Blast furnace coal injection raw coal online preheating method and system

Abstract

The invention discloses a blast furnace coal injection raw coal online preheating method and system, relates to the technical field of blast furnace ironmaking coal injection, and aims to solve the problem that raw coal of a pulverized coal preparation system needs a better preheating dehydration scheme. The method comprises the steps that a raw coal bunker is transformed or newly built, multiple layers of steam pipelines are arranged in the height direction of a bunker body, the two ends of the multiple layers of steam pipelines are connected to the same main steam pipeline, and all the layers of steam pipelines penetrate through the wall of the raw coal bunker and are connected with a heat exchange structure in the bunker; an anti-collision device is additionally arranged above each layer of steam pipeline and the heat exchange structure in the bin to play a role in protection, and a drain pipe is connected below the outlet end of each layer of steam pipeline to drain condensate water; the top of the raw coal bunker is connected with a dust remover for discharging water vapor generated after raw coal is heated; the structure is simple, and the preheating effect on raw coal is effectively improved; the water content of the preheated raw coal entering the mill is reduced, and the yield of the mill can be effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of coal injection for blast furnace ironmaking, and in particular to an online preheating method and system for coal injection for blast furnace. Background Art

[0002] Blast furnace coal injection technology is one of the main process technologies in the modern blast furnace ironmaking process system. The main function of coal powder injected into the blast furnace is to replace part of the coke in the blast furnace, provide part of the heat source and reducing agent for blast furnace ironmaking, so as to reduce the coke ratio and reduce the cost of ironmaking. In actual production, some steel enterprises and coal-using enterprises have to use some low-priced and poorer quality raw coal (including high moisture content) in order to further reduce costs, which seriously affects the output of the coal mill and leads to insufficient capacity for the preparation of the entire coal powder. At the same time, in order to meet the normal production of the blast furnace, the mill operation rate is almost 100%, and there is no time for maintenance, which brings certain safety risks to the normal production of the blast furnace; another part of the enterprises, in order to reduce inventory and reduce financial pressure, directly use the raw coal for powder making after purchasing it, and there is no time to carry out the stacking and drying operation in the raw coal yard, which makes the raw coal entering the mill, especially the moisture content, high, which also affects the output of the mill. In addition, there are also environmental factors, such as rainy days and open-air storage, which will cause the moisture content of the raw coal entering the mill to be higher, which is not conducive to the preparation and production of coal powder.

[0003] Theoretical calculations and practical results show that when the moisture content of raw coal is above 10%, the output of mill pulverized coal can be increased by 1.1-1.4% if the moisture content is reduced by 1%. Therefore, reducing the moisture content of raw coal is very beneficial to pulverized coal preparation.

[0004] At present, few enterprises preheat and dehydrate raw coal. Even if some enterprises do, the process is relatively complex, the investment and operation cost is high, and the overall economic benefits are not obvious. For example, in other industries such as cement, some use drying furnace process, drum furnace process, electric heating process, etc., but in the pulverized coal preparation process of blast furnace coal injection, the application of relevant preheating and dehydration process has not been seen. Therefore, an online preheating method and system for raw coal injection in blast furnace is urgently needed to solve this problem. Summary of the invention

[0005] The object of the present invention is to provide a method and system for online preheating of raw coal for blast furnace coal injection, so as to solve the problem that the raw coal of the pulverized coal preparation system needs a better preheating and dehydration scheme.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a method for online preheating of raw coal for coal injection in a blast furnace, comprising the following steps: modifying or newly building a raw coal bunker, arranging a plurality of layers of steam pipes in the direction of the bunker height, connecting both ends of the plurality of layers of steam pipes to the same main steam pipeline, and passing through the wall of the raw coal bunker respectively, and connecting to a heat exchange structure in the bunker, installing an anti-collision device above each layer of steam pipes and the heat exchange structure in the bunker for protection, connecting a drain pipe below the outlet end of each layer of steam pipes for discharging condensed water; and connecting a dust collector on the top of the raw coal bunker for discharging water vapor generated after the raw coal is heated.

[0007] Another technical solution provided by the present invention is: an online preheating system for raw coal for coal injection in a blast furnace, comprising a raw coal bunker, a steam main pipe and an outlet main pipe are arranged on the outside of the raw coal bunker, a plurality of steam branch pipes are connected between the two, each steam branch pipe penetrates into the raw coal bunker at different heights, and passes out of the raw coal bunker after a heat exchange structure is arranged on a horizontal plane at the height, each steam branch pipe is also connected to a steam branch pipe drain pipe at the point where it passes through the raw coal bunker, and a steam trap is connected to the outlet main pipe and each steam branch pipe drain pipe respectively; a steam branch pipe anti-collision device is fixedly provided above each steam branch pipe inside the raw coal bunker for preventing impact and friction on the steam branch pipe during the falling process of the raw coal.

[0008] Preferably, a steam branch pipe inlet valve and a steam branch pipe outlet valve are respectively provided at both ends of the steam branch pipe, and a steam main pipe valve is provided at the front end of all the steam branch pipes.

[0009] Preferably, the outlet main pipe and each steam branch pipe drain pipe are also respectively connected to a plurality of valve components, including a first steam trap, wherein the first steam trap on the steam branch pipe drain pipe is located close to one end of each steam branch pipe drain pipe connected to each steam branch pipe, and the first steam trap on the outlet main pipe is located at the rear end of all steam branches; the valve components also include a second steam trap located at the inlet end of each steam trap and a fourth steam trap located at the outlet end of the steam trap, a bypass pipeline is connected between the inlet end of the second steam trap and the outlet end of the fourth steam trap, and a third steam trap is provided on the bypass pipeline.

[0010] Preferably, the heat exchange structure is a U-shaped coil, which includes a plurality of parallel straight pipe sections and connecting sections at the ends of the straight pipe sections, wherein the spacing between adjacent straight pipe sections is equal, and the connecting sections are alternately distributed at both ends of the straight pipe sections.

[0011] Preferably, the steam branch anti-collision device has two connected inclined surfaces, which are respectively located above the two sides of the steam branch, and the inclined direction is from the upper middle part of the steam branch to the upper parts of the two sides obliquely downward.

[0012] Preferably, the steam branch pipe anti-collision device is fixedly connected to the inner wall of the raw coal bunker, and a plurality of hanging points are fixedly arranged at intervals at the lower end of the steam branch pipe anti-collision device for hanging and supporting the steam branch pipe.

[0013] Preferably, a raw coal bunker top dust collector is fixedly provided on the top of the raw coal bunker, and a dust removal fan is provided inside the raw coal bunker for discharging water vapor generated after the raw coal is heated.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The online preheating method and system for blast furnace coal injection raw coal adopts a multi-layer heat exchange structure arrangement, which effectively increases the preheating effect of the raw coal and preheats and dehydrates the raw coal before entering the mill. On the one hand, it can improve the smoothness of the raw coal before entering the mill and reduce the occurrence of blockage. On the other hand, due to the increase in the temperature of the raw coal, part of the water in it is evaporated, which can effectively reduce the water content of the raw coal, reduce the workload of the mill, reduce the equipment operation rate, and improve the output level of the mill. It can effectively increase the output of the mill and give full play to the maximum capacity of the equipment.

[0016] 2. The online preheating method and system for blast furnace coal injection raw coal has a simple structure for new construction or renovation, has little impact on the storage capacity of the raw coal bunker, saves investment, and has good controllability during operation. At the same time, the preheating system discharges water vapor during operation, which is environmentally friendly. In addition, the preheating medium in the present invention is steam, which can be saturated steam or supersaturated steam, both of which are common media in the factory area. Generally, enterprises have a large amount of surplus steam, which can be fully utilized, which is a measure for energy saving. The water vapor in the raw coal preheating process is discharged out of the bunker through the dust collector set on the bunker roof, which can effectively improve the bunker roof working environment, and the dust collector on the raw coal bunker roof can directly use the original dust removal equipment without adding new ones. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention, in which only two layers of heat exchange structures are drawn for illustration;

[0018] Figure 2 It is a schematic cross-sectional structure diagram of the steam branch pipe anti-collision device of the present invention;

[0019] Figure 3 The figure is a schematic diagram of the positional relationship between the steam branch pipe anti-collision device and the steam branch pipe of the present invention.

[0020] In the figure: 1. Steam main pipe; 1.1. Steam branch pipe inlet valve; 1.2. Steam branch pipe outlet valve; 1.3. Steam branch pipe; 1.4.1. First steam trap; 1.4.2. Second steam trap; 1.4.3. Third steam trap; 1.4.4. Fourth steam trap; 1.5. Steam branch pipe drain pipe; 1.6. Steam branch pipe anti-collision device; 2. Steam main pipe valve; 3.1. Steam trap; 4. Outlet main pipe; 6. Dust collector on the top of raw coal bunker. DETAILED DESCRIPTION

[0021] In view of the fact that the preheating and dehydration treatment of raw coal has a more obvious effect on improving the mill output of the coal powder preparation system, and taking into account the economic benefits and the difficulty of specific implementation, the present invention aims to propose an online preheating method for blast furnace coal injection that is relatively low in investment, simple to implement, and convenient in production and maintenance. The method specifically comprises: renovating or building a raw coal bunker, arranging multiple layers of steam pipes in the height direction of the bunker body, connecting the two ends of the multiple layers of steam pipes to the same main steam pipeline respectively, and each layer of steam pipes passes through the wall of the raw coal bunker respectively, and is connected to a heat exchange structure in the bunker, and anti-collision devices are installed above the steam pipes and heat exchange structures on each layer in the bunker for protection, and a drain pipe is connected below the outlet end of each layer of steam pipes to discharge condensed water; a dust collector is connected to the top of the raw coal bunker to discharge water vapor generated after the raw coal is heated.

[0022] To implement the above method, the present invention provides the following preheating system, see Figures 1 to 3 , including a raw coal bunker, with a steam main pipe 1 and an outlet main pipe 4 on the outside, and multiple steam branch pipes 1.3 connected between the two, each steam branch pipe 1.3 penetrates into the raw coal bunker at different heights, and passes out of the raw coal bunker after arranging a heat exchange structure on the horizontal plane at the height, each steam branch pipe 1.3 is also connected to a steam branch pipe drain pipe 1.5 at the place where it passes out of the raw coal bunker, and the outlet main pipe 4 and each steam branch pipe drain pipe 1.5 are respectively connected to a steam trap 3.1, which is used to discharge the water condensed in the pipe after the heat exchange steam; considering the problem that the steam pipe in the raw coal bunker is directly squeezed and rubbed by the gravity of the coal seam, causing the pipe to deform and crack, and finally causing steam to leak into the raw coal bunker, a steam branch pipe anti-collision device 1.6 is fixedly provided above each steam branch pipe 1.3 inside the raw coal bunker, which is used to prevent the impact and friction on the steam branch pipe 1.3 during the falling process of the raw coal. In the above structure, without affecting the downward movement of the raw coal, the height direction spacing of adjacent heat exchange structures can be set according to actual conditions.

[0023] In addition, the inlet end of the steam main pipe 1 can be connected to the steam main of the factory area, and the outlet ends of the outlet main pipe 4 and each steam branch drainage pipe 1.5 can be connected to the drainage ditch around the factory building; the coal inlet at the upper end of the raw coal bunker is generally provided with a belt conveyor to continuously transport the raw coal into the raw coal bunker.

[0024] Optionally, a steam branch pipe inlet valve 1.1 and a steam branch pipe outlet valve 1.2 are respectively provided at both ends of the steam branch pipe 1.3, and whether the steam pipes on each layer are connected to the preheating system can be adjusted on site according to actual needs; the steam main pipe 1 is located at the front end of all steam branch pipes 1.3 and is provided with a steam main pipe valve 2, which is used to select whether to start the steam preheating system and daily inspection and maintenance according to the actual situation of the raw coal bunker.

[0025] To ensure drainage and facilitate valve maintenance, the outlet main pipe 4 and each steam branch pipe drainage pipe 1.5 are optionally connected with a plurality of valve components, including a first steam trap 1.4.1, wherein the first steam trap 1.4.1 on the steam branch pipe drainage pipe 1.5 is located close to one end of each steam branch pipe drainage pipe 1.5 connected to each steam branch pipe 1.3, and the first steam trap 1.4.1 on the outlet main pipe 4 is located at the rear end of all steam branch pipes 1.3; the valve components also include a second steam trap 1.4.2 located at the inlet end of each steam trap 3.1 and a fourth steam trap 1.4.4 located at the outlet end of the steam trap 3.1, a bypass pipeline is connected between the inlet end of the second steam trap 1.4.2 and the outlet end of the fourth steam trap 1.4.4, and a third steam trap 1.4.3 is arranged on the bypass pipeline. When working normally, the third steam trap 1.4.3 is closed, and the first steam trap 1.4.1, the second steam trap 1.4.2 and the fourth steam trap 1.4.4 are opened.

[0026] In a preferred embodiment, the heat exchange structure is a U-shaped coil, which includes a plurality of parallel straight pipe sections and connecting sections at the ends of the straight pipe sections, wherein the spacing between adjacent straight pipe sections is equal (e.g. Figure 1 As shown in FIG. 1 , the connection sections are alternately distributed at both ends of the straight pipe section. This structure is more suitable. When the steam passes through the steam branch pipe 1.3 and bypasses the warehouse, its heat is transferred to the raw coal around it through the pipe wall of the steam branch pipe 1.3 to heat the raw coal, thereby increasing the temperature of the water carried by the raw coal. Part of the water will evaporate due to the increase in temperature, thereby reducing the physical water content of the raw coal.

[0027] In a preferred embodiment, the steam branch anti-collision device 1.6 has two connected inclined surfaces, which are respectively located above the two sides of the steam branch 1.3, and the inclined direction is from the upper middle part of the steam branch 1.3 to the upper parts of the two sides diagonally downward. This structure can also prevent the raw coal from accumulating above it and facilitate the falling of the raw coal; optionally, the steam branch anti-collision device 1.6 uses angle steel as the raw material.

[0028] The steam branch pipe anti-collision device 1.6 can be fixedly connected to the inner wall of the raw coal bunker, and a plurality of suspension points can be further fixedly arranged at intervals at the lower end of the steam branch pipe anti-collision device 1.6 for suspending and supporting the steam branch pipe 1.3.

[0029] In order to discharge the water vapor evaporated by the raw coal due to the increase in temperature, a raw coal bunker top dust collector 6 is fixedly installed on the top of the raw coal bunker, which is equipped with a dust removal fan. The suction force can be used to discharge the steam escaping from the bunker out of the raw coal bunker to prevent the steam from condensing into water in the bunker, thereby improving the preheating and dehydration effect of the raw coal.

[0030] All valves can be operated manually, electrically or by other means according to the actual needs of the site. Figure 1The square warehouse shown can also be a round warehouse or other forms. At the same time, its structural form can be a steel structure or a concrete structure. Figure 1 It is not necessary for the connecting section of the heat exchange structure to pass through the raw coal bunker, and it is better to keep it inside the bunker, especially in a concrete structure.

[0031] The above are only preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined by the claims.

[0032] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

Claims

1. A method for online preheating of raw coal for blast furnace coal injection, characterized in that: It includes the following specific contents: renovate or build a new raw coal bunker, arrange multi-layer steam pipes in the height direction of the bunker body, connect both ends of the multi-layer steam pipes to the same main steam pipeline, and each layer of steam pipes passes through the wall of the raw coal bunker respectively, and connect to the heat exchange structure in the bunker. Install anti-collision devices above each layer of steam pipes and heat exchange structures in the bunker for protection. Drain pipes are connected under the outlet ends of each layer of steam pipes to discharge condensed water; a dust collector is connected to the top of the raw coal bunker to discharge water vapor generated after the raw coal is heated.

2. A blast furnace coal injection raw coal online preheating system, used to implement the method according to claim 1, characterized in that: The invention comprises a raw coal bunker, the outer side of which is provided with a steam main pipe (1) and an outlet main pipe (4), and a plurality of steam branch pipes (1.3) are connected between the two. Each steam branch pipe (1.3) penetrates into the raw coal bunker at different heights, and passes out of the raw coal bunker after arranging a heat exchange structure on a horizontal plane at the height. Each steam branch pipe (1.3) is also connected to a steam branch pipe drainage pipe (1.5) at the point where it passes out of the raw coal bunker. The outlet main pipe (4) and each steam branch pipe drainage pipe (1.5) are respectively connected to a steam trap (3.1); a steam branch pipe anti-collision device (1.6) is fixedly provided above each steam branch pipe (1.3) inside the raw coal bunker, and is used to prevent the impact and friction on the steam branch pipe (1.3) during the falling process of the raw coal.

3. The online preheating system for raw coal for blast furnace coal injection according to claim 2, characterized in that: The two ends of the steam branch pipe (1.3) are respectively provided with a steam branch pipe inlet valve (1.1) and a steam branch pipe outlet valve (1.2), and the steam main pipe (1) is provided with a steam main pipe valve (2) at the front end of all the steam branch pipes (1.3).

4. The online preheating system for raw coal for blast furnace coal injection according to claim 2 is characterized in that: The outlet main pipe (4) and each steam branch pipe drainage pipe (1.5) are also respectively connected to a plurality of valve components, including a first steam trap (1.4.1), wherein the first steam trap (1.4.1) on the steam branch pipe drainage pipe (1.5) is located close to one end of each steam branch pipe drainage pipe (1.5) connected to each steam branch pipe (1.3), and the first steam trap (1.4.1) on the outlet main pipe (4) is located at the rear end of all steam branch pipes (1.3); the valve components also include a second steam trap (1.4.2) located at the inlet end of each steam trap (3.1) and a fourth steam trap (1.4.4) located at the outlet end of the steam trap (3.1), and a bypass pipeline is connected between the inlet end of the second steam trap (1.4.2) and the outlet end of the fourth steam trap (1.4.4), on which a third steam trap (1.4.3) is arranged.

5. The online preheating system for raw coal for blast furnace coal injection according to claim 2, characterized in that: The heat exchange structure is a U-shaped coil, which includes a plurality of parallel straight pipe sections and connecting sections at the ends of the straight pipe sections, wherein the spacing between adjacent straight pipe sections is equal, and the connecting sections are alternately distributed at both ends of the straight pipe sections.

6. The online preheating system for raw coal for blast furnace coal injection according to claim 2, characterized in that: The steam branch pipe anti-collision device (1.6) has two connected inclined surfaces, which are respectively located above the two sides of the steam branch pipe (1.3), and the inclined direction is from the upper middle part of the steam branch pipe (1.3) to the upper parts of the two sides and obliquely downward.

7. The online preheating system for raw coal for blast furnace coal injection according to claim 2, characterized in that: The steam branch pipe anti-collision device (1.6) is fixedly connected to the inner wall of the raw coal bunker, and a plurality of hanging points are fixedly arranged at intervals at the lower end of the steam branch pipe anti-collision device (1.6) for hanging and supporting the steam branch pipe (1.3).

8. The online preheating system for raw coal for blast furnace coal injection according to claim 2, characterized in that: A raw coal bunker top dust collector (6) is fixedly arranged on the top of the raw coal bunker, and a dust removal fan is arranged inside the raw coal bunker to discharge water vapor generated after the raw coal is heated.

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