Improved system and method for coal injection into a converter gasification flue

Abstract

The application provides a material improvement system and method for coal injection of converter flue gas vaporization, and belongs to the field of metallurgical energy saving and environmental protection, wherein the material improvement system for coal injection of converter flue gas vaporization comprises a pulverized coal injection unit, a limestone powder injection unit and a cyclone dust removal unit connected with the pulverized coal injection unit and the limestone powder injection unit; the cyclone dust removal unit comprises a cyclone dust collector, and a fine particle injection port and a coarse particle recovery port are arranged on the cyclone dust collector. The application adds the cyclone dust removal unit to introduce the pulverized coal into the cyclone dust collector for treatment, and simultaneously adds the limestone powder injection unit to separate the large particles and the small particles in the mixture of the pulverized coal and the limestone powder by the cyclone dust collector, so that the large particles are used for blast furnace coal injection, and the small particles enter the converter coal injection system, the particle size of the pulverized coal and the limestone powder entering the converter coal injection system is optimized, the kinetic condition of the reaction is improved, the efficient conversion of the pulverized coal in the flue gas is realized, and the waste of the pulverized coal resources is reduced.

Description

Technical Field

[0001] This invention relates to the field of metallurgical energy conservation and environmental protection technology, specifically to a material improvement system and method for pulverized coal injection in converter gasification flue. Background Technology

[0002] Converter steelmaking accounts for approximately 90% of China's steel production. The process generates a large amount of dust-laden flue gas with a temperature of about 1400-1600℃. When the flue gas meets certain recovery conditions, it can be recovered as converter gas. Converter gas is an important byproduct of the steel industry and also a crucial secondary energy source. However, the flue gas contains about 20% CO2, which affects its calorific value and results in relatively high carbon emissions.

[0003] To address the problems of low gas recovery rate, poor recovery quality, and high carbon emissions, researchers have proposed injecting pulverized coal into the converter gasification flue to reduce carbon emissions. The principle is to utilize the sensible heat of the high-temperature flue gas from the converter, as well as the catalytic effect of the large amount of metal oxides present in the flue dust, to rapidly react carbon in the carbon-containing solid waste with CO2 to generate high-calorific-value CO. The recovered high-quality gas is then refined and separated to obtain high-quality converter gas. This technology can reduce CO2 emissions during converter steelmaking, achieving the goal of "carbon reduction" and turning waste into treasure.

[0004] However, due to the very short residence time of pulverized coal in the converter gasification flue, the reaction time between carbon and CO2 is also very short. Therefore, efficient reaction between carbon and CO2 is required. A key factor affecting reactivity is the particle size of the carbon; smaller carbon particles significantly increase the reaction rate. Studies have found that pulverized coal with a particle size of 200 mesh or larger has good reactivity in the gasification flue. However, current converter pulverized coal injection often directly uses pulverized coal from blast furnace injection, and the proportion of pulverized coal with a particle size larger than 200 mesh is very small. The large particle size of the pulverized coal leads to low reaction efficiency in the converter gasification flue and also results in a waste of coal resources. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides a material improvement system and method for pulverized coal injection in converter gasification flue, which aims to solve the technical problem that the high content of large particles in pulverized coal leads to low reaction efficiency of pulverized coal with CO2 in converter gasification flue and waste of coal resources.

[0006] In a first aspect, embodiments of this application provide a material improvement system for pulverized coal injection in a converter gasification flue, which is installed at the feed inlet end of the converter pulverized coal injection system. The system includes a pulverized coal injection unit, a limestone powder injection unit, and a cyclone dust collector connected to both the pulverized coal injection unit and the limestone powder injection unit. The cyclone dust collector includes a cyclone dust collector with a fine particle outlet and a coarse particle recovery outlet. The pulverized coal injected by the pulverized coal injection unit and the limestone powder injected by the limestone powder injection unit are mixed in the cyclone dust collector and separated into fine and coarse particles. The fine particles enter the converter pulverized coal injection system through the fine particle outlet, and the coarse particles are recovered and reused through the coarse particle recovery outlet.

[0007] In the technical solution of this application embodiment, by setting up a cyclone dust removal unit, large and small particles in the mixture of pulverized coal and limestone powder entering the cyclone dust collector are separated, allowing only small particles to enter the converter pulverized coal injection system for reaction, thus promoting the efficient reaction of pulverized coal and CO2 in the gasification flue. By setting up a limestone powder injection unit, pulverized coal and limestone powder are mixed simultaneously during the separation of coarse particles in the cyclone dust collector. The presence of limestone can desulfurize the flue gas in the gasification flue, and the calcium oxide generated by the high-temperature decomposition of limestone can act as a catalyst to further catalyze the reaction between pulverized coal and CO2.

[0008] In some embodiments, the cyclone dust removal unit further includes a mixing pipe disposed at the inlet end of the cyclone dust collector, and the outlets of the pulverized coal injection unit and the limestone powder injection unit are both connected to the mixing pipe; the mixing pipe is sequentially provided with a first nitrogen injection pipe, a regulating valve, and a flow meter along the material direction; the pressure inside the cyclone dust collector is 0.5-10 MPa; the flow rate of the flow meter is 40-80 m³ / h. 3 / h; The feed inlet and the fine particle outlet of the cyclone dust collector are both located at the top of the cyclone dust collector.

[0009] In the technical solution of this application embodiment, a first nitrogen injection pipe is provided to supply power and nitrogen atmosphere for the mixture of pulverized coal and limestone powder to enter the cyclone dust collector. A regulating valve and flow meter are used to ensure the flow of the mixture entering the cyclone dust collector is within a preset range. By positioning the feed inlet and fine particle outlet of the cyclone dust collector at the top, it is convenient to eject the fine particle stream from the fine particle outlet.

[0010] In some embodiments, the coarse particle recovery port is provided with a return dust pipe and a large particle storage bin connected to the return dust pipe; the coarse particle recovery port is located at the bottom of the cyclone dust collector.

[0011] In the technical solution of this application embodiment, by setting up a return dust pipe and a large particle storage bin, it is convenient to recover and temporarily store the coarse particles separated by the cyclone dust collector in the large particle storage bin. By setting the coarse particle recovery port at the bottom of the cyclone dust collector, it is convenient for the settled coarse particles to be sprayed out from the coarse particle recovery port.

[0012] In some embodiments, the limestone powder injection unit includes a limestone powder silo and a second drying gas injection pipe disposed on the limestone powder silo; the gas delivered by the second drying gas injection pipe is nitrogen or compressed air.

[0013] In the technical solution of this application embodiment, by setting a second drying gas injection pipe, the limestone powder is dried while providing power for the limestone powder to enter the cyclone dust collector.

[0014] In some embodiments, a receiving bag is provided at one end of the return powder pipe near the coarse particle recovery port, the inlet of the receiving bag is connected to the coarse particle recovery port, and the outlet of the receiving bag is connected to the inlet of the return powder pipe; a first negative pressure fan is connected to the receiving bag.

[0015] In the technical solution of this application embodiment, a receiving bag is set up to collect and temporarily store the sprayed coarse particles, preventing excessive coarse particles from clogging the coarse particle collection port and the return powder pipe. By setting up a first negative pressure fan, the receiving bag is kept under negative pressure, which promotes the coarse particles to enter the receiving bag and then enter the large particle storage bin through the return powder pipe.

[0016] In some embodiments, the pulverized coal injection unit includes a crusher, a coal mill, a coal outlet pipe, and a pulverized coal silo connected in sequence; the coal mill is provided with a first drying gas injection pipe, and the gas transported by the first drying gas injection pipe is nitrogen or compressed air.

[0017] In the technical solution of this application embodiment, the raw coal is initially crushed by setting a crusher, and the raw coal is further refined into coal powder by setting a coal mill. The coal powder is dried by setting a first drying gas injection pipe, which provides power for the coal powder to enter the cyclone dust collector.

[0018] In some embodiments, the pulverized coal silo is equipped with a bag filter, the bag filter is equipped with a second negative pressure fan, and the inlet end of the bag filter is equipped with a filter screen.

[0019] In the technical solution of this application embodiment, by setting up a bag filter and a second negative pressure fan, some of the gas in the coal powder silo is extracted to ensure the nitrogen atmosphere in the cyclone dust collector. By setting up a filter screen, the coal powder in the coal powder silo is prevented from being drawn into the bag filter.

[0020] In some embodiments, the pressure of the gas delivered by the second drying gas injection pipe is greater than the pressure of the gas delivered by the first drying gas injection pipe.

[0021] In the technical solution of this application embodiment, by controlling the gas delivered by the second drying gas injection pipe and the first drying gas injection pipe, the amount of limestone powder and coal powder injected is controlled within a preset ratio range, which facilitates the smooth and efficient progress of the subsequent reduction reaction.

[0022] Secondly, embodiments of this application provide a method for improving the pulverized coal injection material in a converter gasification flue, implemented using the pulverized coal injection material improvement system for a converter gasification flue provided in the first aspect of this application, comprising the following steps:

[0023] S1. Coal powder is injected from the coal powder injection unit into the cyclone dust collector unit, and limestone powder is injected from the limestone powder injection unit into the cyclone dust collector unit at the same time.

[0024] S2. Coal powder and limestone powder are mixed and separated in the cyclone dust collector into a fine-particle airflow containing fine particles and a coarse-particle airflow containing coarse particles. The fine-particle airflow enters the converter pulverized coal injection system through the fine-particle nozzle, and the coarse-particle airflow is recycled through the coarse-particle recovery port.

[0025] In the technical solution of this application embodiment, by utilizing a specific converter gasification flue pulverized coal injection material improvement system, the particle size of the material entering the converter pulverized coal injection system is refined, thereby improving the reaction rate and efficiency of the subsequent reduction reaction.

[0026] In some embodiments, in step S1, the mass of limestone powder injected by the limestone powder injection unit accounts for 1%-30% of the mass of coal powder injected by the coal powder injection unit; the proportion of limestone powder with a particle size of 200-300 mesh is 60%-75%; and the proportion of coal powder with a particle size greater than 200 mesh is 60%-75%.

[0027] In step S2, the proportion of fine particles with a particle size of 200 mesh or larger in the fine particulate airflow is 90%-98%.

[0028] In the technical solution of this application embodiment, by controlling the particle size and addition ratio of pulverized coal and limestone powder, the content of pulverized coal and the particle size of fine particles in the fine particle stream ejected from the fine particle nozzle are controlled, thereby improving the reaction rate and reaction efficiency of the subsequent reduction reaction.

[0029] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0031] Figure 1 This is a schematic diagram of the improved material system for pulverized coal injection in the converter gasification flue of this application embodiment;

[0032] Figure 2 This is the particle size distribution curve of the fine particles entering the converter pulverized coal injection system through the fine particle injection outlet in Embodiment 1 of this application;

[0033] Figure 3 This is the particle size distribution curve of fine particles entering the converter pulverized coal injection system through the fine particle injection outlet in Comparative Example 1 of this application.

[0034] Explanation of reference numerals in the attached diagram: 100-Pulverized coal injection material improvement system for converter gasification flue; 1-Pulverized coal injection unit; 2-Limestone powder injection unit; 3-Cyclone dust collector unit; 4-Return powder pipe; 5-First receiving bag; 6-First negative pressure fan; 7-Second nitrogen injection pipe; 8-Converter pulverized coal injection system; 9-Conveying pipe; 10-Large particle storage bin; 11-Crusher; 12-Pulverizer; 13-Coal outlet pipe; 14-Pulverized coal bin; 15-First drying gas injection pipe; 16-Bag filter; 17-Conveyor belt; 21-Limestone powder bin; 22-Second drying gas injection pipe; 31-Cyclone dust collector; 32-Fine particle outlet; 33-Coarse particle recovery port; 34-Mixing pipe; 35-First nitrogen injection pipe; 36-Regulating valve; 37-Flow meter. Detailed Implementation

[0035] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0037] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0038] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0039] In the description of the embodiments of this application, the technical terms "top" and "bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0040] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0041] The existing blast furnace pulverized coal injection system directly feeds pulverized coal into the converter pulverized coal injection system after it has been processed by a mill. The content of large particles in the pulverized coal is relatively high. The presence of large pulverized coal particles affects the reaction efficiency of pulverized coal with CO2 in the converter gasification flue, resulting in low reaction efficiency between carbon and CO2. At the same time, large particles do not participate in the reaction, resulting in a waste of coal resources.

[0042] To address the technical problem of low reaction efficiency and coal resource waste caused by the high content of large particles in pulverized coal in the converter gasification flue, this application provides an improved system and method for pulverized coal injection in the converter gasification flue. This system adds a cyclone dust collector unit to the existing blast furnace pulverized coal injection system, introducing pulverized coal into the cyclone dust collector for processing. Simultaneously, a limestone powder injection unit is added, using the cyclone dust collector to separate large and small particles in the pulverized coal and limestone powder mixture, allowing only small particles to enter the converter pulverized coal injection system. This optimizes the particle size of the pulverized coal and limestone powder entering the converter pulverized coal injection system, improves the reaction kinetics, and increases the reaction efficiency of carbon and CO2 in the converter flue gas after pulverized coal injection. This achieves efficient conversion of pulverized coal in the flue, reduces coal resource waste, and, under the current trend of low-carbon metallurgy, reduces carbon emissions, improves production efficiency, and lowers production costs.

[0043] Please refer to Figure 1 In a first aspect, embodiments of this application provide a material improvement system 100 for pulverized coal injection in a converter gasification flue, which is installed at the feed inlet end of the converter pulverized coal injection system 8. It includes a pulverized coal injection unit 1, a limestone powder injection unit 2, and a cyclone dust removal unit 3 connected to both the pulverized coal injection unit 1 and the limestone powder injection unit 2. The cyclone dust removal unit 3 includes a cyclone dust collector 31, which is provided with a fine particle spray outlet 32 ​​and a coarse particle recovery outlet 33. Specifically, the pulverized coal flow injected by the pulverized coal injection unit 1 and the limestone powder flow injected by the limestone powder injection unit 2 simultaneously enter the cyclone dust collector unit 3, where they are mixed and separated into a fine-particle airflow containing fine particles and a coarse-particle airflow containing coarse particles (both fine and coarse particles are mixtures of pulverized coal and limestone powder, with different proportions of pulverized coal and limestone powder). The fine-particle airflow then enters the converter pulverized coal injection system 8 through the fine-particle outlet 32, and then enters the gasification flue through the converter pulverized coal injection system 8. The pulverized coal in the fine-particle airflow reacts efficiently with CO2 in the gasification flue, reducing CO2 to CO. At the same time, the limestone powder in the fine-particle airflow desulfurizes the flue gas in the gasification flue, and the calcium oxide generated by the high-temperature decomposition of limestone can further catalyze the reaction between pulverized coal and CO2. The coarse-particle airflow is recovered and reused through the coarse-particle recovery port 33.

[0044] In the technical solution of this application embodiment, by adding a cyclone dust removal unit 3 to the existing blast furnace pulverized coal injection system, the characteristics of the cyclone dust collector 31 in separating large and small particles are utilized. This allows large and small particles in the pulverized coal and limestone powder mixture entering the cyclone dust collector 31 to be separated, so that only small particles enter the converter pulverized coal injection system 8. This increases the proportion of small particles in the mixture entering the converter pulverized coal injection system 8 (mainly increasing the proportion of small pulverized coal particles), thereby promoting the efficient reaction of pulverized coal and CO2 in the gasification flue, improving the reaction efficiency and reaction rate, and resulting in high pulverized coal utilization. Consequently, the CO content in the flue gas after the reaction is high, and the flue gas quality is high. By adding a limestone powder injection unit 2, the limestone powder flow and the coal powder flow enter the cyclone dust collector unit 3 simultaneously for mixing. On the one hand, the larger airflow velocity in the cyclone dust collector 31 makes the limestone powder and coal powder mix more evenly; at the same time, it causes the limestone powder and coal powder to collide, avoiding the agglomeration of small coal powder and limestone powder particles. Moreover, the mutual collision between different powders can further refine the particle size of coal powder and limestone powder, increasing the proportion of fine particles. On the other hand, the presence of limestone can desulfurize the flue gas in the gasification flue, and the calcium oxide generated by the high-temperature decomposition of limestone can act as a catalyst to further catalyze the reaction between coal powder and CO2.

[0045] Furthermore, in some embodiments, the cyclone dust removal unit 3 further includes a mixing pipe 34 disposed at the inlet end of the cyclone dust collector 31, and the outlets of the pulverized coal injection unit 1 and the limestone powder injection unit 2 are both connected to the mixing pipe 34; the mixing pipe 34 is sequentially provided with a first nitrogen injection pipe 35, a regulating valve 36, and a flow meter 37 along the material direction; the pressure inside the cyclone dust collector 31 is 0.5-10 MPa; the flow rate of the flow meter 37 is 40-80 m³ / h. 3 / h (i.e., the flow rate of the mixture of nitrogen flow, pulverized coal flow, and limestone powder flow); the feed inlet and fine particle outlet 32 ​​of the cyclone dust collector 31 are both located at the top of the cyclone dust collector 31. Specifically, the pressure inside the cyclone dust collector 31 is jointly determined by the nitrogen flow injected into the first nitrogen injection pipe 35, the pulverized coal flow injected into the pulverized coal injection unit 1, and the limestone powder flow injected into the limestone powder injection unit 2.

[0046] In the technical solution of this application embodiment, by setting a mixing pipe 34 at the feed inlet end of the cyclone dust collector 31, the coal powder flow ejected from the coal powder injection unit 1 and the limestone powder flow ejected from the limestone powder injection unit 2 are initially mixed and collided in the mixing pipe 34. At the same time, the pipe wall of the mixing pipe 34 can also promote the effective collision of coal powder and limestone powder, providing favorable conditions for further mixing and collision of coal powder and limestone powder in the cyclone dust collector 31. By setting a first nitrogen injection pipe 35, nitrogen gas enters the mixing pipe 34 through the first nitrogen injection pipe 35, and then enters the cyclone dust collector 31. The presence of nitrogen gas flow provides power for the mixture of coal powder and limestone powder to enter the cyclone dust collector 31, and the nitrogen gas flow can promote the uniform mixing of coal powder and limestone powder; at the same time, it ensures the high pressure and nitrogen atmosphere in the cyclone dust collector 31, thereby ensuring the inert atmosphere of the fine particle flow ejected from the fine particle outlet 32, avoiding subsequent oxidation of flue gas. A regulating valve 36 is used to adjust the flow rate of the mixed material flow (i.e., the mixture of nitrogen flow, coal powder flow, and limestone powder flow) entering the cyclone dust collector 31. A flow meter 37 is used to monitor the airflow velocity and flow rate of the mixed material flow entering the cyclone dust collector 31 in real time and accurately. Through the coordinated action of the regulating valve 36 and the flow meter 37, the mixed material flow entering the cyclone dust collector 31 is kept within a preset range. The pressure inside the cyclone dust collector 31 is set to a high pressure of 0.5-10 MPa. This high pressure facilitates the effective mixing and collision of coal powder and limestone powder, and also promotes the outflow of both fine and coarse particles. By placing the feed inlet and fine particle outlet 32 ​​of the cyclone dust collector 31 at the top, it is convenient to eject the fine particle flow from the fine particle outlet 32, while providing sufficient space for the settling of coarse particles.

[0047] Furthermore, in some embodiments, a conveying pipe 9 and a second receiving bag (not shown in the figure) are provided between the fine particle injection outlet 32 ​​and the converter pulverized coal injection system 8, and a third nitrogen injection pipe (not shown in the figure) is provided at one end of the conveying pipe 9 near the fine particle injection outlet 32.

[0048] In the technical solution of this application embodiment, a conveying pipe 9 is provided to facilitate the transport of the fine particle stream ejected from the fine particle nozzle 32 to the converter pulverized coal injection system 8. A second receiving bag is provided to temporarily store the fine particle stream when the flow rate of the fine particle stream ejected from the fine particle nozzle 32 is too large, and then send it to the converter pulverized coal injection system 8. A third nitrogen injection pipe is provided to provide power for the fine particle stream to smoothly enter the converter pulverized coal injection system 8, while further ensuring the nitrogen atmosphere of the fine particle stream entering the converter pulverized coal injection system 8.

[0049] Furthermore, in some embodiments, a return dust pipe 4 and a large particle storage bin 10 connected to the return dust pipe 4 are provided at the coarse particle recovery port 33; the coarse particle recovery port 33 is located at the bottom of the cyclone dust collector 31. Specifically, the coarse particles ejected through the coarse particle recovery port 33 enter the large particle storage bin 10 for temporary storage through the return dust pipe 4, and the coarse particles in the large particle storage bin 10 are injected into the blast furnace for direct use.

[0050] In the technical solution of this application embodiment, by setting a return powder pipe 4 and a large particle storage bin 10 at the coarse particle recovery port 33, it is convenient to transport the coarse particles separated by the cyclone dust collector 31 to the large particle storage bin 10. By setting the coarse particle recovery port 33 at the bottom of the cyclone dust collector 31, it is convenient for the settled coarse particles to be sprayed out from the coarse particle recovery port 33.

[0051] Further, in some embodiments, the limestone powder injection unit 2 includes a limestone powder silo 21 and a second dry gas injection pipe 22 disposed on the limestone powder silo 21; the gas delivered by the second dry gas injection pipe 22 is nitrogen or compressed air. Specifically, after the limestone powder is ground to a uniform fineness, it is poured into the limestone powder silo 21, and the nitrogen or compressed air injected through the second dry gas injection pipe 22 enters the mixing pipe 34, and then enters the cyclone dust collector 31. When the gas delivered in the second dry gas injection pipe 22 is a mixture of nitrogen and compressed air or compressed air, since the first nitrogen injection pipe 35 ejects a large amount of nitrogen and the mixing pipe 34 is long enough, the small amount of compressed air delivered by the second dry gas injection pipe 22 will not affect the nitrogen atmosphere in the cyclone dust collector 31.

[0052] In the technical solution of this application embodiment, by setting a second drying gas injection pipe 22, dry nitrogen or compressed air is injected into the limestone powder silo 21, which can dry the limestone powder and prevent agglomeration; on the other hand, it provides power for the limestone powder to enter the cyclone dust collector 31.

[0053] Furthermore, in some embodiments, a receiving bag 5 is provided at one end of the return powder pipe 4 near the coarse particle recovery port 33. The inlet of the receiving bag 5 is connected to the coarse particle recovery port 33, and the outlet of the receiving bag 5 is connected to the inlet of the return powder pipe 4. A first negative pressure fan 6 is connected to the receiving bag 5.

[0054] In the technical solution of this application embodiment, a receiving bag 5 is installed between the coarse particle recovery port 33 and the return powder pipe 4 to recover and temporarily store the coarse particles ejected from the coarse particle recovery port 33, preventing excessive coarse particles from clogging the coarse particle recovery port 33 and the return powder pipe 4. A first negative pressure fan 6 is connected to the receiving bag 5, which keeps the receiving bag 5 under negative pressure, creating a large pressure difference between the cyclone dust collector 31 and the receiving bag 5. Under the synergistic effect of the high pressure of the cyclone dust collector 31 and the negative pressure of the receiving bag 5, the coarse particles settling in the cyclone dust collector 31 are promoted to enter the receiving bag 5. Simultaneously, the continuous high pressure of the cyclone dust collector 31 allows the coarse particles in the receiving bag 5 to smoothly enter the large particle storage bin 10 through the return powder pipe 4.

[0055] Furthermore, in some embodiments, a second nitrogen injection pipe 7 is provided at one end of the return powder pipe 4 near the receiving bag 5.

[0056] In the technical solution of this application embodiment, by setting a second nitrogen injection pipe 7 at one end of the return powder pipe 4 near the receiving bag 5, the power is further provided for the coarse particles to smoothly enter the large particle storage bin 10, while ensuring the nitrogen atmosphere in the return powder pipe 4.

[0057] Furthermore, in some embodiments, the pulverized coal injection unit 1 includes a crusher 11, a coal mill 12, a coal outlet pipe 13, and a pulverized coal silo 14 connected in sequence; the coal mill 12 is provided with a first drying gas injection pipe 15, and the gas transported by the first drying gas injection pipe 15 is nitrogen or compressed air. Specifically, the coal mill 12 is a bowl mill. When the gas transported in the first drying gas injection pipe 15 is a mixture of nitrogen and compressed air or compressed air, since the first nitrogen injection pipe 35 sprays out a large amount of nitrogen, and the mixing pipe 34 is long enough, the small amount of compressed air transported by the first drying gas injection pipe 15 will not affect the nitrogen atmosphere in the cyclone dust collector 31.

[0058] In the technical solution of this application embodiment, the raw coal is initially crushed by a crusher 11, and then the initially crushed raw coal is placed in a coal mill 12 for grinding, so that the raw coal is further refined into coal powder. At the same time, the bowl mill can also dry the coal powder. By setting a first drying gas injection pipe 15 on the coal mill 12, the coal powder is further dried while providing power for the coal powder to smoothly enter the cyclone dust collector 31.

[0059] Furthermore, in some embodiments, a conveyor belt 17 is provided at the feed inlet end of the crusher 11 and between the crusher 11 and the coal mill 12.

[0060] In the technical solution of the embodiments of the present application, by arranging the conveyor belt 17 at the feed inlet end of the crusher 11 and between the crusher 11 and the coal mill 12, the transportation of raw coal and preliminarily crushed raw coal is facilitated.

[0061] Further, in some embodiments, a bag-type dust collector 16 is arranged on the pulverized coal bin 14, a second negative pressure fan is arranged in the bag-type dust collector 16, and a filter screen is arranged at the feed inlet end of the bag-type dust collector 16.

[0062] In the technical solution of the embodiments of the present application, by arranging the bag-type dust collector 16 and the second negative pressure fan, part of the gas in the pulverized coal bin 14 is extracted, which reduces the content of compressed air entering the mixing pipe 34, ensures the nitrogen atmosphere in the cyclone dust collector 31, and does not affect the smooth injection of pulverized coal in the pulverized coal bin 14. By arranging the filter screen, the pulverized coal in the pulverized coal bin 14 is prevented from being extracted into the bag-type dust collector 16.

[0063] Further, in some embodiments, the pressure of the gas conveyed by the second drying gas injection pipe 22 is higher than the pressure of the gas conveyed by the first drying gas injection pipe 15.

[0064] In the technical solution of the embodiments of the present application, according to the characteristic that the density of limestone powder is higher than that of pulverized coal, by setting the pressure of the gas conveyed by the second drying gas injection pipe 22 to be higher than that of the gas conveyed by the first drying gas injection pipe 15, while ensuring the smooth injection of limestone powder and pulverized coal, the injection amounts of limestone powder and pulverized coal are controlled within a preset proportional range, which facilitates the smooth and efficient progress of the subsequent reduction reaction.

[0065] In a second aspect, an embodiment of the present application provides a material improvement method for coal injection in a converter vaporization flue, which is implemented by using the above material improvement system for coal injection in a converter vaporization flue, and includes the following steps:

[0066] S1, after raw coal is preliminarily crushed by the crusher 11, it is conveyed to the coal mill 12 for grinding through the conveyor belt 17, nitrogen or compressed air is conveyed through the first drying gas injection pipe 15, the ground pulverized coal and airflow enter the pulverized coal bin 14 through the coal outlet pipe 13, the bag-type dust collector 16 extracts part of the gas in the pulverized coal flow from the pulverized coal bin 14, and the remaining pulverized coal flow enters the mixing pipe 34.

[0067] At the same time, after grinding the limestone powder to a uniform fineness, pour it into the limestone powder bin 21, and convey nitrogen or compressed air through the second drying gas injection pipe 22, and the limestone powder and airflow form a limestone powder flow into the mixing pipe 34.

[0068] S2. Nitrogen gas is injected into the mixing pipe 34 through the first nitrogen injection pipe 35. The coal powder flow, limestone powder flow, and nitrogen flow are initially mixed and collided in the mixing pipe 34 before entering the cyclone dust collector 31. At the same time, the airflow velocity and flow rate of the mixed material flow entering the cyclone dust collector 31 are controlled by the regulating valve 36 and the flow meter 37. The coal powder and limestone powder are further mixed and collided in the cyclone dust collector 31. After separation by the cyclone dust collector 31, the coarse particles in the coarse particle flow (a mixture of large coal powder particles, large limestone powder particles, and a small amount of gas) settle at the bottom of the cyclone dust collector 31 and enter the return pipe 4 through the coarse particle recovery port 33 and then enter the large particle storage bin 10. The fine particle flow (a mixture of small coal powder particles, small limestone powder particles, and a large amount of gas) enters the converter pulverized coal injection system 8 through the fine particle injection port 32 for subsequent reduction reaction.

[0069] In the technical solution of this application embodiment, by utilizing a specific converter gasification flue pulverized coal injection material improvement system, the particle size of the material entering the converter pulverized coal injection system 8 is refined, thereby improving the reaction rate and efficiency of the subsequent reduction reaction.

[0070] Furthermore, in some embodiments, in step S1, the mass of limestone powder injected by limestone powder injection unit 2 accounts for 1%-30% of the mass of coal powder injected by coal powder injection unit 1; the proportion of limestone powder with a particle size of 200-300 mesh is 60%-75% (in terms of volume percentage); and the proportion of coal powder with a particle size greater than 200 mesh is 60%-75% (in terms of volume percentage).

[0071] In step S2, the proportion of fine particles with a size of 200 mesh or larger in the fine particulate airflow is 90%-98% (referring to the volume percentage).

[0072] In the technical solution of this application embodiment, by controlling the particle size and addition ratio of coal powder and limestone powder, the content of coal powder and the particle size of fine particles in the fine particle stream ejected from the fine particle ejection outlet 32 ​​are controlled, thereby improving the reaction rate and reaction efficiency of the subsequent reduction reaction.

[0073] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0074] Example 1

[0075] A method for improving the material used for pulverized coal injection in a converter gasification flue includes the following steps:

[0076] S1. After the raw coal is initially crushed by the crusher 11, it is conveyed to the coal mill 12 for grinding by the conveyor belt 17, and nitrogen is conveyed through the first dry gas injection pipe 15. The ground coal powder and gas flow enter the coal powder silo 14 through the coal outlet pipe 13. The bag filter 16 extracts part of the gas in the coal powder flow in the coal powder silo 14, and the remaining coal powder flow enters the mixing pipe 34.

[0077] Meanwhile, after the limestone powder is ground to a uniform fineness, it is poured into the limestone powder silo 21, and nitrogen is delivered through the second drying gas injection pipe 22. The limestone powder and the airflow form a limestone powder flow that enters the mixing pipe 34.

[0078] The limestone powder injected by limestone powder injection unit 2 accounts for 10% of the total mass of coal powder injected by coal powder injection unit 1; 70% of the limestone powder has a particle size of 200-300 mesh; 70% of the coal powder has a particle size greater than 200 mesh; and the flow rate of flow meter 37 is 40 m³ / s. 3 / h.

[0079] S2. Nitrogen gas is injected into the mixing pipe 34 through the first nitrogen injection pipe 35. The coal powder flow, limestone powder flow, and nitrogen flow are initially mixed and collided in the mixing pipe 34 before entering the cyclone dust collector 31. At the same time, the airflow velocity and flow rate of the mixed material flow entering the cyclone dust collector 31 are controlled by the regulating valve 36 and the flow meter 37. The coal powder and limestone powder are further mixed and collided in the cyclone dust collector 31. After separation by the cyclone dust collector 31, the coarse particles in the coarse particle flow settle at the bottom of the cyclone dust collector 31 and enter the return pipe 4 through the coarse particle recovery port 33 and then enter the large particle storage bin 10. The fine particle flow enters the converter pulverized coal injection system 8 through the fine particle injection port 32 for subsequent reduction reaction.

[0080] Among them, the converter pulverized coal injection system 8 is a 120t converter of a steel plant. The working pressure of the cyclone dust collector 31 is 0.5Mpa.

[0081] In Example 1, fine particles entering the converter pulverized coal injection system 8 through fine particle outlet 32 ​​were sampled and their particle size was analyzed. The specific analysis process was as follows: a small amount of fine particles were dispersed by using an alcohol wet method, and then the particle size of the sample was measured by a laser particle size analyzer. The instrument converted the measurement data into a particle size distribution curve.

[0082] Particle size analysis results are as follows Figure 2 As shown, from Figure 2 From the differential distribution curve, it can be seen that there are significantly more fine particles with a particle size greater than 200 mesh in the fine particles entering the converter pulverized coal injection system 8. At the same time, from the cumulative distribution curve, it can be seen that the fine particles with a particle size greater than 200 mesh account for about 95% of the total.

[0083] Examples 2-4

[0084] An improved method for pulverized coal injection in a converter gasification flue differs from Example 1 in that the flow rate of flow meter 37 is different, while the rest is largely the same as Example 1 and will not be described in detail here.

[0085] Fine particles entering the converter pulverized coal injection system 8 through the fine particle injection outlet 32 ​​in Examples 1-4 were sampled and their particle size was analyzed. The particle size distribution curves obtained from the laser particle size analyzer were summarized and calculated, and the results are shown in Table 1. Here, 74 μm is equivalent to 200 mesh.

[0086] Table 1. Particle size analysis results of fine particles in Examples 1-4

[0087]

[0088] As shown in Table 1, in Example 1, 95% of the fine particles were larger than 200 mesh; in Example 2, 88% were larger than 200 mesh; in Example 3, 82% were larger than 200 mesh; and in Example 4, 98% were larger than 200 mesh. This indicates that as the flow rate of flowmeter 37 increases, the proportion of fine particles larger than 200 mesh entering the converter pulverized coal injection system 8 gradually decreases. This may be because as the flow rate of flowmeter 37 increases, the larger flow rate will affect the settling of coarse particles in the cyclone dust collector 31 to some extent, thus affecting the proportion of fine particles in the fine particles entering the converter pulverized coal injection system 8. Conversely, if the flow rate of flowmeter 37 is too low, it will also affect the mixing and separation of coarse and fine particles in the cyclone dust collector 31.

[0089] In addition, in Examples 1-4, the fine particles of coal powder and limestone powder were mixed more evenly.

[0090] Examples 5-7

[0091] An improved method for pulverized coal injection in a converter gasification flue differs from Example 1 in that the mass fraction of limestone powder injected by limestone powder injection unit 2 relative to the mass fraction of pulverized coal injected by pulverized coal injection unit 1 is different. Otherwise, it is largely the same as Example 1 and will not be repeated here.

[0092] The fine particles that entered the converter pulverized coal injection system 8 through the fine particle injection outlet 32 ​​in Examples 5-7 were sampled and their particle size was analyzed. The data of the particle size distribution curve obtained by the laser particle size analyzer were summarized and calculated, and the results are shown in Table 2.

[0093] Table 2. Particle size analysis results of fine particles in Examples 5-7

[0094]

[0095] As shown in Table 2, with the increase of limestone powder addition, the proportion of fine particles in the fine particles entering the converter pulverized coal injection system 8 gradually decreases. This indicates that the presence of limestone can, to some extent, alter the interaction between different particles in the cyclone dust collector 31, thereby affecting the proportion of fine particles in the fine particles entering the converter pulverized coal injection system 8. However, when the amount of limestone powder added varies within a certain range, the proportion of fine particles in the fine particles entering the converter pulverized coal injection system 8 is relatively high, and the overall effect is relatively good. When the mass of limestone powder injected by limestone powder injection unit 2 accounts for 5% of the mass of pulverized coal injected by pulverized coal injection unit 1, the proportion of particles with a size greater than 200 mesh in the fine particle size reaches as high as 96%. In addition, in Examples 5-7, the fine particles are relatively uniformly mixed with pulverized coal and limestone powder.

[0096] Comparative Example 1

[0097] An improved method for pulverized coal injection in a converter gasification flue, employing traditional injection methods, omitting the limestone powder injection unit 2 and cyclone dust removal unit 3, with the pulverized coal silo 14's outlet directly connected to the converter pulverized coal injection system 8, includes the following steps:

[0098] After the raw coal is initially crushed by the crusher 11, it is conveyed to the coal mill 12 for grinding via the conveyor belt 17. Nitrogen is also introduced through the first dry gas injection pipe 15. The ground coal powder and gas flow enter the coal powder silo 14 through the coal outlet pipe 13. The bag filter 16 extracts part of the gas from the coal powder flow in the coal powder silo 14. The remaining coal powder flow enters the converter pulverized coal injection system 8 for subsequent reduction reaction.

[0099] In this case, 70% of the pulverized coal had a particle size greater than 200 mesh, the same as in Example 1. The converter pulverized coal injection system 8 is a 120t converter in a steel plant.

[0100] Fine particles from Comparative Example 1, which entered the converter pulverized coal injection system 8 through fine particle outlet 32, were sampled and their particle size was analyzed. The particle size analysis results are as follows: Figure 3 As shown, from Figure 3 From the differential distribution curve, it can be seen that the proportion of fine particles with a size larger than 200 mesh in the fine particles entering the converter pulverized coal injection system 8 is extremely small. Meanwhile, from the cumulative distribution curve, the proportion of fine particles with a size larger than 200 mesh is about 70% of the total, which is basically consistent with the proportion of pulverized coal particles larger than 200 mesh being 70%. As can be seen from the particle size distribution diagrams of Example 1 and Comparative Example 1, compared with the traditional process, the method of this invention significantly refines the particle size of the fine particles entering the converter pulverized coal injection system 8, achieving efficient conversion of pulverized coal in the flue.

[0101] Comparative Example 2

[0102] An improved method for pulverized coal injection in a converter gasification flue differs from Example 1 in that it does not include a limestone powder injection unit 2, meaning the mass percentage of limestone powder is 0. Otherwise, it is largely the same as Example 1 and will not be described further here.

[0103] Fine particles entering the converter pulverized coal injection system 8 through the fine particle injection outlet 32 ​​in Comparative Examples 1-2 were sampled and their particle size was analyzed. The data of the particle size distribution curve obtained by the laser particle size analyzer were summarized and calculated, and the results are shown in Table 3.

[0104] Table 3. Particle size analysis results of fine particles in Comparative Examples 1-2

[0105]

[0106] As shown in Table 3, if the traditional injection method in Comparative Example 1 is used, the proportion of fine particles larger than 200 mesh in the pulverized coal entering the converter pulverized coal injection system 8 is about 70%. This is basically consistent with the fact that the proportion of pulverized coal particles larger than 200 mesh is 70%. This further illustrates that compared with the traditional process, the method of the present invention significantly refines the particle size of the fine particles entering the converter pulverized coal injection system 8, and achieves efficient conversion of pulverized coal in the flue.

[0107] If the injection method of Comparative Example 2 is used, the proportion of fine particles with a particle size greater than 200 mesh entering the converter pulverized coal injection system 8 is 92%, which is slightly worse than 95% in Example 1. This further illustrates that the presence of limestone promotes the separation of coarse and fine particles to a certain extent.

[0108] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A material improvement system for pulverized coal injection in a converter gasification flue, installed at the feed inlet end of the converter pulverized coal injection system, characterized in that, The system includes a pulverized coal injection unit, a limestone powder injection unit, and a cyclone dust collector connected to both the pulverized coal injection unit and the limestone powder injection unit. The cyclone dust collector includes a cyclone dust collector with a fine particle outlet and a coarse particle recovery port. The pulverized coal injected by the pulverized coal injection unit and the limestone powder injected by the limestone powder injection unit are mixed and separated into fine and coarse particles in the cyclone dust collector. The fine particles enter the converter pulverized coal injection system through the fine particle outlet, and the coarse particles are recovered and reused through the coarse particle recovery port.

2. The material improvement system for pulverized coal injection in the converter gasification flue according to claim 1, characterized in that, The cyclone dust removal unit also includes a mixing pipe located at the inlet of the cyclone dust collector. The outlets of both the pulverized coal injection unit and the limestone powder injection unit are connected to the mixing pipe. The mixing pipe is sequentially equipped with a first nitrogen injection pipe, a regulating valve, and a flow meter along the material flow direction. The pressure inside the cyclone dust collector is 0.5-10 MPa; the flow rate of the flow meter is 40-80 m³ / h. 3 / h; The feed inlet and the fine particle outlet of the cyclone dust collector are both located at the top of the cyclone dust collector.

3. The material improvement system for pulverized coal injection in the converter gasification flue according to claim 2, characterized in that, The coarse particle recovery port is equipped with a return dust pipe and a large particle storage bin connected to the return dust pipe; the coarse particle recovery port is located at the bottom of the cyclone dust collector.

4. The material improvement system for pulverized coal injection in the converter gasification flue according to claim 3, characterized in that, The limestone powder injection unit includes a limestone powder silo and a second drying gas injection pipe disposed on the limestone powder silo; the gas delivered by the second drying gas injection pipe is nitrogen or compressed air.

5. The material improvement system for pulverized coal injection in the converter gasification flue according to claim 4, characterized in that, A material collection bag is provided at one end of the return powder pipe near the coarse particle recovery port. The inlet of the material collection bag is connected to the coarse particle recovery port, and the outlet of the material collection bag is connected to the inlet of the return powder pipe. A first negative pressure fan is connected to the material collection bag.

6. The material improvement system for pulverized coal injection in the converter gasification flue according to claim 5, characterized in that, The pulverized coal injection unit includes a crusher, a coal mill, a coal outlet pipe, and a pulverized coal silo connected in sequence; the coal mill is equipped with a first drying gas injection pipe, and the gas transported by the first drying gas injection pipe is nitrogen or compressed air.

7. The material improvement system for pulverized coal injection in the converter gasification flue according to claim 6, characterized in that, The pulverized coal silo is equipped with a bag filter, which contains a second negative pressure fan and a filter screen at the feed inlet.

8. The material improvement system for pulverized coal injection in the converter gasification flue according to claim 7, characterized in that, The pressure of the gas delivered by the second drying gas injection pipe is greater than the pressure of the gas delivered by the first drying gas injection pipe.

9. A method for improving the pulverized coal injection material in a converter gasification flue, implemented using the pulverized coal injection material improvement system according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Coal powder is injected from the coal powder injection unit into the cyclone dust collector unit, and limestone powder is injected from the limestone powder injection unit into the cyclone dust collector unit at the same time. S2. Coal powder and limestone powder are mixed and separated in the cyclone dust collector into a fine particle airflow containing fine particles and a coarse particle airflow containing coarse particles. The fine particle airflow enters the converter pulverized coal injection system through the fine particle injection outlet, and the coarse particle airflow is recycled through the coarse particle recovery port.

10. The material improvement system for pulverized coal injection in the converter gasification flue according to claim 9, characterized in that, In step S1, the mass of limestone powder injected by the limestone powder injection unit accounts for 1%-30% of the mass of coal powder injected by the coal powder injection unit; the proportion of limestone powder with a particle size of 200-300 mesh is 60%-75%; and the proportion of coal powder with a particle size greater than 200 mesh is 60%-75%. In step S2, the proportion of fine particles with a particle size of 200 mesh or larger in the fine particulate airflow is 90%-98%.

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