decomposition area from bottom to top. The aggregate area is used to collect materials deposited after calcination, the preheating decomposition area is used to heat the materials, the combustion decomposition area is used to calcine the materials to calcine the limestone into lime, and the hot carbon reduction area is used to suppress and reduce nitrogen oxides generated during the combustion of the fuel. By arranging two material inlets, two combustion-supporting gas inlets, and two fuel inlets on the decomposition furnace body, the materials, combustion-supporting gas, and fuel are The gas enters the decomposition furnace body in two ways, and the ratio of the material, combustion-supporting air and fuel entering the decomposition furnace body in the two ways is controlled, so that a hot carbon reduction zone and a combustion decomposition zone are formed in the furnace cavity of the decomposition furnace body. For example, if the ratio of the combustion-supporting gas in the combustion decomposition zone is higher, the material can be fully burned, while the ratio of the combustion-supporting gas in the hot carbon reduction zone can be reduced, so that incomplete combustion occurs in this area. At the same time, the fuel is used to suppress and reduce the nitrogen oxides passing through this area, so that the nitrogen oxides are reduced to carbon dioxide and nitrogen and discharged, which greatly reduces the content of nitrogen oxides and reduces the treatment process of nitrogen oxides in the subsequent exhaust process.

[0016] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0018] Figure 1 The figure shows a schematic structural diagram of a low-nitrogen combustion decomposition furnace in Example 1 of the present application; Figure 2 The schematic diagram of the structure of the first necking structure and the second necking structure in Example 1 of the present application is shown; Figure 3The figure shows a structural diagram of the lime calcining system in Example 2 of the present application.

[0019] Description of reference numerals: 1. First-stage cyclone; 1-1. First flap valve; 1-2. Second flap valve; 2. Second-stage cyclone; 2-1. Third flap valve; 3. Third-stage cyclone; 3-1. Fourth flap valve; 4. Fourth-stage cyclone; 4-1. Fifth flap valve; 4-2. Dispensing valve; 4-3. Sixth flap valve; 4-4. Seventh flap valve; 5. Fifth-stage cyclone; 5-1. Eighth flap valve; 6. Decomposition furnace; 61. Aggregation zone; 62. Hot carbon reduction zone; 63. Combustion decomposition zone; 64. Second combustion-supporting gas inlet; 65. First combustion-supporting gas inlet; 66. First fuel inlet; 67, first material inlet; 68, second fuel inlet; 69, second material inlet; 601, first necking structure; 602, second necking structure; 603, preheating decomposition zone; 6-1 gate valve; 7, fluidized bed suspension cooling furnace; 8, separation cyclone; 8-1, ninth flap valve; 10, fluidizing fan; 11, finished product conveyor; 12, finished product warehouse; 13, high-temperature fan; 14, raw material mill; 15, fuel mill; 16, raw material warehouse; 17, multi-stage suspension preheating unit; 18, fluidized bed suspension cooling unit; 19, suspension low-nitrogen combustion unit. DETAILED DESCRIPTION

[0020] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent like or similar structures, and thus their detailed descriptions will be omitted. Furthermore, the figures are merely schematic illustrations of the present application and are not necessarily drawn to scale.

[0021] While relative terms such as "upper" and "lower" are used in this specification to describe the relationship of one illustrated component to another, these terms are used for convenience only, such as in accordance with the orientation of the illustrations in the accompanying drawings. It should be understood that if the illustrated device were flipped upside down, the component described as "upper" would become the component "lower." When a structure is referred to as "on" another structure, this may mean that the structure is integrally formed with the other structure, that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure through the other structure.

[0022] The terms "a", "an", "the" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first" and "second" are used only as labels and do not limit the quantity of their objects. Example 1

[0023] This embodiment provides a specific implementation of the low nitrogen combustion decomposition furnace 6, such as Figure 1 As shown, the calciner 6 includes a calciner for calcining and decomposing limestone. The furnace cavity of the calciner 6 is divided into a material collection area 61, a preheating decomposition area 603, a hot carbon reduction area 62 and a combustion decomposition area 63 from bottom to top. The material collection area 61 is used to collect the material deposited after calcination. The preheating decomposition area 603 is used to heat the material. The combustion decomposition area 63 is used to calcine the material (limestone). The hot carbon reduction area 63 is used to suppress and reduce nitrogen oxides generated in the preheating decomposition area 603 and the fuel during combustion. The calciner 6 is provided with a first material inlet 67, a second material inlet 69 and a first combustion-supporting gas inlet 65. , the second combustion-supporting gas inlet 64, the first fuel inlet 66 and the second fuel inlet 68, the first material inlet 67, the first combustion-supporting gas inlet 65 and the first fuel inlet 66 are arranged corresponding to the preheating decomposition zone 603, the second material inlet 69 and the second fuel inlet 68 are arranged corresponding to the hot carbon reduction zone 62, the second combustion-supporting gas inlet 64 is arranged corresponding to the combustion decomposition zone 63, the material, combustion-supporting gas and fuel are divided into two routes to enter the decomposition furnace 6 body, and the ratio of the material, combustion-supporting gas and fuel entering the decomposition furnace 6 body through the two routes is controlled so that a hot carbon reduction zone 62 and a combustion decomposition zone 63 are formed in the furnace cavity of the decomposition furnace 6 body.

[0024] Furthermore, in the combustion decomposition zone 63, the proportion of combustion-supporting gas is higher and the proportion of fuel and material is lower, so that the material can be fully burned, while in the preheating decomposition zone 603, the proportion of combustion-supporting gas is lower and the proportion of material and fuel is higher. Incomplete combustion of the fuel will produce carbon monoxide, which will increase the combustion temperature of the material. As the material and fuel rise to the hot carbon reduction zone, the combustion-supporting gas is consumed, and the nitrogen oxides produced in the preheating decomposition zone 603 are reduced here, converting the nitrogen oxides into carbon dioxide and nitrogen, reducing the subsequent process of exhaust gas treatment and reducing pollution to the environment; when the material rises to the combustion decomposition zone 63, the high proportion of combustion-supporting gas can enable the material to be fully burned.

[0025] In this embodiment, the second gas inlet is located above the hot carbon reduction zone 62. When the combustion-supporting gas is introduced into the second gas inlet, a combustion decomposition zone 63 is formed above the hot carbon reduction zone 62. Most of the combustion-supporting gas entering from the second gas inlet is in the combustion decomposition zone 63 above the hot carbon reduction zone 62. When the material and fuel flow upward under the influence of the airflow, the material and fuel will be fully burned and exhausted after passing through the combustion decomposition zone, thereby avoiding the outflow of unburned material and fuel.

[0026] In this embodiment, the first combustion-supporting gas inlet 65 is arranged between the aggregation area 61 and the preheating decomposition area 603, the position of the first fuel inlet 66 is higher than the position of the first combustion-supporting gas inlet 65, and the position of the first material inlet 67 is higher than the position of the first combustion-supporting gas inlet 65. This design allows the combustion gas to enter from the first combustion-supporting gas inlet 65 and flow upward, driving the fuel and material above to mix and burn, and avoiding the material and fuel entering from below the first combustion-supporting gas inlet 65, which is inconvenient to use the flow of combustion-supporting gas for sufficient mixing.

[0027] Furthermore, a first necking structure 601 is provided between the aggregate area 61 and the preheating decomposition area 603 of the decomposition furnace 6 body. The position of the first combustion-supporting gas inlet 65 is lower than the position of the first necking structure 601, the position of the first fuel inlet 66 corresponds to the first necking structure 601, and the position of the first material inlet 67 is higher than the position of the first necking structure 601. When the combustion-supporting gas enters from the first combustion-supporting gas inlet 65, it flows upward through the first necking structure 601, which will change the flow rate to form turbulence, thereby accelerating the mixing of the fuel and the material. The first fuel inlet 66 is set at the position of the first necking structure 601. Since the flow rate of the combustion-supporting gas is faster at the first necking structure 601, the fuel can be quickly mixed with the material above.

[0028] In this embodiment, a second necking structure 602 is provided on the decomposition furnace 6 body, which is located above the second material inlet 69. The second fuel inlet 68 is arranged corresponding to the position of the second necking structure 602. The positions of the second material inlet 69 and the second combustion-supporting gas inlet 64 are both higher than the position of the second necking structure 602, and the position of the second combustion-supporting gas inlet 64 is higher than the position of the second material inlet 69. A hot carbon reduction zone 62 is formed between the first necking structure 601 and the second necking structure 602, and a combustion decomposition zone 63 is formed above the second necking structure 602.

[0029] In this embodiment, the proportion of the material in the upper layer of the furnace chamber of the decomposition furnace 6 is 50%-90%, and the proportion in the lower layer is 10%-50%; the proportion of the combustion-supporting gas in the upper layer is 50%-90%, and the proportion in the lower layer is 10%-50%; and the proportion of the fuel in the upper layer is 50%-90%, and the proportion in the lower layer is 10%-50%. The proportions of the material, combustion-supporting gas, and fuel in the lower thermal carbon reduction zone 62 and the upper combustion decomposition zone 63 are controlled to achieve sufficient combustion of the material and minimize the elimination of nitrogen oxides.

[0030] In this embodiment, the combustion temperature of the combustion decomposition zone 63 is controlled between 900° C. and 1000° C. to avoid the generation of excessive thermal nitrogen oxides.

[0031] In this embodiment, the material is limestone, which becomes slaked lime after being calcined in the decomposition furnace 6; the fuel is pulverized coal, which can more quickly burn and decompose the limestone by adding pulverized coal. At the same time, the pulverized coal can also inhibit and reduce the generated nitrogen oxides.

[0032] In this embodiment, the combustion-supporting gas is air, and the air is introduced to provide oxygen for the calcination of the decomposition furnace 6 .

[0033] In this embodiment, Figure 2 As shown, the ratio of the first constricted structure 601 to the second constricted structure 602 is: d / D is 0.5-0.9, and h / H is 0-0.5, wherein the first fuel inlet 66 and the second fuel inlet 68 are both arranged at constricted positions. Example 2

[0034] This embodiment provides a specific implementation method of a lime calcining system, including the low-nitrogen calcining decomposition furnace 6 in Example 1, and also includes a preheating unit, which is used to preheat the material to reduce the heating time of the low-nitrogen calcining decomposition furnace 6. The outlet of the preheating unit is divided into two routes and connected to the decomposition furnace 6 body, and the two routes are respectively connected to the first material inlet 67 and the second material inlet 69.

[0035] In this embodiment, a cooling unit is also included, which includes a suspension cooling furnace and a separation cyclone 8. The suspension cooling furnace is connected to the outlet of the decomposition furnace 6 and is used to receive the calcined material. The separation cyclone 8 is connected to the outlet of the suspension cooling furnace and is used to perform gas-solid separation on the cooled material. The separated gas is divided into two paths as a combustion-supporting gas and enters the decomposition furnace 6, namely the first combustion-supporting gas inlet 65 and the second combustion-supporting gas inlet 64. At this time, the combustion-supporting gas has just completed heat exchange with the material and has a certain temperature itself, which further reduces the heating time of the decomposition furnace 6 and improves the calcination efficiency of the material.

[0036] like Figure 3As shown, it includes a multi-stage suspension preheating unit 17, a suspension low-nitrogen combustion unit 19, and a fluidized bed suspension cooling unit 18, wherein the multi-stage suspension preheating unit 17 includes a plurality of cyclones connected by connecting pipes; the suspension low-nitrogen combustion unit 19 includes a decomposition furnace 6 body, which is connected to the cyclones in the multi-stage suspension preheating unit 17, and the decomposition furnace 6 body is used to receive materials transported from the cyclones; the fluidized bed suspension cooling unit 18 includes a fluidized bed suspension cooling furnace 7 and two separation cyclones 8 arranged in parallel, the fluidized bed suspension cooling furnace 7 is used to receive and cool the materials after combustion in the decomposition furnace 6 body and then gas-solid separation in the cyclones, and the two separation cyclones 8 arranged in parallel are used to perform gas-solid separation on the materials cooled by the fluidized bed suspension cooling furnace 7 for storage or transportation to the finished product warehouse 12.

[0037] In this application, two parallel cyclones are set in the cooling unit to perform single-stage gas-solid separation. The cooled material only needs to pass through one of the separation cyclones 8 to complete the separation, which greatly reduces the operating resistance of the system, reduces power consumption, and thus reduces costs. The two parallel separation cyclones 8 reduce the operating resistance of the system while meeting the separation efficiency. In this application, the fluidized bed suspension cooling furnace 7 can receive the material separated by the terminal cyclone and cool the material. During the cooling process, cold air enters the fluidized bed suspension cooling furnace 7, mixes with the material and undergoes heat exchange to reduce the temperature of the material. The fully mixed material and cold air enter the separation cyclone 8 for further heat exchange and gas-solid separation. The material separated in the separation cyclone 8 is the finished product and can be used for storage and transportation. The cold air enters from the bottom of the fluidized bed suspension cooling furnace 7 and flows from bottom to top. During the upward flow, it mixes with the material and drives the material upward, ultimately carrying the material into the separation cyclone 8 for gas-solid separation.

[0038] The high-temperature fan 13 is connected to the first-stage cyclone 1 in the multi-stage suspension preheating unit 17. The high-temperature fan 13 is used to extract hot air flowing through the fluidized bed suspension cooling unit 18, the suspension low-nitrogen combustion unit 19, and the multi-stage suspension preheating unit 17, so that the hot air in the system is discharged from the combustion cooling part after passing through the multi-stage suspension preheating unit 17. During the process of conveying the material from the multi-stage suspension preheating unit 17 to the suspension low-nitrogen combustion unit 19, it first exchanges heat with the hot air to complete preheating. The material has a certain temperature when entering the suspension low-nitrogen combustion unit 19, thereby reducing the heating time of the material in the suspension low-nitrogen combustion unit 19. The fuel mill 15 is used to convey fuel to the decomposition furnace 6. Only after the fuel is conveyed, the material in the decomposition furnace 6 can be calcined. The raw material mill 14 is used to provide material to the raw material silo 16. The raw material silo 16 is connected to the multi-stage suspension preheating unit 17, and the material is conveyed to the multi-stage suspension preheating unit 17 through the raw material silo 16. The finished product silo 12 is used to receive the finished product material after being cooled by the separation cyclone 8.

[0039] In this embodiment, the multi-stage suspension preheating unit 17 includes a first-stage cyclone 1, a second-stage cyclone 2, a third-stage cyclone 3, a fourth-stage cyclone 4 and a fifth-stage cyclone 5. The high-temperature fan 13 is connected to the first-stage cyclone 1, and the inlet of the first-stage cyclone 1 is connected to the raw material storage 16. A first connecting air duct is provided between the inlet of the first-stage cyclone 1 and the inlet of the second-stage cyclone 2, a second connecting air duct is provided between the inlet of the second-stage cyclone 2 and the inlet of the third-stage cyclone 3, and a second connecting air duct is provided between the inlet of the third-stage cyclone 3 and the inlet of the fourth-stage cyclone 4. A fourth connecting air duct is provided between the third connecting air duct, the inlet of the fourth-stage cyclone 4 and the inlet of the fifth-stage cyclone 5. The outlet of the first-stage cyclone 1 and the second connecting air duct, the outlet of the second-stage cyclone 2 and the third connecting air duct, and the outlet of the third-stage cyclone 3 and the fourth connecting air duct are connected through a material pipeline. The outlet of the fifth-stage cyclone 5 is connected to the fluidized bed suspension cooling furnace 7, the outlet of the fourth-stage cyclone 4 is connected to the material inlet of the decomposition furnace 6, and the inlet of the fifth-stage cyclone 5 is connected to the material outlet on the upper part of the decomposition furnace 6.

[0040] The material conveying process is as follows: the material in the raw material warehouse 16 enters the first-stage cyclone 1 through the first connecting air duct. During the material conveying process in the first connecting air duct, the material is heat exchanged with the gas, and the material is brought into the first-stage cyclone 1 by the air flow for gas-solid separation; the separated material enters the third-stage cyclone 3 to the second-stage cyclone 2 in the second connecting air duct for material-gas heat exchange, and the material is brought into the second-stage cyclone 2 by the air flow for gas-solid separation; the separated material enters the fourth-stage cyclone 4 to the third-stage cyclone 3 in the third connecting air duct for material-gas heat exchange, and the material is brought into the second-stage cyclone 2 by the air flow for gas-solid separation. The separated material enters the third-stage cyclone 3 for gas-solid separation. The separated material enters the fourth connecting air duct from the fifth-stage cyclone 5 to the fourth-stage cyclone 4 for material-gas heat exchange, after which it is brought into the fourth-stage cyclone 4 for gas-solid separation. The separated material enters the decomposition furnace 6, where it is calcined and decomposed. The decomposed material is divided into two paths: one path follows the rising airflow into the fifth-stage cyclone 5, where it is separated and then enters the fluidized bed suspension cooling furnace 7; the other path settles to the bottom of the decomposition furnace 6 and then enters the fluidized bed suspension cooling furnace 7. The material passes through the multi-stage suspension preheating unit 17 before entering the decomposition furnace 6, which can pre-raise the material temperature and shorten the calcination time in the decomposition furnace 6.

[0041] In this embodiment, a fluidizing fan 10 is further included. The outlet of the fluidizing fan 10 is connected to the fluidized bed suspension cooling furnace 7, and the connection position of the fluidizing fan 10 and the fluidized bed suspension cooling furnace 7 is lower than the connection position of the five-stage cyclone 5 and the decomposition furnace 6 and the fluidized bed suspension cooling furnace 7. That is, the connection position of the fluidizing fan 10 and the fluidized bed suspension cooling furnace 7 is located at the bottom of the fluidized bed suspension cooling furnace 7, so that air can move upward from the bottom of the fluidized bed suspension cooling furnace 7, so that the material is in a suspended fluidized state in the fluidized bed suspension cooling furnace 7. , gas-solid heat exchange is carried out. The heated air flow enters the parallel-arranged separation cyclone 8 from the furnace top for gas-solid separation. The hot gas enters the decomposition furnace 6 body in two ways, upper and lower, as combustion-supporting air. The flue gas generated in the material decomposition furnace 6 body enters the multi-stage suspension preheating unit 17 from the top of the decomposition furnace 6 body in sequence. The flue gas from the first-stage cyclone 1 is used as a drying heat source and enters the raw material mill 14 and the fuel mill 15 respectively through the high-temperature fan 13. The material exiting the outlet of the separation cyclone 8 is the finished material and is stored or transported to the finished product warehouse 12. At the same time, the inlet of the fluidizing fan 10 is arranged at the bottom of the fluidized bed suspension cooling furnace 7 to avoid material collapse. The fluidizing fan 10 blows air upward from the bottom of the fluidized bed suspension cooling furnace 7 to prevent material from accumulating at the bottom of the fluidized bed suspension cooling furnace 7.

[0042] In this embodiment, a high-temperature fan 13 is further included. The high-temperature fan 13 is connected to the outlet of the first-stage cyclone 1. The extraction of the high-temperature fan 13 causes the cyclones in the multi-stage suspension preheating unit 17 to be in a negative pressure state, and the outlet of the high-temperature fan 13 can also be connected to the raw material mill 14 and the fuel mill 15. The hot gas blown out by the high-temperature fan 13 can be used to preheat the raw material mill 14 and the fuel mill 15.

[0043] In this embodiment, the materials separated from the four-stage cyclone 4 enter the decomposition furnace 6 in two ways. The materials are distributed in the decomposition furnace 6 in two layers, with the upper layer accounting for 50%-90% and the lower layer accounting for 10%-50%. Furthermore, an upper combustion decomposition zone 63 and a lower hot carbon reduction zone 62 are formed in the decomposition furnace 6 body; wherein, the distribution ratio of the upper combustion-supporting air in the decomposition furnace 6 body is 50%-90%, and the distribution ratio of the lower combustion-supporting air is 10%-50%; the distribution ratio of the upper fuel in the decomposition furnace 6 body is 50%-90%, and the distribution ratio of the lower fuel is 10%-50%. Through the proportional distribution of different materials, combustion-supporting air and fuel in the upper and lower layers, an upper combustion decomposition zone 63 and a lower hot carbon reduction zone 62 are formed in the decomposition furnace 6 body. If there is more material in the lower layer of the decomposition furnace 6 body and less combustion-supporting air and fuel, the material is not fully burned, and the lower hot carbon reduction zone 62 is formed, and a reduction reaction occurs, so that most of the NOx generated by the fuel reacts with CO in the reduction zone to become N2 and CO2. When there is more material in the upper layer of the decomposition furnace 6 body and more combustion-supporting air and fuel, the material is fully burned, forming a combustion decomposition zone 63.

[0044] Furthermore, the combustion decomposition zone 63 is a heat-concentrated release zone. Adding materials to this zone can absorb heat and balance the temperature, so that the temperature is stably controlled at 900-1000°C, avoiding the generation of excessive thermal nitrogen oxides. By controlling the temperature within this zone, the limestone can be completely decomposed into lime (CaO) without excessively burning the lime into dead lime (lime calcined at a temperature above 1100°C). The unburned coal powder is ensured to be burned out by adding combustion-supporting air in the upper combustion decomposition zone 63.

[0045] In this embodiment, both the calciner 6 and the fluidized bed suspension cooling furnace 7 are equipped with a central constriction structure to create a gushing effect. When the material and fuel pass through the central constriction structure, the airflow velocity suddenly increases and the pressure changes, resulting in strong turbulence and mixing, which prevents laminar flow and promotes the full dispersion, mixing, and combustion of the material and fuel. Furthermore, the inlet of the fuel mill 15 on the calciner 6 is located at the constriction structure. Due to the limited space in the calciner 6, the fuel inlet is located at the constriction structure, which allows the fuel to be more dispersed upon entering the calciner 6. The airflow velocity increases at the central constriction structure, allowing for rapid fuel dispersion and combustion. Furthermore, the fuel mill 15 enters the calciner 6 in two ways, one above and one below, to prevent fuel from accumulating in the calciner 6. This dual entry reduces fuel accumulation, accelerates the mixing of fuel and material, and speeds up the fuel's combustion rate.

[0046] Furthermore, a plurality of middle necking structures are provided at different positions in the furnace, so that a gushing effect can be formed at multiple positions in the furnace.

[0047] Furthermore, the outlet of the high-temperature fan 13 is connected to the raw material mill 14 and the fuel mill 15, so that the flue gas extracted from the first-stage cyclone 1 by the high-temperature air can be transported to the raw material mill 14 and the fuel mill 15 as a drying heat source to heat the material and fuel respectively.

[0048] In this embodiment, the fuel provided by the fuel mill 15 is pulverized coal. Of course, other fuels besides pulverized coal can also be selected as long as it does not affect the overall structure and process flow.

[0049] In this embodiment, the separation cyclone 8 is connected to the lower hot carbon reduction zone 62 and the upper combustion decomposition zone 63 of the decomposition furnace 6 body through connecting pipes, and a gate valve 6-1 is provided on the connecting pipes. By controlling the gate valve 6-1, the amount of combustion-supporting air delivered by the separation cyclone 8 to the decomposition furnace 6 body can be controlled separately, so that the proportional distribution of combustion-supporting air in the decomposition furnace 6 body can meet the proportional distribution of the upper combustion decomposition zone 63 and the lower hot carbon reduction zone 62.

[0050] Furthermore, the separation cyclone 8 can transfer the hot air after heat exchange, and the combustion air used by the decomposition furnace 6 does not come from the cold air in the atmosphere. Moreover, the heat of the high-temperature lime entering the cooling furnace after separation by the five-stage cyclone 5 is cooled by the fluidized bed suspension cooling furnace 7. Almost all of the heat is taken away by the air entering the separation cyclone 8, which not only heats the air required for coal combustion in the calcining furnace and saves coal, but also quickly cools the high-temperature lime brought by the five-stage cyclone 5, making it easier to store and transport.

[0051] In this embodiment, the first-stage cyclone 1 is composed of two cyclones arranged side by side, and a flap valve is provided between each cyclone and the third-stage cyclone 3, namely the first flap valve 1-1 and the second flap valve 1-2; a third flap valve 2-1 is provided between the second-stage cyclone 2 and the four-season cyclone; a fourth flap valve 3-1 is provided between the third-stage cyclone 3 and the fifth-stage cyclone 5; the fourth-stage cyclone 4 and the decomposition furnace 6 are connected through a dividing valve 4-2, and the dividing valve 4-2 divides the material into two paths to enter the decomposition furnace 6, a fifth flap valve 4-1 is provided between the fourth-stage cyclone 4 and the dividing valve 4-2, and a sixth flap valve 4-3 and a seventh flap valve 4-4 are provided between the dividing valve 4-2 and the decomposition furnace 6 respectively; an eighth flap valve 5-1 is provided between the fifth-stage cyclone 5 and the fluidized bed suspension cooling furnace 7.

[0052] In this embodiment, the separation cyclone 8 is connected to the finished product conveyor 11. After the finished material comes out of the separation cyclone 8, it is transported to the finished product warehouse 12 by the finished product conveyor 11. A ninth flap valve 8-1 is provided between the two separation cyclones 8 and the finished product conveyor 11.

[0053] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the embodiments of the present invention. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not covered by this application. The specification and embodiments are intended to be exemplary only, and the true scope and spirit of the present invention are indicated by the appended claims.

Claims

1. A low nitrogen combustion decomposition furnace, characterized in that: include: The decomposition furnace body is used to calcine and decompose limestone. The furnace cavity of the decomposition furnace body is divided into an aggregate area, a preheating decomposition area, a hot carbon reduction area, and a combustion decomposition area from bottom to top; The aggregate area is used to collect materials deposited after calcination; The preheating decomposition zone is used to heat the material; The hot carbon reduction zone is used to suppress and reduce nitrogen oxides generated in the preheat decomposition zone and during the combustion of the fuel; The combustion and decomposition zone is used to calcine materials; The decomposition furnace body is provided with a first material inlet, a second material inlet, a first combustion-supporting gas inlet, a second combustion-supporting gas inlet, a first fuel inlet and a second fuel inlet, wherein the first material inlet, the first combustion-supporting gas inlet and the first fuel inlet are arranged corresponding to the preheating decomposition zone, the second material inlet and the second fuel inlet are arranged corresponding to the hot carbon reduction zone, and the second combustion-supporting gas inlet is arranged corresponding to the combustion decomposition zone; The material, combustion-supporting gas and fuel enter the decomposition furnace body in two ways, and the ratio of the material, combustion-supporting air and fuel entering the decomposition furnace body in the two ways is controlled to form a hot carbon reduction zone and a combustion decomposition zone in the furnace cavity of the decomposition furnace body.

2. The low nitrogen combustion decomposition furnace according to claim 1, characterized in that: The second gas inlet is located above the hot carbon reduction zone.

3. The low nitrogen combustion decomposition furnace according to claim 2, characterized in that: The first combustion-supporting gas inlet is arranged between the aggregate zone and the preheating decomposition zone, the first fuel inlet is located higher than the first combustion-supporting gas inlet, and the first material inlet is located higher than the first combustion-supporting gas inlet.

4. The low nitrogen combustion decomposition furnace according to claim 3, characterized in that: A first necking structure is provided between the aggregation area and the preheating decomposition area of ​​the decomposition furnace body. The position of the first combustion-supporting gas inlet is lower than the position of the first necking structure. The position of the first fuel inlet corresponds to the first necking structure. The position of the first material inlet is higher than the position of the first necking structure.

5. The low nitrogen combustion decomposition furnace according to claim 4, characterized in that: The decomposition furnace body is further provided with a second constriction structure, which is located above the second material inlet; The second fuel inlet is arranged correspondingly to the position of the second constriction structure; The positions of the second material inlet and the second combustion-supporting gas inlet are both higher than the position of the second necking structure, and the position of the second combustion-supporting gas inlet is higher than the position of the second material inlet; The preheating decomposition zone is formed between the first necking structure and the second necking structure, and the thermal carbon reduction zone and the combustion decomposition zone are sequentially formed above the second necking structure.

6. The low nitrogen combustion decomposition furnace according to claim 1, characterized in that: The upper layer proportion of the material is 50%-90%, and the lower layer proportion is 10%-50%; The proportion of the combustion-supporting air in the upper layer is 50%-90%, and the proportion in the lower layer is 10%-50%; The upper layer proportion of the fuel is 50%-90%, and the lower layer proportion is 10%-50%.

7. The low nitrogen combustion decomposition furnace according to claim 1, characterized in that: The combustion temperature of the combustion decomposition zone is controlled at 900°C-1000°C.

8. A lime calcining system, characterized in that: The invention comprises the low-nitrogen combustion decomposition furnace according to any one of claims 1 to 7.

9. The lime calcining system according to claim 8, characterized in that: It also includes a preheating unit, which is used to preheat the material. The outlet of the preheating unit is divided into two paths and communicates with the decomposition furnace body.

10. The lime calcining system according to claim 8, characterized in that: It also includes a cooling unit, which includes a suspended cooling furnace and a separation cyclone. The suspended cooling furnace is connected to the outlet of the decomposition furnace body and is used to receive the calcined material. The separation cyclone is connected to the outlet of the suspended cooling furnace and is used to perform gas-solid separation on the cooled material. The separated gas is divided into two paths as a combustion-supporting gas and enters the decomposition furnace body.

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