A coaxial Laval narrow-sequence pulse pulverized coal injection device

Abstract

This invention discloses a coaxial sequential pulse pulverized coal injection device with a narrow-throat Laval nozzle for blast furnaces, belonging to the field of pulverized coal injection technology for blast furnace ironmaking. The device adopts a coaxial double-layer channel structure, with an inner pulverized coal channel and an outer oxygen channel. A narrow-throat Laval nozzle is installed at the end of the outer oxygen channel. The throat diameter of the Laval nozzle is 2-4.5 mm, and the axial length difference between the ends of the inner pulverized coal channel and the outer oxygen channel is 8-12 mm. An external sequential pulse control system is connected to achieve time-sharing pulsed coordinated injection of oxygen and coal. This invention improves the oxygen injection energy concentration effect through the narrow-throat Laval structure and optimizes oxygen-coal blending using specific dimensional parameters, thereby improving pulverized coal combustion efficiency. It can be widely applied to intelligent pulse pulverized coal injection systems for blast furnaces of different furnace capacities.

Description

Technical Field

[0001] This invention relates to the field of pulverized coal injection in blast furnace ironmaking, specifically a coaxial Laval narrow-phase pulse pulverized coal injection device. Background Technology

[0002] Oxygen-enriched pulverized coal injection in blast furnaces is a core process in modern ironmaking to reduce coke ratio, increase smelting intensity, and lower production costs. Currently, a large number of patents related to coaxial pulverized coal injection lances have been published in the industry. Most mainstream coaxial injection lances adopt an internal coal and external oxygen channel structure, and the nozzles are mostly ordinary straight cylinder structures. They do not have Laval energy-accelerating structures, and the outlet ends of the pulverized coal channel and the oxygen channel are basically flush. They adopt a continuous synchronous injection method.

[0003] The existing technology has obvious defects: First, it lacks a dedicated energy-accelerating structure, resulting in insufficient oxygen injection kinetic energy, incomplete mixing of pulverized coal and oxygen, and low combustion efficiency. Second, the channel layout is fixed, making it easy to fall within the scope of existing patent protection and posing a risk of infringement. Third, it lacks targeted structural size matching, making it unsuitable for pulse-type pulverized coal injection processes, resulting in poor injection stability and large fluctuations in blast furnace operating conditions.

[0004] To address the aforementioned problems, this invention employs an innovative combination of an internal coal and external oxygen reverse coaxial layout, an external oxygen channel narrow throat Laval nozzle, a specific throat size, a fixed end length difference, and sequential pulse time-sharing injection. This approach fundamentally differs from existing coaxial oxygen-coal patents in terms of channel arrangement, core nozzle structure, key dimensional parameters, and injection process, effectively circumventing existing patent barriers while improving combustion efficiency. Summary of the Invention

[0005] The technical problem to be solved by this invention is to overcome the above-mentioned technical defects.

[0006] To solve the above problems, the technical solution of the present invention is: a coaxial Laval narrow-throat pulse pulverized coal injection device, the pulse pulverized coal injection device comprising an inner pulverized coal channel and an outer oxygen channel arranged coaxially, the outer oxygen channel having a narrow-throat Laval nozzle at its end, the Laval nozzle throat diameter being 2-4.5 mm, and the axial tube length difference between the outlet end face of the inner pulverized coal channel and the outlet end face of the outer oxygen channel being 8-12 mm, the pulse... An external sequential pulse control system is connected to the pulverized coal injection unit to realize pulsed, time-sharing coordinated injection of pulverized coal and oxygen.

[0007] Furthermore, the inner pulverized coal channel is located in the center, and the outer oxygen channel covers the outer side of the inner pulverized coal channel 1 to form a double-layer coaxial structure.

[0008] Furthermore, the narrow-throat Laval nozzle is only located at the end of the external oxygen channel and is used to concentrate and accelerate oxygen.

[0009] Furthermore, the narrow-throat Laval nozzle includes an intake contraction section, a throat section, and an outlet expansion section connected in sequence. The intake contraction section is seamlessly connected to the external oxygen channel, and the inner wall of the throat section has a smooth arc transition structure.

[0010] Furthermore, the expansion angle of the outlet expansion section is 6°-12°, the throat is 2-4.5mm, the straight section should be 2-4.5mm away from the outer wall of the inner tube, that is, the diffuser section should also be 8-12mm away from the outer wall of the inner tube, so that the high-pressure oxygen expands and increases at a uniform speed after being throttled through the throat tube.

[0011] The advantages of this invention compared to existing technologies are: This invention defines optimal structural parameters and coaxial alignment, and combines them with a sequential pulse time-sharing injection control method to achieve precise coordinated injection of pulverized coal and oxygen. The high-speed oxygen layer can completely envelop the central pulverized coal jet, improving the uniformity of medium mixing by more than 30%, resulting in complete pulverized coal combustion and a high burnout rate. The narrow-throat Laval structure provides excellent oxygen focusing effect, stable oxygen jet velocity, and strong penetration. The coaxial misaligned outlet structure completely solves the problems of coal accumulation, wall adhesion, and blockage at the nozzle, significantly improving the operational stability of the device and enabling it to be adapted to long-term industrial intermittent pulse combustion, high-temperature heating, and pulse ignition conditions. Attached Figure Description

[0012] Figure 1 is a schematic diagram of the structure of a coaxial Laval narrow-sequence pulse pulverized coal injection device according to the present invention.

[0013] As shown in the figure: 1. Internal pulverized coal channel; 2. External oxygen channel. Detailed Implementation

[0014] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. The same components are referred to as... The same reference numerals are used in the accompanying drawings.

[0015] It should be noted that the terms “front,” “back,” “left,” “right,” “up,” and “down” used in the following description refer to the directions shown in the attached diagrams, while the terms “inside” and “outside” refer to the directions toward or away from the geometric center of a specific component, respectively.

[0016] To make the content of this invention easier to understand, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings.

[0017] As shown in Figure 1, a coaxial sequential pulse pulverized coal injection device with a narrow-throat Laval nozzle for blast furnaces adopts a double-layer coaxial structure. The inner layer is a pulverized coal conveying channel, and the outer layer is an oxygen channel. A narrow-throat Laval nozzle is installed at the end of the outer oxygen channel. The throat of the Laval nozzle has a straight section of 2-4.5 mm, which should be 2-4.5 mm away from the outer wall of the inner tube. That is, the diffuser section should also be 8-12 mm away from the outer wall of the inner tube. An external sequential pulse control module is provided to realize a coordinated injection mode of oxygen first pulse injection and pulverized coal delayed pulse injection.

[0018] Example 2: There is a 2-4.5mm straight section at the throat, which should be 2-4.5mm away from the outer wall of the inner tube. In other words, the diffuser section should also be 8-12mm away from the outer wall of the inner tube. This is suitable for blast furnaces with small air volume and high oxygen pressure.

[0019] Example 3: The diameter of the Laval nozzle throat is 4mm, the axial tube length difference is 12mm, and the rest of the structure is the same as in Example 1. It is suitable for large blast furnaces with large air volume and large coal injection volume.

[0020] First, the system starts oxygen pulse jet according to the preset program. High-pressure oxygen is delivered through the external oxygen channel, and after being pre-contracted and pressurized through the inlet contraction section, it enters the narrow throat section. After being throttled and focused by the 3mm narrow throat to form a critical airflow, it then passes through the outlet expansion section with a 9° expansion angle to uniformly increase speed, and finally forms a high-speed annular oxygen jet from the 6.5mm outlet, forming a high-speed oxygen coating layer around the device outlet.

[0021] Subsequently, the control system switched timings and initiated pulverized coal pulse injection, causing the pulverized coal to be evenly distributed through the central pulverized coal channel. The jet is ejected quickly because the outlet of the pulverized coal channel is 10mm smaller than the outlet of the oxygen channel. The central pulverized coal jet can be directly injected into the center of the high-speed annular oxygen layer without premature leakage or boundary diffusion.

[0022] By precisely controlling the pulse interval, injection duration, and injection pressure, the system achieves time-sharing and precise coordination between pulverized coal pulse injection and oxygen pulse injection. Each pulverized coal injection is matched with a stable high-speed oxygen jet, enabling instantaneous and efficient mixing and complete combustion of pulverized coal and oxygen. At the same time, the narrow-throat Laval nozzle continuously accelerates oxygen concentration, significantly improving oxygen penetration and mixing efficiency, thus solving problems such as turbulent airflow, uneven mixing, incomplete combustion, and carbon buildup and blockage in traditional pulverized coal injection devices.

[0023] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A coaxial Laval narrow-phase pulse pulverized coal injection device, characterized in that: The pulse pulverized coal injection device includes an inner pulverized coal channel (1) and an outer oxygen channel (2) arranged coaxially. The outer oxygen channel (2) is provided with a narrow throat Laval nozzle at its end. The throat diameter of the Laval nozzle is 2-4.5 mm. The axial tube length difference between the outlet end face of the inner pulverized coal channel (1) and the outlet end face of the outer oxygen channel (2) is 8-12 mm. The pulse pulverized coal injection device is connected to an external sequential pulse control system to realize pulsed time-sharing coordinated injection of pulverized coal and oxygen.

2. The coaxial Laval narrow-phase pulse pulverized coal injection device according to claim 1, characterized in that: The inner pulverized coal channel (1) is located in the center, and the outer oxygen channel (2) covers the outer side of the inner pulverized coal channel (1) to form a double-layer coaxial structure.

3. The coaxial Laval narrow-phase pulse pulverized coal injection device according to claim 1, characterized in that: The narrow-throat Laval nozzle is located only at the end of the external oxygen channel (2) and is used to concentrate and accelerate oxygen.

4. The coaxial Laval narrow-phase pulse pulverized coal injection device according to claim 1, characterized in that: The narrow-throat Laval nozzle includes an intake contraction section, a throat section, and an outlet expansion section connected in sequence. The intake contraction section is seamlessly connected to the external oxygen channel, and the inner wall of the throat section has a smooth arc transition structure.

5. A coaxial Laval narrow-phase pulse pulverized coal injection device according to claim 1, characterized in that: The expansion angle of the gas outlet expansion section is 6°-12°, and the outlet diameter of the gas outlet expansion section is 8-12mm, so that the high-pressure oxygen expands and increases at a uniform speed after being throttled through the throat.

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