A multi-stage volute feed cyclonic flash reactor and method for cracking natural gas to carbon black

Abstract

The application discloses a kind of multistage volute feed cyclone pyrolyzer and natural gas pyrolysis carbon black method, the core of the pyrolyzer is at least three layers of coaxial concentric nested volute assembly, outer layer is air volute, radial inner layer is fuel gas volute, the rest inner layer is raw material gas volute, all volute same direction is same;Air volute inner cylinder is provided with rectangular guide opening;Furnace is divided into combustion zone, pyrolysis zone, heat supplement zone along axial direction;High-temperature combustion residue gas generated by combustion is wrapped with raw material gas by same direction spiral flow, realizes oxygen-free laminar flow pyrolysis by heating layer by layer from outside to inside, heat supplement zone is provided with supplementary air inlet, utilize the characteristics that hydrogen combustion speed is far faster than that of methane, preferentially combustion pyrolysis by-product hydrogen in situ heat supplement.The application can fundamentally solve the principle contradiction of combustion and pyrolysis, natural gas total consumption can be reduced to 4000Nm³ / ton carbon black below, 33% lower than traditional process, carbon black yield can be up to 79%, product quality is stable, with significant energy-saving effect and industrial application value.

Description

Technical Field

[0001] This invention relates to the field of carbon black production equipment and process technology, and more specifically, to a multi-stage volute-feed cyclone pyrolyzer for preparing semi-reinforcing carbon black by thermal cracking of natural gas, and a method for producing carbon black by natural gas cracking using the pyrolyzer. Background Technology

[0002] Carbon black is an indispensable reinforcing filler in the rubber industry and is also widely used in plastics, inks, coatings and other fields. Semi-reinforcing carbon black has the characteristics of large particle size, low structure, good elasticity and low heat generation. It is mainly used in rubber products such as tire sidewalls, hoses, belts and seals. The mainstream industrial production process for semi-reinforcing carbon black is natural gas pyrolysis.

[0003] The core principle of preparing semi-reinforcing carbon black from natural gas through pyrolysis is as follows: methane undergoes a directional pyrolysis reaction (CH4→C+2H2) at a high temperature of 1300-1400℃ in an oxygen-free environment, producing carbon black and hydrogen. In actual production, a portion of the natural gas needs to be burned as fuel to provide high-temperature heat for the pyrolysis reaction, while the other portion is used as a raw material for pyrolysis.

[0004] Currently, conventional processes and equipment in the industry suffer from long-standing technical pain points that cannot be resolved. These include: existing pyrolyzers generally adopt a single-feed structure, where the feedstock natural gas is not separated into fuel gas before entering the furnace. The feedstock natural gas and fuel gas are mixed and injected into the furnace through the same channel, meaning that part of the feedstock natural gas is used as fuel gas, creating a coupled operating condition of "combustion and pyrolysis simultaneously." Actual production data shows that the total natural gas consumption for producing 1.5 tons of reinforcing carbon black using traditional processes is as high as 6000 standard cubic meters (Nm³).

[0005] Theoretical thermodynamic calculations show that producing 1 ton of carbon black requires only about 1870 Nm³ of natural gas as feedstock (based on the stoichiometric ratio of CH4 cracking to C). Considering the endothermic reaction and the heat required for material heating, under ideal conditions with no additional heat loss, the theoretical minimum total natural gas consumption (feedstock gas + fuel gas) for producing 1 ton of carbon black is only 3300-3400 Nm³. It is evident that the current process consumes far more natural gas than the theoretical limit, indicating significant potential for energy savings. However, this is accompanied by problems such as low carbon black yield and unstable product quality.

[0006] To address the aforementioned issues, the industry has undertaken various improvement attempts: some technical routes employ regenerative thermal pyrolysis, recovering the combustion heat of deposits through alternating heating and pyrolysis cycles; however, this process is a periodic intermittent operation with complex equipment structures, making it unsuitable for large-scale continuous production; some technical routes utilize a recirculated gas reuse process, improving the combustion rate by recycling a portion of the gas-solid mixture and premixing it with the raw materials; however, spatial separation between the combustion and pyrolysis zones is still not achieved, and the core contradiction between combustion and pyrolysis remains; some technologies employ a dual-combustion chamber structure to provide a stable heat source, but the raw material gas is still directly mixed with the high-temperature flue gas, inevitably resulting in oxidation combustion and low raw material utilization; other technologies attempt to purify the pyrolysis byproduct hydrogen for reuse as fuel, but this requires additional purification and pressurization equipment, leading to high investment costs and the inability to replenish heat in situ within the pyrolysis furnace, resulting in significant heat loss.

[0007] In summary, none of the existing technological improvement approaches have fundamentally solved the long-standing technical problems in the industry:

[0008] The fundamental contradiction between combustion and pyrolysis is irreconcilable: combustion requires thorough mixing of fuel and air for complete combustion, while pyrolysis requires the feed gas to be strictly isolated from air and maintain a stable laminar flow. The coupling of these two conditions in the same area inevitably leads to mutual interference, resulting in ineffective oxidation of the feed gas. Furthermore, there is significant ineffective consumption of feed gas: the unavoidable mixing of feed gas and air causes a large amount of feed gas to be oxidized and burned before pyrolysis, resulting in carbon black yields generally below 65% and persistently high natural gas energy consumption. Finally, the pyrolysis reaction has poor controllability: the mixing method of high-temperature residual gas and feed gas is uncontrollable, leading to uneven temperature distribution within the furnace and uneven pyrolysis reaction. This results in a wide carbon black particle size distribution, poor structural stability, and a low product qualification rate, failing to meet the application requirements of high-end rubber products.

[0009] Low heat utilization rate: Hydrogen, a byproduct of pyrolysis, has a high calorific value (10.8 MJ / Nm³), but existing technologies cannot economically and safely recover and utilize it in situ. A large amount of chemical heat is discharged with the exhaust gas, further aggravating energy waste. Summary of the Invention

[0010] The purpose of this invention is to overcome the aforementioned deficiencies of the prior art and provide a multi-stage volute-feed cyclone pyrolyzer and a corresponding pyrolysis method for producing carbon black. Through a multi-layered, coaxial, concentrically nested volute assembly, it achieves staged independent feeding of fuel gas and feed gas, and complete spatial separation of the combustion zone and pyrolysis zone, fundamentally resolving the inherent contradiction between combustion and pyrolysis principles. Simultaneously, it forms a stable cyclone through co-rotating guide vanes, eliminating turbulence interference. Through a selective post-heating structure, it utilizes the order-of-magnitude difference in combustion rates between hydrogen and methane to preferentially burn pyrolysis byproduct hydrogen to supplement pyrolysis heat in situ, achieving efficient cascaded energy utilization. Ultimately, it significantly reduces natural gas consumption and improves carbon black yield and product quality.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] This invention provides a multi-stage volute-feed cyclone pyrolyzer, comprising a cylindrical furnace body and a volute assembly. The furnace body has a combustion zone and a pyrolysis reaction zone. The volute assembly includes an air volute, a fuel gas volute, and at least one feed gas volute, all concentrically nested from the outside in, with all volutes having the same cyclone direction. The air volute, fuel gas volute, and feed gas volute each have a medium inlet port communicating with their flow channels. The air volute is fixedly connected to the feed end of the furnace body. One end of the air volute and the fuel gas volute are open and extend to the combustion zone, and one end of the feed gas volute is open and extends to the pyrolysis reaction zone. Multiple flow guide openings are evenly distributed on the circumference of the inner cylinder of the air volute, and the air volute and the fuel gas volute are connected through the flow guide openings.

[0013] A further technical solution is that the flow guiding direction of each layer of the volute assembly is either right-handed or left-handed, and the swirling angle between adjacent volutes is the quotient obtained by dividing the number of stages by 360°. For example, if the number of volute stages is 4, then the swirling angle between adjacent volutes is 90°.

[0014] Optionally, the raw material gas volute includes a second raw material gas volute and a first raw material gas volute nested within the second raw material gas volute; the pyrolysis reaction zone of the furnace body includes a first gradient pyrolysis reaction zone near the combustion zone and a second gradient pyrolysis reaction zone behind the first gradient pyrolysis reaction zone; the end of the second raw material gas volute extends to the first gradient pyrolysis reaction zone, and the end of the first raw material gas volute extends to the second gradient pyrolysis reaction zone.

[0015] A further technical solution involves a selective heating zone within the furnace body. This zone is located behind the second gradient pyrolysis reaction zone and includes at least two supplementary air inlets. These inlets are evenly distributed around the circumference of the furnace body and feature a tangentially offset design. The air inlet direction aligns with the rotation direction of the volute assembly, and the inlet end forms a 30°-60° angle with the swirling pyrolysis channel at the center of the furnace. More specifically, the inlet end of the supplementary air inlet extends to the outer wall of the furnace body, while the outlet end extends into the interior of the furnace body corresponding to the selective heating zone.

[0016] An ignition gun assembly is embedded in the central axial position of the first raw material gas volute. The ignition gun assembly is sealed to the first raw material gas volute, and the front end of the ignition gun body extends into the combustion zone. More specifically, the ignition gun assembly includes an ignition gun body and a high-temperature resistant sealing flange. The front end of the ignition gun body extends into the furnace body, and the rear end is sealed to the end cap of the first raw material gas volute via the high-temperature resistant sealing flange. The ignition gun assembly is only used for ignition and furnace preheating during the equipment start-up phase to raise the furnace temperature to the rated reaction temperature. During normal production, it is closed and sealed, without interfering with the gas flow and pyrolysis reaction within the furnace.

[0017] The combustion zone is the 0-600mm section of the feed end of the furnace body. The first gradient pyrolysis reaction zone and the second gradient pyrolysis reaction zone are located 600-1900mm downstream of the feed end of the furnace body. The selective reheating zone is located 1500-2500mm downstream of the feed end of the furnace body.

[0018] Optionally, the number of flow guiding openings is four, which are evenly distributed along the circumference of the inner cylinder of the air volute and are equally spaced in the axial direction. The aspect ratio of a single rectangular flow guiding opening is not less than 2:1, and the total area of ​​all flow guiding openings accounts for 8%-12% of the cross-sectional area of ​​the inner cylinder of the air volute.

[0019] Optionally, the air volute, fuel gas volute, and feedstock gas volute are each provided with an annular baffle at their ends, and each volute extends to its corresponding zone through the annular baffle. A third annular baffle is connected to the outer wall of the fuel gas volute, and the end of the third annular baffle extends to the combustion zone. A first annular baffle is connected to the outer wall of the first feedstock gas volute, and a second annular baffle is connected to the outer wall of the second feedstock gas volute; wherein the end of the second annular baffle extends to the first gradient pyrolysis reaction zone, and the end of the first annular baffle extends to the second gradient pyrolysis reaction zone.

[0020] The furnace body is equipped with a cooling device at the discharge end for rapid cooling of the pyrolysis products; preferably, the inner wall of the furnace body is lined with a refractory layer, and the overall material of the volute assembly is high-temperature resistant stainless steel or high-nickel-based steel.

[0021] This invention also provides a method for producing carbon black from natural gas through cracking, using the aforementioned multi-stage volute feed cyclone cracker, comprising the following steps:

[0022] (1) Start the furnace: Ignite the furnace by igniting the ignition gun assembly, introduce combustion air into the air volute, and introduce fuel natural gas into the fuel gas volute. After the air and fuel natural gas are premixed, they burn to form a stable flame. Bake the furnace to the rated reaction temperature of 1200-1500℃ according to the heating curve given by the process.

[0023] (2) Staged feeding and complete combustion: Fuel natural gas is continuously fed into the fuel gas volute, and combustion air is continuously fed into the air volute; 25%-35% of the combustion air enters the fuel gas volute through the guide opening and is premixed with the fuel natural gas to form premixed gas. The remaining combustion air enters the combustion zone through the air volute channel and is mixed with the premixed gas for complete combustion, generating high-temperature waste gas at 1750-1800℃.

[0024] (3) Gradient laminar flow pyrolysis: The high-temperature residual gas enters the gradient pyrolysis reaction zone from the combustion zone in a swirling state in the same direction as the raw material natural gas. It surrounds the raw material natural gas ejected from the raw material gas volute and heats the raw material natural gas layer by layer from the outside to the inside through radiation and convection heat exchange, so that the raw material natural gas undergoes a progressive thermal pyrolysis reaction in an oxygen-free laminar flow state, generating carbon black and hydrogen-containing pyrolysis gaseous products.

[0025] (4) Selective supplementary heating: After the cracked gaseous products enter the selective supplementary heating zone with the material flow, supplementary air is introduced through the supplementary air inlet. Taking advantage of the characteristic that the flame propagation speed of hydrogen is much faster than that of methane, the supplementary air preferentially undergoes partial combustion with the hydrogen in the cracked gaseous products, and the heat released provides a supplementary heat source for the cracking of the remaining uncracked natural gas.

[0026] (5) Product collection: The product after the pyrolysis reaction is completed is rapidly cooled to terminate the reaction and separated into gas and solid to obtain carbon black product.

[0027] A further technical solution is:

[0028] In step (2), the total amount of combustion air introduced is 1.0-1.05 times the theoretical amount of air required for the complete combustion of fuel natural gas; the amount of fuel natural gas introduced is 1400-2200 Nm³ / ton of carbon black;

[0029] In step (3), the raw natural gas is divided into two streams and introduced into the two layers of raw gas volutes on the radial inner side. The volume ratio of the two streams of raw gas is (3.5-4.5):(5.5-6.5), preferably 4:6. The total amount of raw natural gas introduced is 2150-3000 Nm³ / ton of carbon black.

[0030] In step (4), the amount of supplementary air introduced is 30%-40% of the theoretical stoichiometric amount of air required for the complete combustion of the pyrolysis gaseous products;

[0031] In step (5), the product is rapidly cooled to 700-800℃ to terminate the reaction.

[0032] In this invention, "raw material natural gas" and "fuel natural gas" refer to the same type of natural gas, differing only in their applications. Raw material natural gas can be simply referred to as raw material gas, and fuel natural gas can be simply referred to as fuel gas.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] 1. Completely resolves the fundamental contradiction in combustion and cracking operations: Through the radial partitioned flow channel and axial functional partition design of the multi-layer concentric volute, complete spatial separation of combustion heating and feedstock cracking is achieved for the first time. That is, the fuel gas is precisely air-distributed and fully combusted in the combustion zone, while the feedstock gas is isolated from air and undergoes laminar flow cracking in the cracking zone. This fundamentally eliminates the core contradiction of "combustion requires sufficient oxygen mixing and cracking requires strict oxygen isolation", and completely avoids the ineffective combustion loss of feedstock natural gas.

[0035] 2. Significantly reduce the overall energy consumption of natural gas: Through a triple heat efficiency utilization mechanism of gradient heat exchange preheating, co-current swirl enhanced heat exchange, and in-situ selective reheating of cracking byproduct hydrogen, the overall energy consumption of natural gas can be reduced from 6000 Nm³ / ton of carbon black in the traditional process to a minimum of about 4000 Nm³ / ton of carbon black, which is about 33% lower than the traditional process and infinitely close to the theoretical limit of 3400 Nm³, thus significantly reducing the production cost of semi-reinforcing carbon black.

[0036] 3. Significantly Improved Carbon Black Yield and Product Quality: The gradual gradient heating mode from the outside to the inside can stably control the pyrolysis reaction temperature within the rated range of 1350℃±50℃, resulting in uniform carbon black nucleation, narrow particle size distribution, and stable structure, increasing the product qualification rate to over 94%; simultaneously, the carbon black yield is increased from 63% in traditional processes to a maximum of 79%. Testing shows that the semi-reinforcing carbon black prepared by this invention has an iodine absorption value of 14±5 g / kg and a DBP absorption value of 47±6 cm³ / 100g, meeting the application requirements of high-end rubber products.

[0037] 4. Achieving safe and efficient in-situ utilization of hydrogen, a byproduct of pyrolysis: For the first time, a selective heat replenishment structure was designed in the carbon black reactor. By utilizing the order-of-magnitude difference in combustion rates between hydrogen and methane, the supplementary air is prioritized for combustion of hydrogen. This not only recovers the high calorific value of hydrogen to replenish the pyrolysis heat and reduces external fuel consumption, but also completely avoids contact between air and feed gas and carbon black. This solves the technical problems of hydrogen reuse in traditional processes, which easily damage the oxygen-free environment of pyrolysis and result in high equipment investment.

[0038] 5. Significantly increased hydrogen concentration in exhaust gas, greatly enhancing the value of byproduct hydrogen recovery: This invention utilizes combustion cracking space separation and precise selective heat replenishment technology to utilize some hydrogen for heat replenishment in situ, while significantly increasing the volume concentration of hydrogen in exhaust gas from 8.9% in traditional processes to 12.1-18.8%, while reducing the total dry exhaust gas volume by approximately 50%. This breakthrough completely reconstructs the utilization value system of byproduct hydrogen from multiple dimensions, including technology, economy, safety, environmental protection, and industrial model, significantly reducing the cost and difficulty of hydrogen recovery.

[0039] 6. The equipment is highly stable and widely adaptable: The volute design with the same direction of rotation ensures stable airflow in the furnace without turbulence or local overheating and coking, allowing the equipment to operate continuously and stably, significantly reducing maintenance costs. The equipment structure can be directly adapted to the transformation of existing semi-reinforced carbon black production lines, and can also be used in new projects without significant changes to the original process, resulting in low implementation costs. It is suitable for production needs of different capacity scales and can also be extended to the production of thermal cracking carbon black. Attached Figure Description

[0040] Figure 1 is a schematic axial cross-sectional view of the present invention;

[0041] Figure 2 is a schematic diagram of the radial section in the BB direction of Figure 1;

[0042] Figure 3 is a schematic diagram of the invention from the left side;

[0043] Figure 4 shows the invention. Figure 1 Schematic diagram of the radial section in the AA direction;

[0044] Figure 5 is a partial schematic diagram of direction C in Figure 1;

[0045] The numbers in the diagram are as follows: 1. Furnace body; 2. First raw material gas volute; 3. Second raw material gas volute; 4. Fuel gas volute; 5. Air volute; 6. Rectangular flow guide opening; 7. Supplementary air inlet; 8. Ignition gun assembly; 801. Ignition gun body; 802. High-temperature resistant sealing flange; 9. Medium air inlet; 10. Refractory layer; 11. First annular baffle; 12. Second annular baffle; 13. Third annular baffle; 14. Combustion zone; 15. First gradient pyrolysis reaction zone; 16. Second gradient pyrolysis reaction zone; 17. Selective supplementary heating zone; 18. Cooling device. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0047] The natural gas used in the embodiments and comparative examples of this invention is industrial natural gas with a methane volume fraction ≥97%; the combustion air used is filtered room temperature air; all gas flow rates are volume flow rates under standard conditions; product performance testing is performed in accordance with GB / T 3778-2021 "Carbon Black for Rubber" standard.

[0048] Example 1

[0049] like Figures 1-5As shown: A multi-stage volute-feed cyclone pyrolyzer includes a furnace body 1 and a volute assembly. One end of the furnace body 1 is the feed end, and the other end is the discharge end. The volute assembly consists of multiple coaxial and concentric nested volutes. The volute assembly is welded and fixed to the feed end of the furnace body 1, and the discharge end of the furnace body 1 has a cooling device 18. The volute assembly includes an air volute 5, a fuel gas volute 4, and at least one raw material gas volute arranged from the outside in. The air volute 5, fuel gas volute 4, and raw material gas volute are coaxial and concentrically nested. The air volute 5 is used to transport combustion air. The fuel gas volute 4 is used to transport fuel natural gas, and the feed gas volute is used to transport feed natural gas for cracking. The preferred volute assembly has four stages: in addition to the air volute 5 and the fuel gas volute 4, the assembly has two sets of feed gas volutes, including a first feed gas volute 2 at the center of the assembly and a second feed gas volute 3 between the first feed gas volute 2 and the fuel gas volute 4. These two layers of feed gas volutes enable staged feeding of the feed natural gas, improving cracking uniformity. The outer shell of the air volute 5 is connected to the furnace body 1. The material end is welded and fixed; each layer of the volute is separated by annular partitions, which include a first annular partition 11, a second annular partition 12, and a third annular partition 13. The first annular partition 11 is connected to the outer wall of the first raw material gas volute 2, the second annular partition 12 is connected to the outer wall of the second raw material gas volute 3, and the third annular partition 13 is connected to the outer wall of the fuel gas volute 4. In order to guide the airflow radially to achieve airflow pattern control, the first annular partition 11, the second annular partition 12, and the third annular partition are... The discharge end of 13 is an open funnel shape; the annular baffle is a 10mm stainless steel annular baffle, which seals and extends the flow channel of each volute to form an annular guide flow channel. At the same time, the multi-layer volute arrangement isolates the fuel natural gas and the raw material natural gas for cracking before entering the furnace body 1, and the annular baffle between each layer of volute guides the corresponding medium to the corresponding area; the overall material of the volute assembly is 310S high temperature resistant stainless steel, and the inner wall of the furnace body 1 is covered with a 100mm thick corundum refractory layer 10.

[0050] The outer walls of the air volute 5, fuel gas volute 4, first raw material gas volute 2, and second raw material gas volute 3 are each welded with an independent flange-type medium inlet port 9. Each medium inlet port 9 is connected to the flow channel of the corresponding volute, and the corresponding medium is introduced into the volute through the corresponding medium inlet port 9. The flow direction of all volutes is exactly the same, and the swirl angle between adjacent volutes of the four stages is 90°, so that the medium flows out of each layer and forms a unidirectional swirling flow, eliminating turbulent interference between different airflows.

[0051] Multiple rectangular flow guide holes 6 are evenly distributed on the circumference of the inner cylinder of the air volute 5. These rectangular flow guide holes 6 penetrate the inner cylinder of the air volute 5, connecting it to the fuel gas volute 4. Specifically, there are four rectangular flow guide holes 6, which are evenly spaced at 90° intervals along the circumference of the inner cylinder of the air volute 5. The rectangular flow guide holes 6 are also axially equidistant. The dimensions of a single rectangular flow guide hole 6 are 120mm × 50mm (length-to-width ratio 2.4:1). By connecting the air volute 5 and the fuel gas volute 4 through the rectangular flow guide holes 6, some of the combustion air seeps from the air volute 5 into the fuel gas volute 4, allowing the combustion air and fuel natural gas to be premixed.

[0052] The furnace body 1 is cylindrical. From the feed end to the discharge end, the furnace body 1 is divided into a combustion zone 14, a first gradient pyrolysis reaction zone 15, a second gradient pyrolysis reaction zone 16, and a selective reheating zone 17 according to their functions. The air volute 5, fuel gas volute 4, first raw material gas volute 2, and second raw material gas volute 3 are open at their respective functional areas, and the medium is transported to the corresponding area through corresponding annular baffles. Specifically, the end of the third annular baffle 13 extends to the entrance of the combustion zone 14, the end of the second annular baffle 12 extends to the first gradient pyrolysis reaction zone 15, and the end of the first annular baffle 11 extends to the second gradient pyrolysis reaction zone 16. Zone 16, meaning the area from the end of the third annular baffle 13 to the end of the second annular baffle 12 within the furnace body 1, is the combustion zone, specifically the 0-600mm section from the feed end of the furnace body 1. The area from the end of the second annular baffle 12 to the end of the first annular baffle 11 is the first gradient pyrolysis reaction zone 15, and the area from the end of the first annular baffle 11 to the selective reheating zone 17 is the second gradient pyrolysis reaction zone 16. The first gradient pyrolysis reaction zones 15 and 16 are located 600-1900mm downstream of the feed end of the furnace body 1, while the selective reheating zone 17 is located 1500-2500mm downstream of the feed end of the furnace body 1. The annular baffles guide the medium to each reaction zone, maximizing its utilization.

[0053] An ignition gun assembly 8 is embedded in the central axial position of the first raw material gas volute 2. The ignition gun assembly 8 is used for ignition and furnace baking during the equipment start-up phase. The ignition gun assembly 8 includes an ignition gun body 801 and a high-temperature resistant sealing flange 802. The front end of the ignition gun body 801 extends into the furnace body 1, and the rear end is sealed to the end cap of the first raw material gas volute 2 through the high-temperature resistant sealing flange 802. The high-temperature resistant sealing flange 802 seals the ignition gun body 801 to the first raw material gas volute 2, thereby effectively preventing medium leakage during pyrolysis. The front end of the ignition gun body 801 extends into the combustion zone 14.

[0054] The furnace body 1 has two DN50 supplementary air inlets 7, symmetrically distributed 180° around the circumference of the furnace body. The supplementary air inlets 7 are tubular structures, with their inlet ends extending to the outer wall of the furnace body 1 and welded to the furnace body 1 via standard connecting flanges. The outlet ends of the supplementary air inlets 7 extend to the selective heat replenishment zone 17 inside the furnace body 1. The supplementary air inlets 7 adopt a tangential offset design, with the inlet direction consistent with the rotation direction of the volute assembly. Furthermore, the inlet end of the supplementary air inlet 7 forms a 30°-60° angle with the swirling pyrolysis channel at the center of the furnace, preferably a 45° angle. Through the supplementary air inlets 7, staged heat replenishment can be achieved, allowing the supplementary air to be precisely injected into the outer ring hydrogen enrichment zone of the pyrolysis channel, thereby optimizing the temperature field distribution inside the furnace. Based on the production of 1 ton of carbon black, the above-mentioned 4-stage volute-feed swirling pyrolysis unit is used to produce carbon black from natural gas through pyrolysis. This method is suitable for conventional continuous production lines. The specific steps are as follows:

[0055] Start the oven:

[0056] First, close all medium inlet valves and open ignition gun assembly 8 for ignition. Introduce a small amount of fuel natural gas and combustion air into ignition gun assembly 8. Heat the furnace according to the process temperature rise curve to prevent cracking of the refractory layer of furnace body 1 due to uneven thermal stress, while ensuring uniform heating of the volute assembly. After raising the furnace temperature to 800℃, introduce combustion air into the air volute 5 and fuel natural gas into the fuel gas volute 4. Continue heating the furnace according to the process temperature rise curve, raising the furnace temperature to the rated reaction temperature of 1350℃. After the temperature reaches the target and stabilizes for two hours, close the open flame of ignition gun assembly 8 (or ignition gun assembly 8 can be closed after the furnace temperature reaches 800℃). After the furnace reaches the rated reaction temperature, lock the high-temperature sealing flange 802 at the rear end of ignition gun assembly 8, and switch the pyrolyzer to continuous production mode.

[0057] Staged feeding and complete combustion:

[0058] Fuel natural gas is continuously introduced into the fuel gas volute 4 at a flow rate of 1750 Nm³ / ton of carbon black; combustion air is continuously introduced into the air volute 5 at a total flow rate of 16695 Nm³ / ton of carbon black (1.05 times the theoretical air volume required for complete combustion of fuel natural gas); 25%-35% of the combustion air enters the gas volute through the rectangular guide opening 6 and premixes with the fuel natural gas to form premixed gas; the remaining 65%-75% of the combustion air enters the combustion zone 14 through the flow channel of the air volute 5, mixes with the premixed gas and is completely combusted, generating high-temperature exhaust gas at approximately 1750℃-1800℃. This staged air distribution method ensures complete combustion of fuel natural gas, while strictly controlling the flow rate of combustion air and the premixing ratio ensures that the oxygen content in the flue gas after combustion is less than 0.1%, preventing excess oxygen from entering the downstream cracking zone to oxidize the feed gas.

[0059] Gradient laminar flow decomposition:

[0060] Raw material natural gas is introduced into the second raw material gas volute 3 at a flow rate of 1500 Nm³ / ton of carbon black; simultaneously, raw material natural gas is introduced into the first raw material gas volute 2 at a flow rate of 950 Nm³ / ton of carbon black, for a total raw material gas flow rate of 2450 Nm³ / ton of carbon black. The high-temperature residual gas in the combustion zone 14 enters the first gradient cracking reaction zone 15 and the second gradient cracking reaction zone 16 in a right-handed swirling state, enveloping the raw material natural gas ejected from the second raw material gas volute 3. The raw material natural gas ejected from the second raw material gas volute 3 envelops the raw material natural gas ejected from the first raw material gas volute 2, forming a continuous and uniform annular high-temperature gas jacket. The raw material natural gas is heated layer by layer from the outside to the inside, causing the raw material natural gas to undergo a progressive thermal cracking reaction in an oxygen-free laminar flow state, generating carbon black and hydrogen-containing cracking gaseous products. The high-temperature waste gas heats the feedstock natural gas layer by layer from the outside in through radiation and convection heat exchange: the outer layer of feedstock gas first reaches the cracking temperature of 1350℃ to begin the reaction, and the inner layer of feedstock gas then gradually heats up, forming a gradient cracking reaction field that is "progressive" from the outside in. An oxygen-free or extremely low-oxygen environment is maintained throughout the process to ensure that methane undergoes a directional thermal cracking reaction with no ineffective combustion losses. Simultaneously, the high-temperature waste gas indirectly exchanges heat with the inner layer of feedstock gas through the volute wall, preheating the feedstock natural gas to 300-400℃ before it enters the furnace, further reducing fuel consumption.

[0061] Selective heat supplementation:

[0062] In the gradient cracking reaction zone, the feedstock natural gas can achieve 60%-80% cracking. The cracked gaseous products flow into the selective reheating zone 17 through the cracking channel. Supplementary air is introduced through the supplementary air inlet 7, and the total flow rate of the supplementary air is 30%-40% of the theoretical air required for the complete combustion of the cracked gaseous products. Taking advantage of the fact that hydrogen burns much faster than methane, the supplementary air preferentially undergoes partial combustion with the hydrogen in the cracking products, rapidly releasing heat. This promotes further cracking of the remaining uncracked natural gas in the outer layer and, through radiation and convection, provides a supplementary heat source for the cracking of the feedstock natural gas ejected from the first feedstock gas volute 2, maintaining the cracking reaction temperature stable at 1350℃±50℃. Since the air intake is strictly controlled within the hydrogen combustion equivalent, there is no free oxygen remaining after the reaction, completely avoiding the oxidation loss of the feedstock natural gas and the generated carbon black.

[0063] Rapid cooling termination and product collection:

[0064] After the pyrolysis reaction is completed, the product enters the cooling device 18, where it is rapidly cooled to below 700-800℃ by spraying quench water to terminate the reaction, preventing excessive growth and graphitization of carbon black particles and ensuring uniform particle size distribution of the product. The quenched gas-solid mixture then sequentially enters a cyclone separator and a bag filter (not shown in the figure) for gas-solid separation to obtain solid carbon black product. The solid carbon black product is collected, granulated, and packaged. The gaseous products are mainly unreacted methane and hydrogen, which, after purification, can be reused as fuel gas in the combustion zone or purified hydrogen can be sold as a byproduct, further improving the system's energy utilization rate and economic benefits.

[0065] The results of this embodiment are as follows: the total natural gas consumption for producing one ton of carbon black is 4000 Nm³, which is 30% lower than that of the traditional process; the carbon black yield is 79%, which is 13 percentage points higher than that of the traditional process; the product iodine absorption value is 14±5 g / kg, the DBP absorption value is 47±6 cm³ / 100g, which meets the standard for natural gas semi-reinforcing carbon black; the product qualification rate is 99%, and all indicators are far superior to those of the traditional process.

[0066] Working principle:

[0067] Premixed combustion: Multiple rectangular guide openings 6 on the air volute 5 divide the combustion air into two paths after entering the air volute 5: one path seeps into the fuel gas volute 4 through the rectangular guide openings 6, achieving slight premixing with the fuel natural gas, which plays a role in stabilizing the flame and ensuring complete combustion; the other path flows along the entire flow channel formed by the air volute 5 and the third annular baffle 13, and completely merges with the premixed gas in the combustion zone 14 at the outlet of the third annular baffle 13, achieving precise air-fuel combustion. The intake air ratio of fuel gas to air is strictly controlled to be close to or equal to the stoichiometric ratio of complete methane combustion (1 volume of CH4 corresponds to 9.52-9.996 volumes of air), ensuring that the fuel gas can achieve near-complete combustion while preventing excessive oxygen from entering the gradient cracking reaction zone, thus avoiding oxidation of the feed gas and carbon black, which would affect the yield.

[0068] Gradient laminar flow pyrolysis: The high-temperature waste gas generated from the complete combustion of fuel gas enters the first gradient pyrolysis reaction zone 15 and the second gradient pyrolysis reaction zone 16 in a swirling state with the feed gas from the combustion zone 14. It surrounds the feed gas ejected from the second feed gas volute 3, which in turn surrounds the feed gas ejected from the first feed gas volute 2, forming a swirling pyrolysis channel. The high-temperature waste gas forms a stable high-temperature heat source on the outer layer, achieving gradual gradient heating from the periphery to the center through radiation and convection heat exchange. The pyrolysis reaction proceeds layer by layer from the outside to the inside simultaneously. The entire process maintains a stable laminar flow state of the feed gas, strictly isolating it from air mixing, ensuring the directional pyrolysis of methane to produce carbon black and hydrogen, with no ineffective combustion losses. Simultaneously, the high-temperature flue gas indirectly exchanges heat with the inner feed gas through an annular baffle, preheating the feed gas and further improving heat utilization.

[0069] Selective supplementary heating: The supplementary air inlet 7 on the furnace body 1 adopts a tangential offset design. Its air intake direction is at an angle of 30°-60° with the swirling cracking channel in the center of the furnace. This allows the supplementary air to be precisely injected into the outer ring gas phase region of the cracking channel, i.e., the high-temperature residual gas. This region is the enrichment area of ​​hydrogen, a cracking byproduct (hydrogen gas fraction can reach 50%-75%). At the same time, it avoids the air directly impacting the core flow of the incompletely cracked feed gas in the inner layer. From the flow field design, it eliminates the premature contact between oxygen and feed methane.

[0070] After supplemental air is introduced into the later stages of the pyrolysis reaction, the three fundamental differences in the combustion kinetics of hydrogen and methane are utilized to achieve in-situ selective combustion and reheating without separation:

[0071] First, the difference in ignition energy: the minimum ignition energy of hydrogen is only 0.017 mJ, far lower than that of methane (0.28 mJ, a difference of 16.5 times). In the high-temperature environment of 1350℃ in the pyrolysis zone, hydrogen can spontaneously combust upon contact with oxygen without any external ignition source; while the spontaneous combustion induction period of methane under the same conditions is more than 12 times that of hydrogen, making it unable to compete with hydrogen for oxygen.

[0072] Second, the reaction rate difference: the laminar flame propagation speed of hydrogen is about 2.7 m / s, which is 7.1 times that of methane (0.38 m / s); at a high temperature of 1350℃, the oxidation reaction rate constant of hydrogen is 3 orders of magnitude higher than that of methane, and the combustion reaction is completed in milliseconds.

[0073] Third, the difference in diffusion rate: the molecular diffusion coefficient of hydrogen is 4 times that of methane, allowing it to mix and react with supplementary air more quickly.

[0074] The synergistic effect of these three characteristics allows the oxygen in the supplemental air to preferentially and almost completely react with the hydrogen in the cracked gaseous products—the oxygen molecules are completely consumed by the hydrogen in the outer ring before they can reach the inner uncracked methane through diffusion, thus achieving selective separation and combustion of hydrogen and methane from a reaction kinetics perspective.

[0075] The amount of supplemental air introduced is strictly controlled to be 30%-40% of the theoretical stoichiometric air volume required for the complete combustion of hydrogen in the pyrolysis gaseous products, thus forming a precise oxygen-deficient heating condition:

[0076] The heat recovery side: The high calorific value (10.8 MJ / Nm³) released rapidly by hydrogen combustion accurately compensates for the temperature decay caused by the endothermic reaction of methane cracking in the later stage of the cracking reaction, and keeps the temperature of the entire cracking zone stable within the optimal range of 1350℃±50℃, avoiding uneven carbon black particle size distribution and decreased cracking yield due to temperature fluctuations.

[0077] Anti-oxidation side: Since the air intake is strictly controlled within the hydrogen combustion equivalent, there is no free oxygen remaining after the reaction, which fundamentally eliminates the contact between the remaining oxygen and the un-cracked raw material natural gas and the generated carbon black particles in the inner layer, completely avoiding ineffective oxidation of raw materials and carbon black burn-off.

[0078] Example 2

[0079] A simplified solution using a three-layer volute assembly (suitable for the transformation of small and medium-capacity production lines).

[0080] This embodiment is basically the same as Embodiment 1, except that the first raw material gas volute 2 and the second raw material gas volute 3 are combined in the volute assembly, retaining only one set of raw material gas volutes. This embodiment has a simpler structure, lower manufacturing cost, and is suitable for low-cost retrofitting of existing small and medium-capacity production lines.

[0081] Using the pyrolyzer of this embodiment for the production of carbon black from natural gas, with a production target of 1 ton of carbon black, the specific parameters are as follows:

[0082] The fuel natural gas feed rate is 2000 Nm³ / ton of carbon black, and the total combustion air flow rate is 19080 Nm³ / ton of carbon black (1.02 times the theoretical air volume required for complete combustion of fuel natural gas).

[0083] The total feedstock natural gas flow rate is 2800 Nm³ / ton of carbon black, all of which is introduced through the feedstock gas volute.

[0084] The supplementary air intake is 30% of the theoretical air required for the complete combustion of the pyrolysis gaseous products;

[0085] The rated pyrolysis reaction temperature is 1350℃.

[0086] The results of this embodiment are as follows: the total natural gas consumption for producing 1 ton of carbon black is 4800 Nm³, which is 20% lower than that of the traditional process; the carbon black yield is 71%, which is 8 percentage points higher than that of the traditional process; and the equipment modification cost is only 50% of that of new equipment, making it suitable for the upgrade needs of small and medium-sized production lines.

[0087] Example 3

[0088] A four-layer optimization scheme is adopted (extended application to adapt to the production line of pyrolysis carbon black products).

[0089] The difference between this embodiment and Embodiment 1 is that the supplementary air inlet 7 is removed, the rated pyrolysis reaction temperature is optimized to 1250℃, and the excess combustion air coefficient is precisely controlled to 1.00 (i.e., the combustion air is 1.00 times the theoretical amount of air required for the complete combustion of fuel natural gas), maximizing the reduction of inert nitrogen introduction, further increasing the hydrogen concentration in the tail gas, and maximizing the value of by-product hydrogen.

[0090] The method for producing carbon black from natural gas using the pyrolysis unit in this embodiment, based on the production of 1 ton of carbon black, has the following specific parameters:

[0091] The fuel natural gas feed rate is 1450 Nm³ / ton of carbon black, and the total combustion air flow rate is 13804 Nm³ / ton of carbon black (1.0 times the theoretical air volume required for complete combustion of fuel natural gas); the total feedstock natural gas feed rate is 2350 Nm³ / ton of carbon black, of which 1450 Nm³ / ton of carbon black is fed into the second feedstock gas volute, and 950 Nm³ / ton of carbon black is fed into the first feedstock gas volute; the rated pyrolysis reaction temperature is 1250℃. The operating results of this embodiment are as follows: the total natural gas consumption for producing 1 ton of carbon black is 3800 Nm³, a reduction of 36.7% compared to the traditional process; the carbon black yield is 73%; the product iodine absorption value is 11 g / kg; the DBP absorption value is 35 cm³ / 100g, meeting the national standard for N990 carbon black; the product qualification rate is 98%, which can meet the application requirements of high-end rubber products.

[0092] Comparative Example 1: Traditional Single-Pass Feeding Process

[0093] To verify the technical effect of the present invention, a comparative experiment was conducted using a conventional single-feed reactor. The raw material natural gas and the fuel natural gas were injected into the furnace through the same channel. The excess combustion air coefficient was 1.15, and the reaction temperature was controlled at 1350°C. The key raw material conditions are shown in Table 1, and the other conditions are the same as in Example 1.

[0094] Experimental results: The total natural gas consumption for producing 1 ton of carbon black is 6000 Nm³, and the carbon black yield is 63%, which is far lower than the technical indicators of the present invention.

[0095] Table 1. Technical Effects, Process Conditions, and Technical Effects of Each Embodiment and Comparative Example

[0096] Fuel natural gas volume (Nm³ / ton carbon black) 1750 2000 1450 — Excess Combustion Air Coefficient 1.05 1.02 1.00 1.15 Raw material natural gas quantity (Nm³ / ton carbon black) 2450 2800 2350 — Total natural gas consumption (Nm³ / ton carbon black) 4200 4800 3800 6000 Comprehensive energy consumption (kgce / ton of carbon black) 516.2 589.9 467.0 737.4 Energy consumption reduction compared to traditional processes 30.0% 20.0% 36.7% — Rated pyrolysis temperature (°C) 1350 1350 1250 1350 Carbon black yield (%) 76 71 73 63 Corresponding product model Natural gas semi-reinforcing carbon black Natural gas semi-reinforcing carbon black N990 Natural gas semi-reinforcing carbon black Product pass rate (%) 99 96 98 92

[0097] Table 1 shows that the total natural gas consumption for preparing semi-reinforcing carbon black using the pyrolyzer of this invention is 3800-4200 Nm³ / ton, with a comprehensive energy consumption of 467.0-516.2 Nm³ / ton, which is significantly lower than the total natural gas consumption of 6000 Nm³ / ton and the comprehensive energy consumption of 737.4 Nm³ / ton in Comparative Example 1. The carbon black recovery rate of this application reaches 71%-76%, and the product qualification rate is 96%-98%, while the carbon black recovery rate of Comparative Example 1 is only 63%, and the product qualification rate is 92%. It is evident that the technical solution of this invention is significantly superior to the prior art of Comparative Example 1.

[0098] Comparing Examples 1-3, it can be seen that Example 1 has a high product yield and high pass rate, and its energy consumption reduction compared to the traditional process is in the middle among the three examples, making it suitable for continuous production lines with conventional capacity. Compared to the traditional process, Example 2 has improved carbon black yield and product pass rate, but its energy consumption reduction is relatively low, making it suitable for small to medium capacity production lines. Example 3, due to the precise control of the excess combustion air coefficient to 1.00, belongs to the thermal cracking carbon black method. It is made from 100% natural gas as raw material through high-temperature thermal cracking under air-isolated conditions, and the resulting product is N990 in the ASTM standard, which can be used as a functional filler carbon black. Examples 1 and 2 are made from natural gas as raw material through a gas furnace process of partial combustion and cracking at 1350℃, belonging to semi-reinforcing carbon black, which is a classic reinforcing filler material. In actual production, the corresponding process can be selected according to the application field or scenario of the carbon black.

[0099] Industrial applicability

[0100] The multi-stage volute feed cyclone pyrolyzer and the method for producing carbon black from natural gas pyrolysis provided by this invention can be directly applied to the industrial continuous production of semi-reinforcing carbon black. It is suitable for both newly built large-scale carbon black production lines and low-cost retrofitting of existing traditional production lines. It has the advantages of low energy consumption, high yield, stable product quality, and reliable equipment operation. It is especially suitable for carbon black production projects in areas with abundant natural gas resources, and has significant economic benefits and industry promotion value.

[0101] Although the invention has been described herein with reference to illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter combination within the scope of this disclosure. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A multi-stage volute-feed hydrocyclone pyrolyzer, characterized in that: The furnace includes a cylindrical furnace body (1) and a volute assembly. The furnace body (1) has a combustion zone (14) and a pyrolysis reaction zone. The volute assembly includes an air volute (5), a fuel gas volute (4), and at least one raw material gas volute, which are concentrically nested from the outside to the inside. All volutes have the same flow direction. The air volute (5), the fuel gas volute (4), and the raw material gas volute each have a medium inlet port (9) that is connected to their flow channels. The air volute (5) is fixedly connected to the feed end of the furnace body (1). One end of the air volute (5) and the fuel gas volute (4) are open and the end extends to the combustion zone. One end of the raw material gas volute is open and the end extends to the pyrolysis reaction zone. Multiple flow guide holes are evenly distributed on the circumference of the inner cylinder of the air volute (5). The air volute (5) and the fuel gas volute (4) are connected through the flow guide holes.

2. The multi-stage volute-feed cyclone pyrolyzer according to claim 1, characterized in that, The flow guiding direction of each layer of the volute assembly is either right-handed or left-handed, and the swirling angle between adjacent volutes is the quotient obtained by the number of stages (360°).

3. The multi-stage volute feed hydrocyclone pyrolyzer according to claim 2, characterized in that: The raw material gas volute includes a second raw material gas volute (3) and a first raw material gas volute (2) nested within the second raw material gas volute (3); the pyrolysis reaction zone of the furnace body (1) includes a first gradient pyrolysis reaction zone (15) near the combustion zone (14) and a second gradient pyrolysis reaction zone (16) behind the first gradient pyrolysis reaction zone (15); the end of the second raw material gas volute (3) extends to the first gradient pyrolysis reaction zone (15), and the end of the first raw material gas volute (2) extends to the second gradient pyrolysis reaction zone (16).

4. The multi-stage volute feed cyclone pyrolyzer according to claim 3, characterized in that: The furnace body (1) also has a selective heat supplement zone (17). The selective heat supplement zone (17) is located at the rear of the second gradient pyrolysis reaction zone (16). The selective heat supplement zone (17) is provided with at least two supplementary air inlets (7). The supplementary air inlets (7) are evenly arranged on the circumference of the furnace body. The supplementary air inlets (7) adopt a tangential offset design. The air intake direction is consistent with the rotation direction of the volute assembly. The air intake end of the supplementary air inlet (7) forms an angle of 30°-60° with the swirling pyrolysis channel in the center of the furnace.

5. The multi-stage volute feed cyclone pyrolyzer according to claim 4, characterized in that: An ignition gun assembly (8) is embedded in the center axial position of the first raw material gas volute (2). The ignition gun assembly (8) is sealed to the first raw material gas volute (2). The front end of the ignition gun body (801) extends to the combustion zone (14).

6. The multi-stage volute feed hydrocyclone pyrolyzer according to claim 4, characterized in that: The combustion zone is the 0-600mm section of the feed end of the furnace body (1). The first gradient pyrolysis reaction zone (15) and the second gradient pyrolysis reaction zone (16) are located 600-1900mm downstream of the feed end of the furnace body (1). The selective reheating zone (17) is located 1500-2500mm downstream of the feed end of the furnace body (1).

7. The multi-stage volute feed cyclone pyrolyzer according to claim 1, characterized in that: The number of flow guiding openings is four, which are evenly distributed along the circumference of the inner cylinder of the air volute (5) and are equally spaced in the axial direction. The length-to-width ratio of a single rectangular flow guiding opening is not less than 2:1, and the total area of ​​all flow guiding openings accounts for 8%-12% of the cross-sectional area of ​​the inner cylinder of the air volute.

8. The multi-stage volute feed cyclone pyrolyzer according to claim 3, characterized in that: The air volute (5), fuel gas volute (4), and raw material gas volute are all provided with annular baffles at their ends, and each volute extends to the corresponding area through the annular baffles.

9. A method for producing carbon black from natural gas by pyrolysis, using the multi-stage volute feed cyclone pyrolyzer as described in any one of claims 1-8, comprising the following steps: (1) Start the furnace: Ignite the furnace by igniting the ignition gun assembly, introduce combustion air into the air volute, and introduce fuel natural gas into the fuel gas volute. After the air and fuel natural gas are premixed, they burn to form a stable flame. Bake the furnace to the rated reaction temperature of 1200-1500℃ according to the heating curve given by the process. (2) Staged feeding and complete combustion: Fuel natural gas is continuously fed into the fuel gas volute, and combustion air is continuously fed into the air volute; 25%-35% of the combustion air enters the fuel gas volute through the guide opening and is premixed with the fuel natural gas to form premixed gas. The remaining combustion air enters the combustion zone through the air volute channel and is mixed with the premixed gas for complete combustion, generating high-temperature waste gas at 1750-1800℃. (3) Gradient laminar flow pyrolysis: The high-temperature residual gas enters the gradient pyrolysis reaction zone from the combustion zone in a swirling state in the same direction as the raw material natural gas. It surrounds the raw material natural gas ejected from the raw material gas volute and heats the raw material natural gas layer by layer from the outside to the inside through radiation and convection heat exchange, so that the raw material natural gas undergoes a progressive thermal pyrolysis reaction in an oxygen-free laminar flow state, generating carbon black and hydrogen-containing pyrolysis gaseous products. (4) Selective supplementary heating: After the cracked gaseous products enter the selective supplementary heating zone with the material flow, supplementary air is introduced through the supplementary air inlet. Taking advantage of the characteristic that the flame propagation speed of hydrogen is much faster than that of methane, the supplementary air preferentially undergoes partial combustion with the hydrogen in the cracked gaseous products, and the heat released provides a supplementary heat source for the cracking of the remaining uncracked natural gas. (5) Product collection: The product after the pyrolysis reaction is completed is rapidly cooled to terminate the reaction and separated into gas and solid to obtain carbon black product.

10. The method for producing carbon black from natural gas pyrolysis according to claim 9, characterized in that: In step (2), the total amount of combustion air introduced is 1.0-1.05 times the theoretical amount of air required for the complete combustion of fuel natural gas; the amount of fuel natural gas introduced is 1400-2200 Nm³ / ton of carbon black; In step (3), the raw natural gas is divided into two streams and introduced into the two layers of raw gas volutes on the radial inner side. The volume ratio of the two streams of raw gas is (3.5-4.5):(5.5-6.5), and the total amount of raw natural gas introduced is 2150-3000 Nm³ / ton of carbon black. In step (4), the amount of supplementary air introduced is 30%-40% of the theoretical chemical equivalent air required for the complete combustion of the pyrolysis gaseous products.

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