Dry gas preparation device and process applied to blast furnace coal injection and pulverizing system

Abstract

The invention belongs to the technical field of blast furnace ironmaking processes, and discloses a dry gas preparation device and process applied to a blast furnace coal injection and pulverizing system. The inert dry gas preparation device applied to the blast furnace coal injection pulverizing system can comprise a combustion furnace, a coal mill, a CO2 supply header pipe, a coal gas pipeline, a combustion air pipeline and a dry gas pipeline, the combustion furnace comprises a coal gas inlet, a smoke outlet and a CO2 supply port, the coal gas pipeline and the combustion air pipeline are connected with the coal gas inlet at the same time, and the CO2 supply port is connected with the coal mill. The CO2 supply header pipe is connected with the CO2 supply port, and the dry gas pipeline is connected between the flue gas outlet and the gas inlet of the coal mill. According to the dry gas preparation device and process applied to the blast furnace coal injection pulverizing system, the problems that in the prior art, the water content of pulverized coal is high, the system operation potential safety hazard is large, and the economical efficiency is poor are solved.

Description

Technical Field

[0001] The invention relates to the technical field of blast furnace ironmaking technology, and in particular to a drying gas preparation device and process applied to a blast furnace coal injection pulverizing system. Background Art

[0002] The blast furnace coal injection process is a key technology in ironmaking production. The blast furnace coal injection process mainly consists of a pulverizing system and an injection system. Among them, the pulverizing system needs to prepare coal powder under an inert dry atmosphere. There are two main ways to obtain inert dry gas in the prior art: first, a mixture of combustion furnace flue gas and hot blast furnace flue gas; second, a mixture of combustion furnace flue gas and self-circulating flue gas.

[0003] However, the above two methods used in the prior art to obtain inert dry gas have the following defects: 1) The construction cost of the hot blast furnace flue gas induction system is high, and the economy is poor when the pulverizing system is far away from the hot blast furnace; 2) The moisture content of the self-circulating flue gas is too high (>8%), resulting in excessive moisture content in the prepared coal powder (>2%), which easily causes blockage of the injection pipeline; 3) The control accuracy of the oxygen concentration in the mixed gas is insufficient, and there is a risk of coal powder explosion. Summary of the invention

[0004] In order to solve the problems of high moisture content of pulverized coal, great hidden dangers in system operation and poor economy in the prior art, the present invention proposes a drying gas preparation device and process for a blast furnace coal injection pulverizing system.

[0005] The inert dry gas preparation device applied to the blast furnace coal injection pulverizing system according to the present invention comprises: a combustion furnace, a coal mill, a CO2 gas supply main pipe, a gas pipeline, a combustion air pipeline and a dry gas pipeline, wherein the combustion furnace comprises a gas inlet, a flue gas outlet and a CO2 gas supply port, the gas pipeline and the combustion air pipeline are connected to the gas inlet at the same time, the CO2 gas supply main pipe is connected to the CO2 gas supply port, and the dry gas pipeline is connected between the flue gas outlet and the air inlet of the coal mill.

[0006] Furthermore, the dry gas preparation device applied to the blast furnace coal injection pulverizing system also includes an O2 detection system, a first branch pipe and a second branch pipe, wherein the CO2 gas supply main pipe is connected to the CO2 gas supply port through the first branch pipe, the O2 detection system is arranged on the dry gas pipeline, and the second branch pipe is connected between the dry gas pipeline between the O2 detection system and the coal mill and the CO2 gas supply main pipe.

[0007] Furthermore, the dry gas preparation device applied to the blast furnace coal injection pulverizing system also includes a venting pipeline connected to the flue gas outlet, and the dry gas pipeline is connected between the venting pipeline and the air inlet of the coal mill.

[0008] Furthermore, a combustion-supporting blower is connected to the combustion-supporting air pipeline.

[0009] According to the dry gas preparation process applied to the blast furnace coal injection pulverizing system of the present invention, the dry gas preparation device applied to the blast furnace coal injection pulverizing system is adopted, including: introducing CO2 gas into the combustion furnace, making the mixed gas of CO2 gas and the combustion furnace flue gas as inert dry gas, and introducing it into the coal mill through the dry gas pipeline.

[0010] Furthermore, the dry gas preparation process applied to the blast furnace coal injection pulverizing system also includes: using an O2 detection system to monitor the O2 concentration in the inert dry gas in the dry gas pipeline in real time, and when the O2 concentration of the inert dry gas exceeds a safety threshold, introducing CO2 into the dry gas pipeline to reduce the O2 concentration in the inert dry gas.

[0011] Furthermore, combustion-supporting air and coal gas are introduced into the combustion furnace for combustion to generate combustion furnace flue gas.

[0012] Furthermore, the coal gas includes at least one of blast furnace gas, converter gas and coke oven gas.

[0013] Furthermore, the dry gas preparation process applied to the blast furnace coal injection pulverizing system also includes: dispersing the gas in the combustion furnace when the combustion furnace is installed and the furnace is baked.

[0014] Furthermore, the CO2 gas is introduced from a top gas circulating oxygen blast furnace or an ironmaking blast furnace top gas CO2 recovery system.

[0015] Compared with the drying gas process of the existing pulverizing system, the drying gas preparation device and process for the blast furnace coal injection pulverizing system of the present invention uses CO2 gas instead of hot blast furnace flue gas or self-circulating flue gas, and uses the mixed gas of combustion furnace flue gas and CO2 gas as inert drying gas, which solves the problem that the pulverizing production of mixed coal and bituminous coal must be carried out in an inert drying gas environment. It breaks through the dependence of traditional processes on hot blast furnace flue gas, realizes the resource utilization of CO2 in the ironmaking process, and provides a new drying gas process for pulverizing system under the condition that hot blast furnace flue gas is uneconomical or there is no hot blast furnace flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a dry gas preparation device applied to a blast furnace coal injection pulverizing system according to an embodiment of the present invention, which shows the process of a dry gas preparation process applied to a blast furnace coal injection pulverizing system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings.

[0018] Figure 1FIG. 1 shows the structure of an inert dry gas preparation device 100 applied to a blast furnace coal injection pulverizing system according to an embodiment of the present invention. Figure 1 As shown, the inert dry gas preparation device 100 applied to the blast furnace coal injection pulverizing system may include: a combustion furnace 1, a coal mill 9, a CO2 gas supply main pipe 5, a gas pipeline 2, a combustion air pipeline 3 and a dry gas pipeline 7. Among them, the combustion furnace 1 may include a gas inlet 11, a flue gas outlet 13 and a CO2 gas supply port 12, the gas pipeline 2 and the combustion air pipeline 3 are connected to the gas inlet 11 at the same time, the CO2 gas supply main pipe 5 is connected to the CO2 gas supply port 12, and the dry gas pipeline 7 is connected between the flue gas outlet 13 and the air inlet of the coal mill 9.

[0019] In the inert dry gas preparation device 100 applied to the blast furnace coal injection pulverizing system of the embodiment of the present invention, the coal gas from the gas pipeline 2 and the combustion-supporting air from the self-ignition air pipeline 3 enter the combustion furnace 1 through the gas inlet 11 to burn and form combustion furnace flue gas, and the combustion furnace flue gas is directly mixed with the CO2 gas from the CO2 gas supply main 5 to form a stable inert atmosphere with an oxygen content of ≤5%. Compared with the existing hot blast furnace flue gas solution (oxygen content 8-12%), the explosion-proof safety is improved by 60%. Therefore, the inert dry gas preparation device 100 applied to the blast furnace coal injection pulverizing system of the embodiment of the present invention greatly optimizes the inert environment. Compared with the existing self-circulating flue gas solution, the inert dry gas preparation device 100 applied to the blast furnace coal-injection pulverizing system of the embodiment of the present invention uses CO2 gas to replace the self-circulating flue gas, and the moisture content of the dry gas can be reduced from 8% to below 0.5%, the moisture content of the coal powder can be reduced from 2.5% to 1.2%, and the injection blockage rate is reduced by 90%. Therefore, the inert dry gas preparation device 100 applied to the blast furnace coal-injection pulverizing system of the embodiment of the present invention breaks through the limitation of excessively high moisture content in the prior art. In addition, the inert dry gas preparation device 100 applied to the blast furnace coal-injection pulverizing system of the embodiment of the present invention eliminates the long-distance hot blast furnace flue gas transportation pipeline, and realizes short-process inert atmosphere control through direct CO2 injection, which has both economic efficiency and process reliability, and the equipment investment cost can be reduced by 35-45%.

[0020] In such Figure 1In the preferred embodiment shown, the dry gas preparation device 100 applied to the blast furnace coal injection pulverizing system may also include an O2 detection system, a first branch pipe 51 and a second branch pipe 52. Among them, the CO2 gas supply main pipe 5 is connected to the CO2 gas supply port 12 through the first branch pipe 51, the O2 detection system 8 is arranged on the dry gas pipeline 7, and the second branch pipe 52 is connected between the dry gas pipeline 7 and the CO2 gas supply main pipe 5 located between the O2 detection system 8 and the coal mill 9. In this embodiment, the O2 detection system 8 is used to monitor the O2 concentration in the inert dry gas in the dry gas pipeline 7 in real time. When the O2 concentration of the inert dry gas exceeds the safety threshold, the second branch pipe 52 introduces CO2 gas into the dry gas pipeline 7 to reduce the O2 concentration in the inert dry gas. Therefore, this embodiment dynamically supplements CO2 gas based on the O2 detection result, and can effectively control the oxygen content in the dry gas pipeline 7 even under fluctuating working conditions. This embodiment realizes accurate inertization of the whole process through the dual control mechanism of "combustion end premixing + pipeline dynamic compensation".

[0021] In such Figure 1 In the preferred embodiment shown, the dry gas preparation device 100 applied to the blast furnace coal injection pulverizing system may also include a venting pipeline 6 connected to the flue gas outlet 13, and a dry gas pipeline 7 is connected between the venting pipeline 6 and the air inlet of the coal mill 9. By providing the venting pipeline 6 connected to the flue gas outlet 13, the dangerous gas can be quickly discharged during the system start-up and shutdown stages, so that the explosion risk index is reduced from 0.25 to 0.05, and the safety redundancy is improved; the exhaust gas emission efficiency during the furnace baking stage can be increased by 70%, the system startup time is shortened by 40%, and the operational flexibility is enhanced; in addition, the negative pressure of the furnace can be maintained at -50±5Pa by adjusting the valve on the venting pipeline 6 to avoid the danger of positive pressure.

[0022] In such Figure 1 In the preferred embodiment shown, a combustion-supporting fan 4 can be connected to the combustion-supporting air pipeline 3. In this embodiment, the combustion-supporting fan 4 can be adjusted to achieve optimized combustion under all working conditions. The combustion-supporting fan 4 can accurately control the air volume (error ≤ 3%), so the gas combustion efficiency can reach 99.5%, which is 7.5% higher than the natural induced draft method (92%), so the combustion efficiency can be effectively improved; the flue gas 13 of the combustion furnace 1 has a flue gas temperature fluctuation of ≤ ± 5 ° C, which can ensure the temperature stability of the uniformity of coal powder drying; in addition, the combustion-supporting fan 4 can preferably be frequency-controlled, which can achieve stable operation within the load range of 30-110%, thereby increasing the load regulation capability.

[0023] According to the dry gas preparation process for a blast furnace coal injection pulverizing system according to an embodiment of the present invention, the dry gas preparation device 100 for a blast furnace coal injection pulverizing system is used. Figure 1As shown, it may include: introducing CO2 gas into the combustion furnace 1, making the mixed gas of CO2 gas and the combustion furnace flue gas serve as inert dry gas, and introducing it into the coal mill 9 through the dry gas pipeline 7.

[0024] Compared with the drying gas process of the existing pulverizing system, the drying gas preparation process applied to the blast furnace coal injection pulverizing system in the embodiment of the present invention uses CO2 gas instead of hot blast furnace flue gas or self-circulating flue gas, and uses the mixture of combustion furnace flue gas and CO2 gas as inert drying gas, which solves the problem that the pulverizing production of mixed coal and bituminous coal must be carried out in an inert drying gas environment. It breaks through the dependence of traditional processes on hot blast furnace flue gas, realizes the resource utilization of CO2 in the ironmaking process, and provides a new drying gas process applied to the pulverizing system under the conditions where the introduction of hot blast furnace flue gas is uneconomical or there is no hot blast furnace flue gas.

[0025] Furthermore, in Figure 1 In the preferred embodiment shown, the dry gas preparation process applied to the blast furnace coal injection pulverizing system may also include: using the O2 detection system 8 to monitor the O2 concentration in the inert dry gas in the dry gas pipeline 7 in real time, and when the O2 concentration of the inert dry gas exceeds the safety threshold, introducing CO2 gas into the dry gas pipeline 7 to reduce the O2 concentration in the inert dry gas. This embodiment dynamically supplements CO2 gas based on the O2 detection result, and can effectively control the oxygen content in the dry gas pipeline 7 even under fluctuating working conditions. This embodiment realizes accurate inertization of the entire process through the dual control mechanism of "combustion end premixing + pipeline dynamic compensation".

[0026] Preferably, the oxygen concentration fluctuation range can be controlled within ±0.3% through online O2 monitoring (accuracy ±0.1%) and PID automatic adjustment, which is 6 times more accurate than the traditional manual adjustment method (fluctuation ±2%). When necessary, CO2 gas is injected in stages through the second branch pipe 52, which can make the CO2 utilization rate reach 98%, and the O2 concentration can be reduced to below the safety threshold within 2 seconds under abnormal conditions.

[0027] In such Figure 1 In the preferred embodiment shown, the combustion air provided by the combustion air pipeline 3 and the coal gas provided by the coal gas pipeline 2 are introduced into the combustion furnace 1 for combustion to generate combustion furnace flue gas. Preferably, the coal gas may include at least one of blast furnace gas, converter gas and coke oven gas. CO2 gas may be introduced from a top gas circulating oxygen blast furnace or an ironmaking blast furnace top gas CO2 recovery system.

[0028] The dry gas preparation process applied to the blast furnace coal injection pulverizing system in the embodiment of the present invention supports multiple sources of coal gas fuel and CO2 gas, breaking through the traditional single gas source limitation and realizing the coordinated optimization of energy throughout the entire process of a steel enterprise.

[0029] In addition, the dry gas preparation process applied to the blast furnace coal injection pulverizing system of the embodiment of the present invention may also include: dispersing the gas in the combustion furnace when the combustion furnace is installed and the furnace is dried. It is used for starting the combustion furnace and the dry gas system. When the dry gas system is working normally, the venting pipeline can be in a closed state and does not participate in the operation. When the new combustion furnace is installed and the furnace is dried, the venting pipeline 6 can be opened for venting, or when the dry gas system is started, the venting pipeline 6 is changed from open to closed.

[0030] The process steps of the drying gas preparation process applied to the blast furnace coal injection pulverizing system according to the embodiment of the present invention can be specifically as follows:

[0031] 1) The combustion air provided by the combustion fan 4 is burned in the combustion furnace 1 through the combustion air pipeline 3 and the coal gas provided by the gas pipeline 2 to generate high-temperature combustion furnace flue gas. This process requires a reasonable ratio of the amount of combustion air and coal gas to achieve the purpose of full combustion and ensure that the generated combustion furnace flue gas is an inert gas;

[0032] 2) CO2 gas enters the combustion furnace 1 through the CO2 gas supply main pipe 5 and the first branch pipe 51 connected to the combustion furnace 1 and mixes with the combustion furnace flue gas to generate inert dry gas;

[0033] 3) The generated inert dry gas enters the coal mill 9 through the dry gas pipeline 7 connected to the coal mill 9, and dries and transports the coal powder in the coal mill 9;

[0034] 4) The oxygen content in the dry gas is monitored in real time by the O2 detection system 8 connected to the dry gas pipeline 7. When the oxygen content exceeds the warning value, CO2 gas is mixed into the dry gas through the second branch pipe 52 to reduce the O2 concentration in the dry gas and ensure the safety of the system.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A drying gas preparation device for a blast furnace coal injection pulverizing system, characterized in that: include: A combustion furnace, a coal mill, a CO2 gas supply main, a gas pipeline, a combustion-supporting air pipeline and a dry gas pipeline, wherein the combustion furnace includes a gas inlet, a flue gas outlet and a CO2 gas supply port, the gas pipeline and the combustion-supporting air pipeline are connected to the gas inlet at the same time, the CO2 gas supply main is connected to the CO2 gas supply port, and the dry gas pipeline is connected between the flue gas outlet and the air inlet of the coal mill.

2. The drying gas preparation device for a blast furnace coal injection pulverizing system according to claim 1, characterized in that: The dry gas preparation device applied to the blast furnace coal injection pulverizing system also includes an O2 detection system, a first branch pipe and a second branch pipe, wherein the CO2 gas supply main pipe is connected to the CO2 gas supply port through the first branch pipe, the O2 detection system is arranged on the dry gas pipeline, and the second branch pipe is connected between the dry gas pipeline between the O2 detection system and the coal mill and the CO2 gas supply main pipe.

3. The drying gas preparation device for a blast furnace coal injection pulverizing system according to claim 1 or 2, characterized in that: The dry gas preparation device applied to the blast furnace coal injection pulverizing system also includes a venting pipeline connected to the flue gas outlet, and the dry gas pipeline is connected between the venting pipeline and the air inlet of the coal mill.

4. The drying gas preparation device for a blast furnace coal injection pulverizing system according to claim 1 or 2, characterized in that: The combustion-supporting air pipeline is connected with a combustion-supporting blower.

5. A drying gas preparation process for a blast furnace coal injection pulverizing system, using a drying gas preparation device for a blast furnace coal injection pulverizing system according to any one of claims 1 to 4, characterized in that: include: CO2 gas is introduced into the combustion furnace, and a mixed gas of the CO2 gas and the flue gas of the combustion furnace is used as an inert dry gas, and is introduced into the coal mill through the dry gas pipeline.

6. The drying gas preparation process for a blast furnace coal injection pulverizing system according to claim 5, characterized in that: The dry gas preparation process applied to the blast furnace coal injection pulverizing system also includes: using the O2 detection system to monitor the O2 concentration in the inert dry gas in the dry gas pipeline in real time, and when the O2 concentration of the inert dry gas exceeds a safety threshold, introducing CO2 into the dry gas pipeline to reduce the O2 concentration in the inert dry gas.

7. The drying gas preparation process for a blast furnace coal injection pulverizing system according to claim 5 or 6, characterized in that: Combustion-supporting air and coal gas are introduced into the combustion furnace for combustion to generate the combustion furnace flue gas.

8. The drying gas preparation process for a blast furnace coal injection pulverizing system according to claim 7, characterized in that: The coal gas includes at least one of blast furnace gas, converter gas and coke oven gas.

9. The drying gas preparation process for a blast furnace coal injection pulverizing system according to claim 5 or 6, characterized in that: The dry gas preparation process applied to the blast furnace coal injection pulverizing system also includes: dispersing the gas in the combustion furnace after the combustion furnace is installed and then baked.

10. The drying gas preparation process for a blast furnace coal injection pulverizing system according to claim 5 or 6, characterized in that: The CO2 gas is introduced from a top gas circulating oxygen blast furnace or an ironmaking blast furnace top gas CO2 recovery system.

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