A ductile cast iron pipe for ductile cast iron blast furnace

Abstract

The application discloses a cast iron blast furnace for nodular cast iron pipes, and relates to the technical field of cast iron, which comprises a blast furnace, a blower, a blast furnace, a feeding box and a material conveying belt, a screening module for grading and screening fuel particles is fixed in the feeding box; the screening module comprises screen plates one, two and three which are fixed in the feeding box from top to bottom; the screen plates one, two and three are placed obliquely and are respectively used for screening large-particle fuel, medium-particle fuel and small-particle fuel; a collecting frame is arranged at the bottom of the feeding box and is used for separately and quantitatively conveying the small-particle fuel by manual operation, so that the particle size distribution of the fuel is dynamically adjusted; the blast furnace can realize the technical effects of improving fuel combustion uniformity, improving combustion process stability, stabilizing fuel particle size distribution and being beneficial to the performance of the cast iron pipe after casting.

Description

A cast iron blast furnace for ductile iron pipes Technical Field

[0001] This invention relates to the field of cast iron technology, and in particular to a cast iron blast furnace for ductile iron pipes. Background Technology

[0002] The blast furnace is the core equipment in ironmaking. It mainly generates high temperatures through coke combustion to reduce iron ore into molten iron. Optimizing airflow distribution, heat exchange, and raw material reactions can improve the quality of the molten iron. The quality of combustion in the blast furnace directly affects the temperature distribution and composition of the molten iron. Incomplete combustion leads to temperature fluctuations, causing the content of key elements such as carbon, silicon, and manganese in the molten iron to deviate from the target range, thus affecting the spheroidization effect and mechanical properties of ductile iron.

[0003] For high-temperature casting of ductile iron pipes, Chinese invention patent CN113481339B discloses a cast iron blast furnace, including a blast furnace body, a blower on the surface of the blast furnace body, a blast furnace on one side of the blast furnace body, and a feeding box on the other side of the blast furnace body. The feeding box includes a box body with a discharge port at one end. A feeding device is provided between the blast furnace body and the feeding box. A suspension and circulation motion device is provided at the front end of the feeding device. The suspension and circulation motion device includes a fixed plate, a motor at one end of the fixed plate, and a conveyor belt connected to the rear end of the fixed plate. A pushing device is provided on the surface of the conveyor belt, and the pushing device includes a connecting plate. A screw is movably connected inside the connecting plate. This invention can prevent fuel from sticking to the surface of the feeding conveyor belt, reducing fuel waste, and can prevent round fuel lumps from sliding down, resulting in high feeding efficiency.

[0004] While the above-mentioned method improves casting efficiency to some extent when casting ductile iron pipes, in actual use, the preheating process of fuel with flue gas is problematic. The flue gas volume is unstable and its temperature is uncontrollable, resulting in uneven combustion. Furthermore, carbon dioxide in the flue gas adsorbs onto the fuel during preheating, affecting subsequent combustion. The uneven particle size distribution in the fuel leads to uncontrollable combustion, affecting the stability of the molten iron composition and potentially reducing the strength, toughness, corrosion resistance, and other properties of the cast ductile iron pipe. Summary of the Invention

[0005] This application provides a cast iron blast furnace for ductile iron pipes, which solves the technical problems of uneven fuel combustion, poor combustion process stability, unstable fuel particle size distribution and adverse effects on the performance of cast iron pipes after casting in the prior art. It achieves the technical effects of improved fuel combustion uniformity, improved combustion process stability, stable fuel particle size distribution and favorable performance of cast iron pipes after casting.

[0006] This application provides a cast iron blast furnace for ductile iron pipes, including a blast furnace, a blower, a blast furnace, a feed box and a conveyor belt, wherein a screening module for classifying and screening fuel particles is fixed inside the feed box;

[0007] The screening module includes screen plate one, screen plate two and screen plate three fixed inside the feed box from top to bottom; screen plate one, screen plate two and screen plate three are placed at an angle and are used to screen out large part fuel, medium part fuel and small part fuel respectively.

[0008] The bottom of the feed box is equipped with a collection frame for manually and quantitatively conveying small particulate fuel to dynamically adjust the particle size distribution of the fuel.

[0009] Furthermore, a conveying assembly for changing the fuel conveying trajectory is fixed between the blast furnace and the conveying belt; the conveying assembly includes a conveyor frame and a conveyor belt.

[0010] The conveyor frame is fixed to the right side of the conveyor belt; the conveyor belt is fixed to the conveyor frame by a drive assembly and is arranged at an angle to the left, so that the conveyor belt conveys to the lower right, for receiving and conveying large and medium-sized particulate fuel on the conveyor belt.

[0011] Furthermore, a sleeve is fixed at one end of the conveyor frame near and above the conveyor belt, and the sleeve is used to preheat large and medium particles by conveying flue gas.

[0012] Furthermore, the sleeve includes a large-diameter tube and a small-diameter tube;

[0013] The left end of the large-diameter pipe is fixed to the conveyor frame by a flange, and the other end is closed and slides with the small-diameter pipe. The large-diameter pipe is connected to the blast furnace exhaust duct through an external pipe and is used to transport flue gas to preheat the fuel. The small-diameter pipe is located inside the large-diameter pipe and extends to the outside of the large-diameter pipe. It is connected to an external air pump through a pipe and is used to transport air. Both the outer surfaces of the large-diameter pipe and the small-diameter pipe extending outside the large-diameter pipe are provided with through holes for discharging air and flue gas.

[0014] Furthermore, the coarse-diameter pipe and the fine-diameter pipe are rotatably connected by bearings. Both the coarse-diameter pipe and the fine-diameter pipe are promoted to rotate by the natural action of airflow and fuel transportation process, so as to achieve the best preheating and air replenishment effect.

[0015] Furthermore, the area of ​​the sleeve on the conveyor belt is divided into section A and section B. Section A is the preheating area and section B is the exhaust area. Section A is further divided into section A1 and section A2. Section A1 is the parting area and section A2 is the spreading area.

[0016] Furthermore, the width of the conveyor belt is 1.5 times the width of the material conveyor belt, and the conveyor belt is made of flexible material. When fuel accumulates in the middle of the conveyor belt, the middle of the conveyor belt is concave downward.

[0017] Furthermore, the conveyor frame is fixed with an adjustment unit for quantitatively controlling the particle size distribution of the fuel pile. The adjustment unit includes a parting plate, gears, belts, connecting rods, and a closed cover.

[0018] The parting plate is a triangular structure with its tip pointing downwards, fixed directly above the left end of the large-diameter pipe, used for parting the fuel; there are two sets of gears, each set including two gears arranged left and right, each set of gears is driven to rotate by an external motor; there are two belts, arranged front and back, corresponding one-to-one with each set of gears, and are sleeved on the outside of each corresponding set of gears through meshing transmission; there are multiple connecting rods, fixed between the two belts and evenly arranged along the circumference of the belts; there are multiple sealing covers, corresponding one-to-one with the connecting rods, respectively fixed on the corresponding connecting rods, used for quantitatively covering the parted fuel pile.

[0019] Furthermore, the area where the enclosure is located is section B. When the segmented fuel is transported to section B, the enclosure quantitatively covers it, and the narrow-diameter pipe begins to spray air. The small fuel particles in the middle of the two small fuel piles are blown apart by the air, so that the small fuel particles are mixed with the large and medium fuel particles.

[0020] Furthermore, the enclosure includes an outer shell, a metal sheet, and an airbag;

[0021] The metal sheet is fixed to the inner wall of the outer shell; the airbag is fixed between the metal sheet and the outer shell, and is used to exhaust the fuel pile by its own expansion, and to contract when air is injected through the narrow-diameter pipe to improve the mixing efficiency of small particles.

[0022] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0023] By introducing a grading and screening module and a DSDI dynamic control model, precise particle size classification is achieved through a three-stage sieve plate. A layered conveying strategy of "large particles sinking and small particles being covered separately" is adopted, so that the particle size distribution after fuel mixing approaches the ideal state (i.e., DSDI↑), significantly improving the surface area utilization rate. This effectively solves the technical problems of uneven fuel combustion, poor combustion process stability, unstable fuel particle size distribution, and adverse effects on the performance of cast iron pipes after casting in existing technologies. It achieves the technical effects of improved fuel combustion uniformity, improved combustion process stability, stable fuel particle size distribution, and benefits to the performance of cast iron pipes after casting. Attached Figure Description

[0024] Figure 1 is an overall structural diagram of a cast iron blast furnace for ductile iron pipes according to the present invention.

[0025] Figure 2 is a perspective sectional view of the charging box of a cast iron blast furnace for ductile iron pipes according to the present invention.

[0026] Figure 3 is a three-dimensional structural diagram of the conveyor belt and conveying components of a cast iron blast furnace for ductile iron pipes according to the present invention.

[0027] Figure 4 is a side perspective three-dimensional structural view of the conveyor belt and conveying assembly of a cast iron blast furnace for ductile iron pipes according to the present invention.

[0028] Figure 5 is a side perspective view of the conveying assembly of a cast iron blast furnace for ductile iron pipes according to the present invention.

[0029] Figure 6 is a right view of the casing of a cast iron blast furnace for ductile iron pipes according to the present invention.

[0030] Figure 7 is a three-dimensional structural diagram of the regulating unit of a cast iron blast furnace for ductile iron pipes according to the present invention.

[0031] Figure 8 is a front view of the conveying assembly and regulating unit of a cast iron blast furnace for ductile iron pipes according to the present invention.

[0032] Figure 9 is a schematic diagram of the state of jet mixing of large, medium and small particulate fuels in the closed hood of a cast iron blast furnace for ductile iron pipes according to the present invention.

[0033] In the diagram: 100, blast furnace; 110, blower; 120, blast furnace; 130, feed box; 132, sieve plate one; 133, sieve plate two; 134, sieve plate three; 135, collection frame; 140, conveyor belt; 150, conveyor assembly; 151, conveyor frame; 152, conveyor belt; 160, sleeve; 161, large diameter pipe; 162, small diameter pipe; 200, adjusting unit; 210, parting plate; 220, gear; 230, belt; 240, connecting rod; 250, enclosed cover; 251, outer shell; 252, metal sheet; 253, air bag. Detailed Implementation

[0034] To facilitate understanding of the present invention, a more complete description of this application will be given below with reference to the accompanying drawings, which illustrate preferred embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough and complete understanding of the disclosure of the present invention.

[0035] It should be noted that the terms "vertical," "horizontal," "up," "down," "left," "right," and similar expressions used in this article are for illustrative purposes only and do not represent the only possible implementation.

[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 invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] Please refer to Figure 1, which is a schematic diagram of the overall structure of a cast iron blast furnace for ductile iron pipes according to the present invention. The cast iron blast furnace for ductile iron pipes in this application introduces a grading and screening module and a DSDI dynamic control model. It achieves precise particle size classification through a three-stage sieve plate and adopts a layered conveying strategy of "large particles sinking and small particles covering separately" so that the particle size distribution after fuel mixing is close to the ideal state (i.e., DSDI↑), which significantly improves the surface area utilization rate, weakens the oxygen blocking effect of large particles, and improves combustion efficiency. It achieves the technical effects of improved fuel combustion uniformity, improved combustion process stability, stable fuel particle size distribution, and is beneficial to the performance of cast iron pipes after casting.

[0038] Example 1: As shown in Figures 1 and 2, this application discloses a cast iron blast furnace for ductile iron pipes, including a blast furnace 100, a blower 110, a blast furnace 120, a feed box 130, and a conveyor belt 140. The feed box 130 is equipped with a screening module for classifying and screening fuel particles.

[0039] The screening module includes a first screen plate 132, a second screen plate 133, and a third screen plate 134, which are fixed inside the feed box 130 from top to bottom. The first screen plate 132, the second screen plate 133, and the third screen plate 134 are placed at an angle and are used to screen out large particulate fuel, medium particulate fuel, and small particulate fuel, respectively.

[0040] The bottom of the feed box 130 is provided with a collection frame 135, which is used to manually and quantitatively convey small particulate fuel to dynamically adjust the particle size distribution of the fuel.

[0041] The conveyor belt 140 is used to transport large and medium-sized particulate fuel and is driven by an electric motor, which is existing technology and will not be described in detail here.

[0042] In the casting of ductile iron pipes, combustion quality directly affects the temperature distribution and composition of molten iron in the furnace. Incomplete combustion leads to temperature fluctuations, causing the content of key elements such as carbon, silicon, and manganese in the molten iron to deviate from the target range, thereby affecting the spheroidization effect and mechanical properties of ductile iron. Good combustion conditions can promote desulfurization reaction and avoid sulfur interfering with spheroidization reaction. The uniformity and stability of fuel particle size distribution are the core elements for evaluating the quality of combustion. A uniform and stable particle size distribution can ensure that the fuel and oxidant are in full contact, improve combustion efficiency, and guarantee the performance of ductile iron pipes after casting.

[0043] The Dynamics of Fuel Particle Size Distribution (DSDI) is used to quantify the stratification and mixing uniformity of fuel particles during transportation. Its definition is as follows:

[0044]

[0045] in, : The total surface area of ​​fuel particles under ideal conditions (based on optimal particle size distribution);

[0046] The total surface area actually measured;

[0047] Standard deviation of ideal particle size distribution (preset value);

[0048] Standard deviation of actual particle size distribution;

[0049] , Weighting coefficients (usually determined experimentally) ).

[0050] Its physical meaning is: DSDI↑, which means that the actual particle size distribution approaches the ideal state.

[0051] Finally, fuel combustion efficiency ( Relationship between fuel particle size distribution dynamic index (DSDI) and fuel particle size distribution dynamic index (DSDI):

[0052]

[0053] Fuel preheating temperature (related to orifice jet temperature);

[0054] Combustion reaction kinetic constant (calibrated by thermogravimetric analysis).

[0055] Therefore, by artificially interfering with the mixing uniformity of large, medium and small particles to make it tend towards an ideal state, the ratio of the above parameters can be maximized (approaching the integer 1), and the particle size distribution dynamic index can be stabilized (i.e., tending to the maximum value). When the DSDI value stabilizes (i.e. the value increases), the combustion efficiency is also improved accordingly while other parameters remain unchanged, thereby improving the combustion efficiency and the casting quality of ductile iron pipes.

[0056] This application introduces a grading and screening module and a DSDI dynamic control model to achieve precise particle size classification through a three-stage sieve plate. It adopts a layered conveying strategy of "large particles sinking and small particles covering the back". Through the systematic control of screening-quantification-layering, the particle size distribution after fuel mixing approaches the ideal state (i.e., DSDI↑), which significantly improves the surface area utilization rate and weakens the oxygen blocking effect of large particles, thereby improving combustion efficiency.

[0057] In actual operation, the steps of this embodiment are as follows: First, fuel is fed into the feed box 130 through the feed inlet. Fuel of different particle sizes is sequentially screened through sieve plate 132, sieve plate 133, and sieve plate 134 to be divided into large particle fuel, medium particle fuel, and small particle fuel. Large and medium particle fuels fall onto the conveyor belt 140 and are conveyed by the conveyor belt 140. Small particle fuels are collected separately through the collection frame 135. Next, the small particle fuels are manually quantified and then covered with the large and medium particle fuels before being conveyed into the blast furnace 100 for combustion. Finally, the raw materials are melted into molten iron through combustion in the blast furnace 100, and then subjected to spheroidization, centrifugal casting, heat treatment, and finishing processes in sequence.

[0058] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0059] By setting up three sieve plates—132, 133, and 134—that are tilted and fixed from top to bottom, fuel can be precisely graded and screened into large, medium, and small particles. This grading and screening helps optimize the particle size distribution after fuel mixing, making the DSDI (Displacement Difference in Density Index) distribution more uniform and closer to the ideal state. The screening module adjusts the order in which fuel enters the conveyor belt 140 (large particles sink first, small particles cover the surface), and based on the DSDI value, dynamically optimizes the particle size distribution by controlling the amount of small particles (DSDI↑), reducing the amount of large particles. The oxygen-blocking effect allows for more precise adjustment of the particle size distribution after fuel mixing, thereby maintaining a more stable combustion state during combustion. This helps reduce combustion fluctuations caused by unstable particle size distribution, improving the production efficiency and product quality of blast furnace 100. It solves the technical problems of uneven fuel combustion, poor combustion process stability, unstable fuel particle size distribution, and adverse effects on the performance of cast iron pipes after casting in existing technologies. It achieves the technical effects of improved fuel combustion uniformity, improved combustion process stability, stable fuel particle size distribution, and improved performance of cast iron pipes after casting.

[0060] Example 2: To improve the preheating effect of flue gas and reduce the occurrence of incomplete combustion caused by carbon dioxide adsorption on fuel, this application proposes the following technical solution to address the above-mentioned technical problems:

[0061] As shown in Figures 1 to 6, a conveying assembly 150 for changing the fuel conveying trajectory is fixed between the blast furnace 100 and the conveying belt 140. The conveying assembly 150 includes a conveying frame 151 and a conveying belt 152.

[0062] The conveyor frame 151 is fixed to the right side of the conveyor belt 140; the conveyor belt 152 is fixed to the conveyor frame 151 by a drive assembly and is arranged at an angle to the left, so that the conveyor belt 152 conveys to the lower right, for receiving and conveying large and medium particle fuel on the conveyor belt 140.

[0063] The conveyor frame 151 is fixed with a sleeve 160 at one end near the conveyor belt 140 and above the conveyor belt 152. The sleeve 160 is used to preheat large and medium particles by conveying flue gas.

[0064] The sleeve 160 includes a large-diameter tube 161 and a small-diameter tube 162;

[0065] The left end of the coarse-diameter pipe 161 is fixed to the conveyor frame 151 by a flange, and the other end is closed and slides with the fine-diameter pipe 162. The coarse-diameter pipe 161 is connected to the exhaust duct of the blast furnace 100 through an external pipe and is used to transport flue gas to preheat the fuel. The fine-diameter pipe 162 is located inside the coarse-diameter pipe 161 and extends to the outside of the coarse-diameter pipe 161. It is connected to an external air pump through a pipe and is used to transport air.

[0066] Both the outer surfaces of the coarse-diameter pipe 161 and the fine-diameter pipe 162 extending outside the coarse-diameter pipe 161 are provided with through holes for discharging air and flue gas.

[0067] The coarse-diameter pipe 161 and the fine-diameter pipe 162 are rotatably connected by bearings. Both the coarse-diameter pipe 161 and the fine-diameter pipe 162 are rotated by the natural action of airflow and fuel transportation to achieve the best preheating and air replenishment effect.

[0068] The area of ​​the sleeve 160 on the conveyor belt 152 is divided into section A and section B. Section A is the preheating area and section B is the exhaust area. Section A is further divided into section A1 and section A2. Section A1 is the parting area and section A2 is the spreading area.

[0069] The drive assembly is used to drive the conveyor belt 152 to rotate, preferably a servo motor drive, which is existing technology and will not be described in detail here.

[0070] The height of the conveyor belt 140 is higher than the highest point of the conveyor belt 152. By increasing the conveying height of the conveyor belt 140 and designing the conveyor belt 152 to convey downwards, the fuel conveying path is optimized by conveying downwards to the blast furnace 100. This effectively avoids the fuel from sliding down into the feed box 130 due to gravity during the upward conveying process, which not only reduces fuel waste but also ensures the continuity and stability of the conveying process.

[0071] This application, by setting a sleeve 160 in the middle of the conveyor belt 152, not only enables preheating of the mixed fuel of large and medium particles through the coarse-diameter pipe 161, increasing the initial temperature of the fuel and helping to accelerate the combustion process, but also enables the replacement of carbon dioxide in the fuel pile and the supply of oxygen to the interparticle spaces through the fine-diameter pipe 162.

[0072] After the fuel moves to the B-section exhaust area, the air sprayed from the narrow-diameter pipe 162 can replace the carbon dioxide adsorbed on the surface of the fuel, providing sufficient oxygen for the complete combustion of the fuel. This not only improves the combustion efficiency of the fuel, but also reduces the incomplete combustion caused by carbon dioxide adsorption. Through preheating treatment and oxygen supplementation, the fuel has reached a high temperature and sufficient oxygen environment before entering the blast furnace 100, which helps the fuel to burn completely in the blast furnace 100.

[0073] Example 3: To further precisely control the particle size distribution of each fuel pile, and to ensure more thorough mixing of small fuel particles with large and medium-sized fuel particles, this application proposes the following technical solution to address the aforementioned technical problems:

[0074] As shown in Figures 3 to 9, the width of the conveyor belt 152 is 1.5 times the width of the conveyor belt 140. The conveyor belt 152 is made of flexible material. When fuel accumulates in the middle of the conveyor belt 152, the middle of the conveyor belt 152 is concave downward.

[0075] The conveyor frame 151 is fixed with an adjustment unit 200 for quantitatively controlling the particle size distribution of the fuel pile. The adjustment unit 200 includes a parting plate 210, a gear 220, a belt 230, a connecting rod 240, and a closed cover 250.

[0076] The parting plate 210 is a triangular structure with its tip pointing downwards, fixed directly above the left end of the coarse-diameter pipe 161, and is used to part the fuel. Two sets of gears 220 are provided, each set including two gears arranged left and right, each set driven by an external motor. Two belts 230 are provided, arranged front and back, corresponding one-to-one with each set of gears 220, and are fitted onto the outside of each corresponding set of gears 220 through meshing transmission. Multiple connecting rods 240 are provided, fixed between the two belts 230 and evenly arranged circumferentially along the belts 230. Multiple sealing covers 250 are provided, corresponding one-to-one with the connecting rods 240, and fixed to the corresponding connecting rods 240, used to quantitatively cover the parted fuel stack.

[0077] The area where the enclosure 250 is located is section B. When the fuel after being sorted is transported to section B, the enclosure 250 covers it quantitatively, and the narrow-diameter pipe 162 starts to spray air. The small fuel particles in the middle of the two small fuel piles are blown apart by the air, so that the small fuel particles are mixed with the large and medium fuel particles.

[0078] The transmission direction of the belt 230 is opposite to that of the conveyor belt 152. The conveyor belt 152 is 1.5 times wider than the conveyor belt 140 and is made of flexible material, which allows the fuel pile to sink downward in the middle of the conveyor belt 152, which is beneficial for fuel separation and mixing. At the same time, the design of the circulating cover 250 and its synchronous movement with the conveyor belt 152 can achieve quantitative covering and shaping of the fuel pile, improving operational efficiency and accuracy.

[0079] This application uses a parting plate 210 to first divide the mixed fuel of large and medium particles into two smaller piles. Then, when the fuel in the two smaller piles moves to the A2 area, the amount of small particles between the fuel in the two smaller piles after parting is manually and stably controlled in the A2 section (the amount added is determined by human intervention). With the quantitative coverage of the enclosure 250, the mixing ratio of large, medium and small particles in each fuel pile can be adjusted more precisely.

[0080] When the fuel pile moves to the B-section exhaust mixing area, the fuel pile is quantitatively covered by the sealing hood 250, and the air sprayed through the narrow diameter pipe 162 blows and diffuses the small fuel particles into the gaps between the large and medium-sized fuel particles, achieving relative uniformity of mixing among the three, further optimizing the particle size distribution, reducing the stratification effect, and thus maintaining a more stable combustion state during the combustion process in blast furnace 100. By controlling the fuel mixing ratio and particle size distribution more precisely, fuel waste and incomplete combustion caused by uneven particle size distribution are reduced, ensuring the quality of the ductile iron pipe after casting.

[0081] Example 4: To further improve the mixing uniformity of small-particle fuel in large and medium-particle fuel reactors, and to improve the mixing efficiency of large, medium, and small particles, this application proposes the following technical solution to address the above-mentioned technical problems:

[0082] As shown in Figures 8 and 9, the enclosure 250 includes an outer shell 251, a metal sheet 252, and an airbag 253;

[0083] The metal sheet 252 is fixed to the inner wall of the outer shell 251; the airbag 253 is fixed between the metal sheet 252 and the outer shell 251, and is used to exhaust the fuel pile by its own expansion, and to contract when air is sprayed from the narrow diameter pipe 162 to improve the mixing efficiency of small particles.

[0084] The metal sheet 252 is a thin metal sheet with good toughness and heat insulation properties. It is preferably an aluminum-based composite material. The expansion of the airbag 253 can compress the fuel pile and expel as much carbon dioxide and air as possible from the quantitative fuel pile. When air is introduced, the airbag 253 contracts, so that when the air is ejected, it can blow away small fuel particles and blow them into the gaps between large and medium-sized fuel particles, making them more uniformly mixed.

[0085] This application utilizes the expansion of the airbag 253 to compress the two small fuel piles. This physical action helps to expel as much carbon dioxide as possible from the fuel piles. When the airbag 253 contracts, air is ejected from the through-hole of the narrow-diameter tube 162, using the airflow energy to disperse the small fuel particles and blow them into the gaps between the large and medium-sized fuel particles. This dynamic mixing method is more effective than static mixing and can significantly improve the mixing uniformity of small fuel particles in the large and medium-sized fuel piles. The uniformly mixed fuel piles have better permeability, which helps to distribute oxygen evenly in the fuel piles, reducing local incomplete combustion caused by uneven oxygen distribution and improving overall combustion efficiency. The uniformly mixed fuel piles can also reduce temperature gradients and hot spots during combustion, making the combustion process more stable and controllable. Finally, operators can adjust the working state of the airbag 253 according to actual needs to adapt to the mixing requirements of different fuel types and combustion conditions.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cast iron blast furnace for ductile iron pipes, comprising a blast furnace (100), a blower (110), a blast furnace (120), a charging box (130), and a conveyor belt (140), characterized in that, The feed box (130) is equipped with a screening module for classifying and screening fuel particles. The screening module includes a first screen plate (132), a second screen plate (133), and a third screen plate (134) fixed inside the feed box (130) from top to bottom. The first screen plate (132), the second screen plate (133), and the third screen plate (134) are placed at an angle and are used to screen out large-particle fuel, medium-particle fuel, and small-particle fuel, respectively. A collection frame (135) is provided at the bottom of the feed box (130) for manually and quantitatively conveying small-particle fuel to dynamically adjust the particle size distribution of the fuel. A conveying assembly (150) for changing the fuel conveying trajectory is fixed between the blast furnace (100) and the conveying belt (140). The conveying assembly (150) includes a conveying frame (151) and a conveying belt (152). A sleeve (160) is fixed to one end of the conveying frame (151) near the conveying belt (140) and above the conveying belt (152). The sleeve (160) is used to preheat large and medium-sized particles by conveying flue gas. The sleeve (160) includes a large-diameter pipe (161) and a small-diameter pipe (162). The area of ​​the sleeve (160) on the conveying belt (152) The system is divided into two sections: Section A is the preheating area, and Section B is the exhaust area. Section A is further divided into Section A1 and Section A2. Section A1 is the parting area, and Section A2 is the spreading area. A regulating unit (200) for quantitatively controlling the particle size distribution of the fuel pile is fixed on the conveyor frame (151). The regulating unit (200) includes a parting plate (210), a gear (220), a belt (230), a connecting rod (240), and a sealing cover (250). The area where the sealing cover (250) is located is Section B. When the parted fuel is conveyed to Section B, the sealing cover... The enclosure (250) quantitatively covers the fuel pile, and the narrow-diameter pipe (162) begins to spray air. The small fuel particles in the middle of the two small fuel piles are blown apart by the air, so that the small fuel particles are mixed with the large and medium fuel particles. The enclosure (250) includes an outer shell (251), a metal sheet (252) and an airbag (253). The metal sheet (252) is fixed to the inner wall of the outer shell (251). The airbag (253) is fixed between the metal sheet (252) and the outer shell (251) and is used to exhaust the fuel pile by its own expansion and to contract when air is sprayed from the narrow-diameter pipe (162) to improve the mixing efficiency of small particles.

2. The cast iron blast furnace for ductile iron pipes as described in claim 1, characterized in that, The conveyor frame (151) is fixed to the right side of the conveyor belt (140); the conveyor belt (152) is fixed to the conveyor frame (151) by the drive assembly and is arranged to the left, so that the conveyor belt (152) conveys to the lower right, for receiving and conveying large and medium particle fuel on the conveyor belt (140).

3. The cast iron blast furnace for ductile iron pipes as described in claim 2, characterized in that, The left end of the large-diameter pipe (161) is fixed to the conveyor frame (151) by a flange, and the other end is closed and slides with the small-diameter pipe (162). The large-diameter pipe (161) is connected to the exhaust duct of the blast furnace (100) through an external pipe and is used to transport flue gas to preheat the fuel. The small-diameter pipe (162) is located inside the large-diameter pipe (161) and extends to the outside of the large-diameter pipe (161). It is connected to an external air pump through a pipe and is used to transport air. The outer surfaces of the large-diameter pipe (161) and the small-diameter pipe (162) extending outside the large-diameter pipe (161) are both provided with through holes for discharging air and flue gas.

4. The cast iron blast furnace for ductile iron pipes as described in claim 3, characterized in that, The coarse-diameter pipe (161) and the fine-diameter pipe (162) are rotatably connected by bearings. Both the coarse-diameter pipe (161) and the fine-diameter pipe (162) are rotated by the natural action of airflow and fuel transportation to achieve the best preheating and air replenishment effect.

5. A cast iron blast furnace for ductile iron pipes as described in claim 2, characterized in that, The width of the conveyor belt (152) is 1.5 times the width of the conveyor belt (140). The conveyor belt (152) is made of flexible material. When fuel accumulates in the middle of the conveyor belt (152), the middle of the conveyor belt (152) is concave downward.

6. The cast iron blast furnace for ductile iron pipes as described in claim 1, characterized in that, The parting plate (210) is a triangular structure with its tip pointing downwards. It is fixed directly above the left end of the coarse-diameter pipe (161) and is used to part the fuel. There are two sets of gears (220). Each set of gears (220) includes two gears (220) arranged on the left and right sides. Each set of gears (220) is driven to rotate by an external motor. There are two belts (230) arranged in front and behind each other. They correspond one-to-one with each set of gears (220) and are sleeved on the outside of each set of gears (220) through meshing transmission. There are multiple connecting rods (240) that are fixed between the two belts (230) and evenly arranged around the belts (230). There are multiple sealing covers (250) that correspond one-to-one with each connecting rod (240) and are fixed on the corresponding connecting rods (240) respectively. They are used to quantitatively cover the parted fuel pile.

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