Preheating system for blast furnace ironmaking pulverized coal injection
Through the design of coal transportation pipelines with internal and external double-layer structures and the waste flue gas heating method, the low and uneven heat transfer efficiency of the blast furnace coal spraying preheating system is solved, efficient and uniform coal powder preheating is achieved, and the coal powder combustion rate and blast furnace smelting efficiency are improved.
Patent Information
- Application Number
- CN202422505985.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-16
- Publication Date
- 2025-07-04
- Estimated Expiration
- 2034-10-16
AI Technical Summary
The existing blast furnace coal spraying preheating system has problems such as low heat transfer efficiency, large heat dissipation, uneven preheating and low coal powder combustion rate. Especially after the coal spraying ratio increases, the coal powder cannot be completely burned, resulting in a decrease in blast furnace smelting efficiency.
The coal transportation pipeline design adopts a double-layer structure of the inner and outer structure. The waste flue gas from the blast furnace flows in the core pipe and the horizontal pipe, and flows in opposite to the coal powder for heat transfer. Combined with the design of the spiral pipe and the ring pipe, uniform heating from the inside to the outside is achieved, and the coal powder is prevented from sinking through the flow-blocking ring plate and steel brush, which improves heat utilization and heating efficiency.
The high heat utilization rate and uniform heating are achieved, and the coal powder temperature is increased to 250-350℃, which significantly increases the combustion rate of coal powder, reduces the preheating cost and energy consumption, and ensures the antetraquency of blast furnace smelting.
Smart Images
Figure CN223061001U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of preheating pulverized coal for blast furnace injection, and specifically relates to a preheating system for injecting pulverized coal in blast furnace ironmaking. Background Art
[0002] During the smelting process of a blast furnace, it is necessary to directly inject finely ground anthracite pulverized coal, bituminous pulverized coal, or a mixture of both into the furnace from the blast furnace tuyere. During the blast furnace smelting process, it plays the role of providing heat and acting as a reducing agent to replace coke, thereby reducing the coke ratio and the cost of pig iron. Blast furnace coal injection is a major technological revolution in modern blast furnace smelting. More than 90% of pig iron is smelted by blast furnaces injecting fuel. However, with the increase in the injection volume, when the coal injection ratio increases to a certain limit, the reduction amplitude of the coke ratio will be greatly reduced. The main reason is that the injected pulverized coal cannot be completely burned in front of the tuyere. The unburned pulverized coal will be carried out of the raceway by the rising gas and adhered to the slag when reaching the slag formation zone, increasing the viscosity of the initial slag, deteriorating the permeability of the burden column, making it unfavorable for the smooth operation of the blast furnace, and even some carbon particles are carried out of the furnace and wasted. How to improve the combustion rate of pulverized coal in front of the tuyere has become the key to further increasing the coal injection ratio. Experiments have proved that after the pulverized coal is preheated, the burnout rate of the pulverized coal can be improved and the fuel ratio can be reduced.
[0003] At present, the pipeline pneumatic conveying method is generally adopted in blast furnace coal injection. The preheating of pulverized coal is generally to wind heating wires on the outer wall of the coal conveying pipeline, or to sleeved a jacket on the outer wall of the coal conveying pipeline and introduce high-temperature gas into the jacket. There are the following problems: First, during preheating, it is necessary to first heat the coal conveying pipeline, and the heat is transferred to the pulverized coal inside through the coal conveying pipeline. This way of heat transfer has low efficiency and a large heat dissipation waste rate, and the preheating cost of pulverized coal is high; Second, the heat is transferred from the outside to the inside, and the pulverized coal located in the center of the coal conveying pipeline cannot be fully preheated, resulting in uneven preheating; Third, generally speaking, the higher the temperature of the pulverized coal, the more conducive to the complete combustion of the pulverized coal. At present, the pulverized coal can only be heated to about 160°C after preheating, and the preheating effect and the utilization rate of the pulverized coal still need to be improved. Therefore, it is objectively necessary to develop a preheating system for injecting pulverized coal in blast furnace ironmaking with less heat waste, uniform heating, and good preheating effect. Summary of the Utility Model
[0004] The purpose of the utility model is to provide a preheating system for injecting pulverized coal in blast furnace ironmaking with less heat dissipation, uniform heating, and good preheating effect.
[0005] The object of the present utility model is achieved as follows. It includes a connected coal conveying straight pipe and a coal conveying elbow pipe. An inner extension strip is arranged in the coal conveying straight pipe near the feeding end. One end of the inner extension strip extends to the outside of the coal conveying straight pipe. An air outlet channel is processed in the inner extension strip. A core pipe is concentrically arranged in the coal conveying straight pipe. One end of the core pipe is communicated with the air outlet channel, and the end of the core pipe is hermetically and rotationally connected with the inner extension strip. An air inlet chamber is arranged on the outer wall of the coal conveying elbow pipe. The other end of the core pipe extends out of the air inlet chamber and is drivingly connected with a driving device. Vent holes are processed on the core pipe in the air inlet chamber. A plurality of cross pipes with both ends blocked are circumferentially and evenly distributed in the annular space between the core pipe and the side wall of the coal conveying straight pipe. Both ends of the cross pipe are respectively communicated with the core pipe through connecting pipes. A flue gas inlet is arranged on the air inlet chamber.
[0006] Further, a spiral pipe is arranged in the air inlet chamber. The air inlet end of the spiral pipe is communicated with a nitrogen pipe arranged on the air inlet chamber, and the air outlet end of the spiral pipe is communicated with the coal conveying elbow pipe.
[0007] Further, a ring pipe is concentrically arranged inside the air outlet end of the coal conveying straight pipe. A plurality of spray holes are respectively circumferentially and evenly distributed on the outer side and the inner side of the ring pipe. The air outlet end of the spiral pipe extends into the coal conveying straight pipe and is communicated with the ring pipe.
[0008] Further, a plurality of flow blocking ring plates are arranged on the core pipe at intervals along its length direction.
[0009] Further, a reflective layer and a heat insulating layer are sequentially arranged on the outer walls of both the coal conveying straight pipe and the coal conveying elbow pipe.
[0010] Further, steel brushes are arranged on the outer walls of the cross pipes, and the bristles of the steel brushes are in contact with the inner wall of the coal conveying straight pipe.
[0011] In the present utility model, the coal conveying straight pipe and the coal conveying elbow are pneumatic conveying pipelines for pulverized coal. The pulverized coal enters from the feeding end of the coal conveying straight pipe, and then is discharged after passing through the coal conveying straight pipe and the coal conveying elbow in sequence. When the system operates, the driving device drives the core pipe to rotate, and the core pipe drives the cross pipe to rotate. At the same time, the waste flue gas of the blast furnace hot stove is introduced into the air inlet chamber through the flue gas inlet, sent into the core pipe through the ventilation holes, and then flows along the core pipe, and is shunted into each cross pipe through the connecting pipe. At this time, part of the flue gas flows in the core pipe, and part of the flue gas flows in each cross pipe, and finally converges into the core pipe again and is discharged through the air outlet channel inside the inner extension bar. In the above process, the pulverized coal flows in the coal conveying straight pipe, and the waste flue gas of the blast furnace hot stove flows in the core pipe and the cross pipe. Moreover, the conveying direction of the pulverized coal is opposite to the flowing direction of the flue gas, and the two flow towards each other. The heat in the flue gas is transferred from the outer walls of the core pipe and the cross pipe to the pulverized coal. All the heat dissipated by the flue gas will be transferred to the inside of the coal conveying straight pipe for heating the pulverized coal. There is no problem of direct heat dissipation to the outside, with high heat utilization rate, small heat dissipation and waste rate, and the heat source comes from the waste flue gas of the blast furnace hot stove, without additional energy consumption, which can reduce the preheating cost of the pulverized coal. Secondly, when the system operates, the flue gas flows in the core pipe and the cross pipe. The heat of the flue gas in the core pipe is transferred to the central position of the coal conveying straight pipe to heat the pulverized coal from the inside to the outside, which can fully heat the pulverized coal located in the center of the coal conveying straight pipe. The cross pipes are evenly distributed in a circle. When the cross pipes rotate, an annular heating area is formed at the position of the pitch circle, which interacts with the heat dissipated by the core pipe and can heat the pulverized coal more evenly, with better heating efficiency for the pulverized coal. In addition, the system heats the pulverized coal from the inside to the outside, with high heat utilization rate, and can heat the pulverized coal to about 250 - 350 °C or even higher. Compared with the situation where the pulverized coal can only be heated to about 160 °C, it is more conducive to the full combustion of the pulverized coal. To sum up, the present utility model has the advantages of less heat dissipation, uniform heating, and good preheating effect. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 is a schematic diagram of the overall structure of the present utility model;
[0013] In the figure: 1 - coal conveying straight pipe, 2 - coal conveying elbow, 3 - inner extension bar, 4 - core pipe, 5 - air inlet chamber, 6 - driving device, 7 - ventilation hole, 8 - cross pipe, 9 - flue gas inlet, 10 - spiral pipe, 11 - nitrogen pipe, 12 - ring pipe, 13 - jet hole, 14 - baffle ring plate, 15 - reflection layer, 16 - heat insulation layer, 17 - steel brush. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0014] The present utility model will be further described below with reference to the accompanying drawings, but it is not limited to the present utility model in any way. Any change or improvement based on the present utility model belongs to the protection scope of the present utility model.
[0015] As Figure 1 shown, the utility model includes a connected coal conveying straight pipe 1 and a coal conveying elbow pipe 2. The structures of the coal conveying straight pipe 1 and the coal conveying elbow pipe 2 are existing pulverized coal pneumatic conveying pipelines. The angle of the coal conveying elbow pipe 2 can be determined according to the actual situation, which is convenient for on-site pipe laying and the installation of the air inlet chamber 5. An inner extension bar 3 is arranged in the coal conveying straight pipe 1 near the feeding end. One end of the inner extension bar 3 extends to the outside of the coal conveying straight pipe 1. An air outlet channel is processed in the inner extension bar 3. A core pipe 4 is concentrically arranged in the coal conveying straight pipe 1. One end of the core pipe 4 is communicated with the air outlet channel, and the end of the core pipe 4 is hermetically and rotatably connected with the inner extension bar 3. An air inlet chamber 5 is arranged on the outer wall of the coal conveying elbow pipe 2. The other end of the core pipe 4 extends out of the air inlet chamber 5 and is drivingly connected with a driving device 6. The driving device 6 is of an existing structure, including components such as a motor and a reducer. Parameters such as power and speed are determined according to the actual situation and only need to meet the use requirements. Ventilation holes 7 are processed on the core pipe 4 in the air inlet chamber 5. A plurality of cross pipes 8 with both ends blocked are circumferentially and evenly distributed in the annular space between the core pipe 4 and the side wall of the coal conveying straight pipe 1. Both ends of the cross pipe 8 are respectively communicated with the core pipe 4 through connecting pipes. A flue gas inlet 9 is arranged on the air inlet chamber 5.
[0016] In the present utility model, the straight coal conveying pipe 1 and the bent coal conveying pipe 2 are pneumatic conveying pipelines for pulverized coal. Pulverized coal enters the straight coal conveying pipe 1 from the feed end, and then is discharged into the pulverized coal conveying pipelines such as the distributor after passing through the straight coal conveying pipe 1 and the bent coal conveying pipe 2 in sequence. When the system operates, the driving device 6 drives the core pipe 4 to rotate, and the core pipe 4 drives the cross pipe 8 to rotate. At the same time, the waste flue gas from the blast furnace hot stove is introduced into the intake chamber 5 through the flue gas inlet 9, sent into the core pipe 4 through the ventilation holes 7, and then flows along the core pipe 4, and is shunted to each cross pipe 8 through the connecting pipe. At this time, part of the flue gas flows in the core pipe 4, and part of the flue gas flows in each cross pipe 8, and finally converges into the core pipe 4 again and is discharged through the air outlet channel inside the inner extension bar 3. In the above process, the pulverized coal flows in the straight coal conveying pipe 1, and the waste flue gas from the blast furnace hot stove flows in the core pipe 4 and the cross pipe 8. The conveying direction of the pulverized coal is opposite to the flowing direction of the flue gas, and the two flow towards each other. The heat in the flue gas is transferred from the outer walls of the core pipe 4 and the cross pipe 8 to the pulverized coal. All the heat dissipated by the flue gas will be transferred to the inside of the straight coal conveying pipe 1 for heating the pulverized coal, and there is no problem of direct heat dissipation to the outside. It has a high heat utilization rate, a small heat dissipation and waste rate, and the heat source comes from the waste flue gas of the blast furnace hot stove, without additional energy consumption, which can reduce the preheating cost of the pulverized coal; secondly, when the system operates, the flue gas flows in the core pipe 4 and the cross pipe 8. The heat of the flue gas in the core pipe 4 is transferred to the central position of the straight coal conveying pipe 1 to heat the pulverized coal from the inside to the outside, and the pulverized coal located in the center of the straight coal conveying pipe 1 can be fully heated. The cross pipes 8 are evenly distributed on the circumference. When the cross pipes 8 rotate, an annular heating area is formed at this pitch circle position, which interacts with the heat dissipated by the core pipe 4, and can heat the pulverized coal more evenly, and has a good heating efficiency for the pulverized coal; in addition, the system heats the pulverized coal from the inside to the outside, with a high heat utilization rate, and can heat the pulverized coal to about 250 - 350 °C or even higher. Compared with the situation where the pulverized coal can only be heated to about 160 °C, it has a better preheating effect and is more conducive to the full combustion of the pulverized coal.
[0017] A spiral pipe 10 is arranged in the intake chamber 5. The intake end of the spiral pipe 10 is communicated with a nitrogen pipe 11 arranged on the intake chamber 5, and the outlet end of the spiral pipe 10 is communicated with the bent coal conveying pipe 2. Nitrogen is introduced into the spiral pipe 10, absorbs the heat in the waste flue gas from the blast furnace hot stove in the spiral pipe 10 to obtain nitrogen with a higher temperature, and then the heated nitrogen is introduced into the bent coal conveying pipe 2 to heat the pulverized coal and further increase the temperature of the pulverized coal.
[0018] Inside the air outlet end of the coal conveying straight pipe 1, a ring pipe 12 is concentrically arranged. A plurality of air injection holes 13 are respectively circumferentially and evenly distributed on the outer side and the inner side of the ring pipe 12. After the air outlet end of the spiral pipe 10 extends into the coal conveying straight pipe 1, it is communicated with the ring pipe 12. The heated nitrogen is introduced into the ring pipe 12. Part of the nitrogen is ejected from the air injection holes 13 on the outer side of the ring pipe 12, and the other part of the nitrogen is ejected from the air injection holes 13 on the inner side of the ring pipe 12, so that the nitrogen can be sprayed into the pulverized coal more evenly, and then the pulverized coal is heated in a direct contact manner, further increasing the temperature of the pulverized coal and further promoting the complete combustion of the pulverized coal after it enters the blast furnace tuyere.
[0019] A plurality of baffle ring plates 14 are arranged at intervals along the length direction of the core pipe 4. The pulverized coal is conveyed in a fluidized state in the coal conveying straight pipe 1. When the pulverized coal hits the baffle ring plate 14, its flow direction will change, generating a certain amount of turbulence, which has two functions. One is to change the flow direction of the pulverized coal, making the flow trajectory of the pulverized coal in an S shape, increasing the heating time of the pulverized coal and improving the heating effect. The other is to generate turbulence to prevent the pulverized coal from sinking and ensure that the pulverized coal is carried away before sinking.
[0020] On the outer walls of the coal conveying straight pipe 1 and the coal conveying elbow 2, a reflective layer 15 and a heat insulation layer 16 are sequentially arranged. The reflective layer 15 is a prior art and can reflect the thermal radiation emitted from the wall of the coal conveying straight pipe 1 back to continue heating the pulverized coal. At the same time, the heat insulation layer 16 can block the loss of heat and reduce the waste of heat.
[0021] A steel brush 17 is arranged on the outer wall of the horizontal pipe 8, and the bristles of the steel brush 17 are in contact with the inner wall of the coal conveying straight pipe 1. Considering that due to the relatively high humidity or agglomeration of the pulverized coal, or the pulverized coal hitting components such as the core pipe 4 and the horizontal pipe 8, etc., a small amount of pulverized coal may sink. If it is not cleaned in time, with the extension of the use time, it will continuously accumulate at the bottom of the coal conveying straight pipe 1, which is not conducive to the long-term normal operation of the pulverized coal conveying. In order to prevent the pulverized coal from sinking and accumulating, a steel brush 17 is arranged on the outer wall of the horizontal pipe 8. When the core pipe 4 drives the horizontal pipe 8 to rotate, the steel brush 17 is also driven to rotate. During the rotation process, the steel brush 17 will scrape against the inner wall of the coal conveying straight pipe 1, throwing off the adhered and accumulated pulverized coal so that it is carried away by the subsequent pulverized coal, thereby solving the problem of pulverized coal adhesion and accumulation and ensuring the smoothness of the coal conveying straight pipe 1.
Claims
1. A preheating system for pulverized coal injection in blast furnace ironmaking, comprising a connected straight coal conveying pipe (1) and a bent coal conveying pipe (2), characterized in that : An inner extension bar (3) is arranged in the straight coal conveying pipe (1) near the feeding end. One end of the inner extension bar (3) extends outside the straight coal conveying pipe (1). An air outlet channel is processed in the inner extension bar (3). A core pipe (4) is concentrically arranged in the straight coal conveying pipe (1). One end of the core pipe (4) is communicated with the air outlet channel, and the end of the core pipe (4) is hermetically and rotationally connected with the inner extension bar (3). An air inlet chamber (5) is arranged on the outer wall of the coal conveying elbow (2). The other end of the core pipe (4) extends out of the air inlet chamber (5) and is drivingly connected with a driving device (6). Ventilation holes (7) are processed on the core pipe (4) in the air inlet chamber (5). A plurality of cross pipes (8) with both ends blocked are circumferentially and uniformly distributed in the annular space between the core pipe (4) and the side wall of the straight coal conveying pipe (1). Both ends of the cross pipe (8) are respectively communicated with the core pipe (4) through connecting pipes. A flue gas inlet (9) is arranged on the air inlet chamber (5).
2. The preheating system for pulverized coal injection in blast furnace ironmaking according to claim 1, characterized in that : A spiral pipe (10) is arranged in the air inlet chamber (5). The air inlet end of the spiral pipe (10) is communicated with a nitrogen pipe (11) arranged on the air inlet chamber (5). The air outlet end of the spiral pipe (10) is communicated with the coal conveying elbow (2).
3. The preheating system for injecting pulverized coal in blast furnace ironmaking according to claim 2, characterized in that : A ring pipe (12) is concentrically arranged inside the air outlet end of the straight coal conveying pipe (1). A plurality of spray holes (13) are respectively circumferentially and uniformly distributed on the outer side and the inner side of the ring pipe (12). The air outlet end of the spiral pipe (10) extends into the straight coal conveying pipe (1) and is communicated with the ring pipe (12).
4. The preheating system for pulverized coal injection in blast furnace ironmaking according to claim 1, characterized in that : A plurality of flow blocking ring plates (14) are arranged on the core pipe (4) at intervals along its length direction.
5. The preheating system for injecting pulverized coal in blast furnace ironmaking according to claim 1, characterized in that : Reflection layers (15) and heat insulation layers (16) are sequentially arranged on the outer walls of the straight coal conveying pipe (1) and the coal conveying elbow (2).
6. The preheating system for injecting pulverized coal in blast furnace ironmaking according to claim 1, characterized in that : Steel brushes (17) are arranged on the outer walls of the cross pipes (8). The bristles of the steel brushes (17) are in contact with the inner wall of the straight coal conveying pipe (1).