Hydrogen-based decomposition ammonia reburner and combustion method

Abstract

This invention relates to the field of burners, specifically a hydrogen-based ammonia decomposition reburner. The burner includes a preheating decomposition combustion chamber with an internal cavity; a Brownian gas pipe passes through the chamber wall of the preheating decomposition combustion chamber, with its output end located inside the cavity; a first igniter passes through the chamber wall of the preheating decomposition combustion chamber, with its ignition head near the output end of the Brownian gas pipe; the output end of an ammonia pipe communicates with the interior of the cavity; the input end of a delivery pipe communicates with the interior cavity of the preheating decomposition combustion chamber; and the ignition head of a second igniter is near the output end of the delivery pipe. This burner utilizes the active free radicals generated by a hydrogen flame as a catalyst. By adjusting the ratio of the hydrogen-oxygen mixture produced by water electrolysis to fuel ammonia and the combustion conditions, the combustion of ammonia is converted into the combustion of hydrogen, nitrogen, and possibly undecomposed ammonia. This technology aims to improve combustion efficiency, reduce nitrogen oxide emissions, and improve overall energy utilization. This invention also proposes a method for hydrogen-based ammonia decomposition reburning.

Description

Technical Field

[0001] This invention relates to the field of burners, and in particular to hydrogen-based ammonia decomposition reburners and combustion methods. Background Technology

[0002] With the increasing global demand for energy transition and green, low-carbon energy, the potential of hydrogen energy as a clean energy source is increasingly recognized. Hydrogen does not produce carbon dioxide during combustion, making it an important means of achieving a low-carbon economy. However, the storage and transportation of hydrogen remain major obstacles to its widespread application. To address this issue, ammonia (NH3) has been extensively studied as a hydrogen carrier. Ammonia has advantages such as high hydrogen content, ease of liquefaction, and storage, but challenges remain in the efficient utilization of ammonia, particularly in its decomposition and combustion technologies.

[0003] Currently, ammonia pre-decomposition combustion technology mainly faces the following problems: First, ammonia has low combustion efficiency and easily produces harmful emissions such as nitrogen oxides (NOx); second, ammonia decomposition usually requires high temperatures, leading to increased energy consumption and equipment complexity. Therefore, developing a high-efficiency ammonia burner that can effectively decompose ammonia and achieve clean combustion is a current research focus. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a hydrogen-based ammonia decomposition reburner. This burner utilizes active free radicals generated by a hydrogen flame as a catalyst and optimizes the ammonia combustion process by adjusting the ratio of the hydrogen-oxygen mixture produced by water electrolysis to the fuel ammonia and the combustion conditions. This technology aims to improve combustion efficiency, reduce nitrogen oxide emissions, and enhance overall energy utilization. This invention also proposes a hydrogen-based ammonia decomposition reburning method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] Hydrogen-based ammonia decomposition reburner, including

[0007] A preheating decomposition combustion chamber, wherein the interior of the preheating decomposition combustion chamber has a cavity;

[0008] Brown's tube, which passes through the wall of the preheating decomposition combustion chamber and has its outlet end located inside the cavity;

[0009] The first igniter passes through the wall of the preheating decomposition combustion chamber, and the ignition head of the first igniter is close to the output end of the Brownian tube.

[0010] An ammonia gas pipe, the output end of which is connected to the interior of the cavity;

[0011] A delivery pipeline, the input end of which is connected to the inner cavity of the preheating decomposition combustion chamber;

[0012] The second igniter has its ignition head located near the output end of the delivery pipeline.

[0013] Preferably, there are multiple ammonia pipes, with the output end of the ammonia pipes facing the Brownian pipes, and the ammonia pipes are distributed in a ring array in the preheating decomposition combustion chamber.

[0014] Preferably, the ammonia gas pipe is located below the outlet end of the Brown gas pipe.

[0015] Preferably, the delivery pipeline has a flame-retardant core inside.

[0016] Preferably, the preheating decomposition combustion chamber is a vertical tubular body with closed upper and lower ends, the Brown gas pipe is installed at the lower end of the preheating decomposition combustion chamber, and the input end of the delivery pipeline is connected to the upper end of the preheating decomposition combustion chamber.

[0017] Preferably, the top of the preheating decomposition combustion chamber is connected to a tubular mixed-gas combustion chamber, the middle of the mixed-gas combustion chamber has a mixed-gas disc, the middle of the mixed-gas disc has a through hole, the top end of the delivery pipeline is connected to the through hole of the mixed-gas disc, the second igniter is installed in the mixed-gas combustion chamber, and the ignition head of the second igniter is located above the through hole.

[0018] Preferably, the air-fuel combustion chamber further includes an air pipe that communicates with the interior of the air-fuel combustion chamber and is located below the air-fuel mixing disc.

[0019] Preferably, the mixing disc is provided with an inverted cup-shaped air supply cap at the corresponding through hole, the top surface of the air supply cap has a number of first air supply holes, and the outer peripheral wall of the air supply cap is provided with a number of second air supply holes.

[0020] Preferably, the mixing disc has several vertically penetrating internal inclined holes arranged in a ring array around the axis of the mixing disc.

[0021] Preferably, the outer peripheral surface of the mixing disc has a plurality of vertically penetrating outer grooves, and the outer grooves and the inner wall of the mixing combustion chamber form an outer hole, and the outer hole is distributed in a ring array with the axis of the mixing disc as the center.

[0022] On the other hand, the present invention also proposes a method for hydrogen-based decomposition and re-combustion of ammonia, comprising:

[0023] Brown gas is introduced into a closed space and ignited. Ammonia is introduced during the ignition of the Brown gas. The ammonia is heated and activated during the combustion of the Brown gas.

[0024] The products of the Brown gas combustion and the high-temperature ammonia gas are extracted and an oxidizing gas is added to ignite the above mixture to achieve the effect of ammonia combustion.

[0025] The beneficial effects of using this invention are:

[0026] The hydrogen-based ammonia reburner proposed in this invention completes Brownian gas combustion in a preheated decomposition combustion chamber. Ammonia gas is introduced through an ammonia pipe around the Brownian gas flame. During the Brownian gas combustion process, the ammonia gas is heated and activated. The combustion products of the Brownian gas and the high-temperature ammonia gas are then guided to the mixed-gas combustion chamber for ignition, completing the controlled combustion of ammonia. This invention, by achieving highly efficient hydrogen-ammonia combustion technology, can significantly improve the application potential of ammonia as a hydrogen energy carrier, promoting the practical application of hydrogen energy and renewable energy. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a hydrogen-based ammonia decomposition reburner.

[0028] Figure 2 for Figure 1 Enlarged view of a portion of point A in the middle.

[0029] Figure 3 This is a top view of the mixing disc.

[0030] The reference numerals in the figures include:

[0031] 10-Preheating decomposition combustion chamber, 11-Explosion vent, 12-Brown gas pipe, 121-Burn nozzle, 13-Ammonia gas pipe, 14-First igniter;

[0032] 20-Gas-fuel combustion chamber, 21-Air delivery inner cavity, 22-Delivery pipeline, 221-Flame arrestor core, 23-Air pipe, 24-Gas-fuel mixing disc, 241-Gas delivery cap, 242-First gas delivery port, 243-Second gas delivery port, 244-Inner oblique hole, 245-Outer hole, 25-Second igniter, 26-Flame opening. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this technical solution clearer, the following detailed description, in conjunction with specific embodiments, further illustrates this technical solution. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of this technical solution.

[0034] To address the difficulty in controlling the ammonia decomposition process in existing technologies, such as... Figure 1As shown, a hydrogen-based ammonia decomposition reburner is proposed. Specifically, the hydrogen-based ammonia decomposition reburner includes two parts: a preheating decomposition combustion chamber 10 and a mixed-gas combustion chamber 20. The preheating decomposition combustion chamber 10 is a cylindrical tubular structure, vertically arranged, and has flange structures at both the upper and lower ends. The preheating decomposition combustion chamber 10 is sealed by the flange structure, and a Brown gas pipe 12 is installed at the position of the flange structure. The Brown gas pipe 12 passes through the preheating decomposition combustion chamber 10, and its output end is located inside the preheating decomposition combustion chamber 10. The Brown gas pipe 12 can stably and continuously output Brown gas into the preheating decomposition combustion chamber 10. A burner nozzle 121 is provided at the output end of the Brown gas pipe 12.

[0035] One to four ammonia pipes 13 are provided on the outer peripheral wall of the preheating decomposition combustion chamber 10. The ends of the ammonia pipes 13 are welded to the outer peripheral wall of the preheating decomposition combustion chamber 10. The ammonia pipes 13 are used to stably supply ammonia gas to the preheating decomposition combustion chamber 10. In this embodiment, there are four ammonia pipes 13, which are arranged in an array with the axis of the preheating decomposition combustion chamber 10 as the center, and radially arranged with the axis of the preheating decomposition combustion chamber 10 as the center.

[0036] Preferably, the ammonia pipe 13 is positioned lower than the burner 121.

[0037] An explosion vent 11 is provided near the upper end of the outer peripheral wall of the preheating decomposition combustion chamber 10. This explosion vent 11 is used to relieve pressure and prevent explosion when the pressure inside the preheating decomposition combustion chamber 10 is too high. In some embodiments, a transparent observation window, such as a quartz observation window, can also be provided on the outer peripheral wall of the preheating decomposition combustion chamber 10 to facilitate observation of the internal conditions of the preheating decomposition combustion chamber 10. A first igniter 14 is also installed on the outer peripheral wall of the preheating decomposition combustion chamber 10. The ignition head of the first igniter 14 is close to the burner nozzle 121 and is used to ignite the Brown gas so that the Brown gas burns inside the preheating decomposition combustion chamber 10.

[0038] In this embodiment, the mixed-gas combustion chamber 20 is also a tubular structure, and its lower end is sealed to the upper end of the preheating decomposition combustion chamber 10 via a flange structure. A partition is provided between the upper end of the preheating decomposition combustion chamber 10 and the lower end of the mixed-gas combustion chamber 20, which is used to divide the interior of the mixed-gas combustion chamber 20 and the preheating decomposition combustion chamber 10 into two independent cavities.

[0039] In the mixed-gas combustion chamber 20, a mixing plate 24 is located near the upper part of the middle section of the mixed-gas combustion chamber 20. The middle part of the mixing plate 24 has a through hole. The top end of the delivery pipe 22 is connected to the through hole of the mixing plate 24. A second igniter 25 is installed in the mixed-gas combustion chamber 20, and the ignition head of the second igniter 25 is located above the through hole. A delivery pipe 22 is provided between the mixing plate 24 and the partition plate. The delivery pipe 22 is used to lead the gas in the preheating decomposition combustion chamber 10 to a position near the upper end of the mixed-gas combustion chamber 20. A flame arrester 221 is provided inside the delivery pipe 22 near the lower end.

[0040] An air pipe 23 is also provided on the outer peripheral wall of the mixed-gas combustion chamber 20. The function of the air pipe 23 is to introduce outside air into the air delivery cavity 21 of the mixed-gas combustion chamber 20. The air pipe 23 is located below the mixing plate 24. A second igniter 25 is provided above the mixing plate 24 and near the mixing plate 24. The second igniter 25 is used to ignite the mixed gas output from the delivery pipe 22. At the uppermost end of the mixed-gas combustion chamber 20 is the flame port 26, which is a narrowing section.

[0041] like Figure 2 As shown, an inverted cup-shaped air supply cap 241 is provided at the corresponding through hole of the mixing plate 24. The top surface of the air supply cap 241 has several first air supply holes 242, and the outer peripheral wall of the air supply cap 241 has several second air supply holes 243. Several vertically penetrating inner inclined holes 244 are provided inside the mixing plate 24, and the inner inclined holes 244 are distributed in a ring array with the axis of the mixing plate 24 as the center.

[0042] Combination Figure 3 As shown, the outer peripheral surface of the mixing disc 24 has several vertically penetrating external grooves, and the external grooves and the inner wall of the mixing combustion chamber 20 form an external hole 245, and the external hole 245 is distributed in a ring array with the axis of the mixing disc 24 as the center.

[0043] To ensure effective and stable combustion of the hydrogen-oxygen mixture within the preheating decomposition combustion chamber 10, the diameter of the burner nozzle 121 must be precisely calculated. The molar ratio of the hydrogen-oxygen mixture produced by water electrolysis is H2:O2 = 2:1, and the flame propagation velocity of the hydrogen-oxygen mixture is approximately 2.0-2.5 m / s. Based on the burner specifications and the hydrogen requirements due to ammonia decomposition rate, the diameter of the burner nozzle 121 needs to be optimized according to the outlet velocity of the hydrogen-oxygen mixture, the ammonia flow rate, and the pressure within the preheating decomposition combustion chamber 10. The outlet velocity of the hydrogen-oxygen mixture must be greater than its flame propagation velocity but less than the blow-out limit of the hydrogen flame to ensure stable combustion. The ammonia flow rate within the preheating decomposition combustion chamber 10 affects the pressure within the chamber and the impact of airflow disturbances on flame combustion stability; therefore, the diameter of the burner nozzle 121 should be as large as possible while ensuring stable combustion of the hydrogen-oxygen mixture.

[0044] Because hydrogen-oxygen mixtures are prone to flashback at high temperatures, a flashback prevention device must be incorporated into the design. This burner achieves two-stage flashback protection by incorporating a flashback arrestor and a flashback prevention device to ensure the safe and stable operation of the burner. The first-stage flashback protection uses a stainless steel powder die-casting material baffle between the mixing plate 24 and the burner nozzle 121. The baffle is manufactured using stainless steel powder die-casting technology to achieve primary flashback protection. The second-stage flashback protection uses a medium-pressure (0.01~10MPa) FA series-316L stainless steel flame arrestor core 221, installed in the gas path of the delivery pipeline 22 near the hydrogen-oxygen combustion gun side, to prevent flashback from entering the hydrogen-oxygen generator along the gas path and causing an explosion if the hydrogen-oxygen combustion gun's flameout prevention fails.

[0045] To achieve the decoupling reaction between hydrogen radicals and ammonia, a reaction zone is set above the Brownian tube 12. The reaction zone has a cylindrical cavity design, with the burner nozzle 121 of the oxyhydrogen combustion gun located at the lower center of the cylindrical cavity. To ensure sufficient contact between ammonia and the flame, ammonia is introduced horizontally from four ammonia pipes 13 on the side of the cylinder, and these inlets are located below the burner nozzle 121. The length of the cylindrical cavity needs to be rationally designed according to the height of the oxyhydrogen flame to avoid damage caused by the hydrogen flame directly burning the inner wall due to an excessively short cavity. Simultaneously, the fluid flow effect during burner operation must be considered to ensure that the high-speed jet of hydrogen flame can effectively entrain ammonia, thereby improving the mixing efficiency of ammonia and hydrogen radicals.

[0046] The length design of the preheating decomposition combustion chamber 10 needs to be fully considered to avoid excessive temperature drop, which would reduce the combustion efficiency of the high-temperature mixture. The mixing disc 24 at the high-temperature mixture outlet... Figure 2 As shown in Figure 2, a sleeve structure is adopted, in which the inner tube is used to flow the high-temperature mixed gas, while the outer tube is used to flow the air required for combustion, so as to realize the swirling flame and improve the combustion efficiency.

[0047] The ignition process of the burner is divided into two stages: ignition of the hydrogen-oxygen mixture and ignition of the products after ammonia decomposition. In the sealed combustion chamber 20, the combustion of the hydrogen-oxygen mixture requires ensuring its concentration is below the explosive limit of hydrogen (4.0%–75.6%) before ignition. To this end, air of a corresponding flow rate is introduced into the cylindrical cavity to dilute the hydrogen-oxygen mixture until successful ignition. After successful ignition, the entire burner is preheated using an electric spark from the first igniter 14, raising the internal temperature of the decomposition combustion chamber 10 to above 100°C to ensure complete fuel vaporization and rapid ignition. This mechanism effectively prevents ignition difficulties or unstable combustion problems that may occur during low-temperature startup. Ammonia is gradually introduced, and the combustion of the hydrogen-oxygen mixture flame is observed through a viewing window. If the flame goes out, the gas supply is immediately stopped. Once the required ammonia flow rate is reached, the high-temperature mixture is ignited again using an electric spark generated by the first igniter 14.

[0048] The first igniter 14 and the second igniter 25 employ high-voltage electronic ignition devices, capable of rapidly generating a strong electric arc to ensure rapid ignition of the hydrogen-oxygen mixture flame during the start-up phase. This system has an adaptive function, automatically adjusting ignition parameters according to the gas state within the burner, thereby improving ignition success rate and efficiency.

[0049] The four key technologies of the hydrogen-based ammonia reburner are all designed to improve combustion efficiency and ensure combustion process stability. Through meticulous design of the hydrogen-oxygen mixture combustion gun, optimization of the reaction zone structure, improvement of the burner nozzle design, and refinement of the ignition and stable combustion mechanism, the burner achieves high-efficiency and stable combustion. An integrated intelligent combustion control system monitors the internal temperature, pressure, and gas flow rate of the burner in real time. The system can automatically adjust fuel flow and air supply to maintain a stable combustion state. Through closed-loop control feedback, the system can promptly correct fluctuations in the combustion process, ensuring stability and high efficiency under various operating conditions.

[0050] The aforementioned hydrogen-based ammonia decomposition reburner is used to realize the hydrogen-based ammonia decomposition reburning method, which includes: introducing Brown gas into a closed space and igniting the Brown gas; introducing ammonia gas during the Brown gas ignition process; heating and activating the ammonia gas during the Brown gas combustion process; extracting the products after Brown gas combustion and the products after ammonia decomposition and adding combustion-supporting gas; and igniting the above-mentioned mixed gas to achieve the effect of ammonia decomposition and combustion.

[0051] The chemical reaction involving the combustion of ammonia and hydrogen is a chain reaction, which involves chain activation, propagation, and termination. Chain activation requires external factors (thermal energy, high-energy molecular collisions). Due to its high dissociation energy (NH bond dissociation energy is approximately 391 kJ / mol), ammonia combustion often faces problems of low combustion efficiency and high ignition energy. Hydrogen (H2), as a highly efficient fuel, produces a series of reactive free radicals during combustion. These free radicals are highly reactive, and the free radicals generated during hydrogen combustion (H radicals, OH radicals, etc.) can effectively participate in the chain reaction of ammonia combustion as high-energy molecules. Free radicals are atoms or molecules with unpaired electrons, making them highly reactive in chemical reactions. The introduction of these chain reaction mechanisms not only reduces the dissociation strength of the NH bond in the NH3 molecule, thus lowering the activation energy of ammonia decomposition, but also accelerates the conversion of ammonia into nitrogen and hydrogen.

[0052] The active free radicals and significant heat generated by hydrogen combustion are used to heat other parts of the burner and sustain the continuous decomposition of ammonia. The heat generated by hydrogen combustion not only drives the entire reaction chain but also provides the energy output required by the system. In the hydrogen-ammonia burner, the exothermic combustion process of hydrogen combines to form a closed thermal cycle. The heat released by hydrogen combustion compensates for the energy required for ammonia decomposition, while providing additional heat for equipment operation and energy output. In this way, the hydrogen-ammonia burner can efficiently convert ammonia and hydrogen into heat and energy, achieving a highly efficient combustion process and reducing NOx emissions.

[0053] The above content is only a preferred embodiment of the present invention. For those skilled in the art, many changes can be made in the specific implementation and application scope based on the ideas of the present invention. As long as these changes do not depart from the concept of the present invention, they all fall within the protection scope of this patent.

Claims

1. A hydrogen-based ammonia decomposition reburner, comprising: A preheating decomposition combustion chamber, wherein the interior of the preheating decomposition combustion chamber has a cavity, and the preheating decomposition combustion chamber is a vertical tubular body and is sealed at both the upper and lower ends by a flange structure; A Brownian tube passes through the wall of the preheating decomposition combustion chamber and its output end is located inside the cavity. The Brownian tube is installed at the lower end of the preheating decomposition combustion chamber, and a burner is provided at the output end of the Brownian tube. The first igniter passes through the wall of the preheating decomposition combustion chamber, and the ignition head of the first igniter is close to the burner nozzle at the output end of the Brownian tube. An ammonia gas pipe, the output end of which is connected to the interior of the cavity, and the position of the ammonia gas pipe is lower than the burner nozzle; The conveying pipeline has its input end connected to the inner cavity of the preheating decomposition combustion chamber. The input end of the conveying pipeline is connected to the upper end of the preheating decomposition combustion chamber. A flame arrestor is provided inside the conveying pipeline near the lower end. The second igniter has its ignition head near the output end of the delivery pipeline. The top of the preheating decomposition combustion chamber is connected to a tubular mixed-gas combustion chamber via a flange structure. A partition is provided between the upper end of the preheating decomposition combustion chamber and the lower end of the mixed-gas combustion chamber. This partition is used to divide the interior of the mixed-gas combustion chamber and the preheating decomposition combustion chamber into two independent cavities. A mixing plate is located near the upper part of the middle of the mixed-gas combustion chamber. The middle part of the mixing plate has a through hole. The top end of the delivery pipeline is connected to the through hole of the mixing plate. The second igniter is installed in the mixed-gas combustion chamber, and the ignition head of the second igniter is located above the through hole. The uppermost end of the mixed-gas combustion chamber is the flame port, which is a narrowing section.

2. The hydrogen-based ammonia decomposition reburner according to claim 1, characterized in that: There are multiple ammonia pipes, with the output end of the ammonia pipe facing the Brownian gas pipe. The ammonia pipes are arranged in a ring array in the preheating decomposition combustion chamber, and the ammonia pipes are located below the output end of the Brownian gas pipe.

3. The hydrogen-based ammonia decomposition reburner according to claim 1, characterized in that: The delivery pipeline has a flame-retardant core inside.

4. The hydrogen-based ammonia decomposition reburner according to claim 1, characterized in that: The air-fuel combustion chamber also includes an air pipe, which is connected to the interior of the air-fuel combustion chamber and is located below the mixing disc.

5. The hydrogen-based ammonia decomposition reburner according to claim 1, characterized in that: The mixing disc is provided with an inverted cup-shaped gas supply cap at the corresponding through hole. The top surface of the gas supply cap has several first gas supply holes, and the outer peripheral wall of the gas supply cap has several second gas supply holes.

6. The hydrogen-based ammonia decomposition reburner according to claim 1, characterized in that: The mixing disc has several vertically penetrating internal inclined holes, which are arranged in a ring array around the axis of the mixing disc.

7. The hydrogen-based ammonia decomposition reburner according to claim 1, characterized in that: The outer peripheral surface of the mixing disc has several vertically penetrating external grooves, and the external grooves and the inner wall of the mixing combustion chamber form an external hole, and the external hole is distributed in a ring array with the axis of the mixing disc as the center.

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