An integrated ammonia cracking and mixing combustion device and method

Abstract

This invention discloses an integrated ammonia cracking and hybrid combustion boiler. The boiler includes a furnace; a high-pressure injector is located in the lower part of the furnace, used to achieve MILD combustion within the furnace; an annular filled porous media regenerative catalytic device is located in the lower part of the furnace. This annular filled porous media regenerative catalytic device is an upright hollow frustum structure or an upright hollow truncated pyramid structure, filled with a heat storage medium and an ammonia cracking catalyst, and its surface is covered with a metal fiber mesh. This invention achieves simple and efficient ammonia cracking by embedding a heat storage medium within the furnace and filling it with an ammonia cracking catalyst, and extracting heat through high-temperature flue gas reflux, thus simplifying the cracking process and equipment used for ammonia combustion.

Description

Technical Field

[0001] This invention belongs to the field of thermal energy engineering technology, specifically relating to an integrated ammonia cracking and mixing combustion device and method. Background Technology

[0002] Global warming, caused by the greenhouse effect due to excessive emissions of greenhouse gases, has become a common environmental challenge facing all of humanity. In the short term, various CCUS technologies still face many problems such as high operating costs and limited technological maturity. Therefore, promoting new clean energy sources to replace traditional fossil fuels has become an important direction for the development of emission reduction and carbon reduction technologies.

[0003] In recent years, with the continuous improvement of clean and green hydrogen production technologies, combined with the excellent characteristics of hydrogen energy itself—high calorific value and low emissions—the promotion of hydrogen energy has seen a surge in popularity, and replacing fossil fuels with hydrogen energy seems to be a viable development direction for emission reduction and carbon reduction. However, in practical applications, the widespread use of hydrogen energy faces significant obstacles due to its characteristics such as high storage and transportation costs, significant risk of escape and leakage, extremely wide explosion limits, and combustion light spectrum bands that are outside the observation range.

[0004] Against this backdrop, ammonia energy has gradually come into focus. As a carbon-free fuel, ammonia, compared to hydrogen, can be liquefied at -33℃ or at 7-8 atmospheres of pressure at room temperature. Therefore, ammonia storage and transportation are very convenient, and a mature ammonia transportation network exists. Furthermore, ammonia fuel has a high volumetric energy density; even in its liquid state, the volumetric energy density of liquid ammonia is 1.5 times that of liquid hydrogen. In addition, ammonia is relatively safe to use. Firstly, its pungent odor allows for immediate detection in case of ammonia escape; secondly, ammonia has a narrow explosive limit, reducing the likelihood of explosions. Therefore, ammonia energy, as a 2.0 version of hydrogen energy, has enormous application potential.

[0005] However, in practical applications, the low calorific value and high ignition energy of ammonia make it difficult to achieve efficient and stable combustion using ammonia as a single fuel. Therefore, blending ammonia with a small amount of hydrogen is a better solution to improve fuel combustion stability and reduce ignition difficulty. For example, patent CN112984508B discloses a low-NOx swirl burner using hydrogen to inject ammonia. This low-NOx swirl burner includes a wind shield containing a coaxial primary swirl burner and a secondary burner. The primary swirl burner is located at the center and uses ammonia with a low hydrogen ratio as fuel. The secondary burner is located around the primary burner and uses ammonia mixed with hydrogen as fuel. The center of the primary swirl burner is a primary hydrogen fuel nozzle, surrounded by several ammonia fuel nozzles. Swirl blades are arranged around the periphery of the primary fuel nozzle. This invention uses ammonia as the main fuel with low-NOx hydrogen blending, which makes the flame more stable and reduces nitrogen oxide emissions. However, this invention increases the initial fuel's dependence on hydrogen by mixing ammonia with hydrogen, and cannot solve the problems caused by hydrogen storage and transportation.

[0006] Patent CN210656142U discloses an auxiliary ammonia combustion pyrolysis hydrogen production device capable of achieving ammonia-hydrogen co-combustion. The auxiliary ammonia combustion pyrolysis hydrogen production device includes a combustion chamber, within which a tube bundle cross-flow heat exchanger and an ammonia burner are installed. The burner is connected to the inlet of the combustion chamber, and the tube bundle cross-flow heat exchanger houses an ammonia cracking device. The outlet of the cracked mixed gas is connected to the burner. This invention utilizes ammonia combustion to heat the tube bundle cross-flow heat exchanger, and the hydrogen-nitrogen mixture produced after ammonia pyrolysis serves as the combustion-supporting gas for ammonia, achieving continuous and stable ammonia combustion. While this device eliminates the need for hydrogen from the original fuel, it requires a separate ammonia cracking device and a gas return pipeline within the furnace, increasing the complexity and hazard of the device. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide an integrated ammonia cracking and mixing combustion device and method.

[0008] According to a first aspect of the present invention, an integrated ammonia cracking and hybrid combustion boiler is provided.

[0009] An integrated ammonia cracking and mixed combustion boiler includes a furnace; a high-pressure injector is provided at the lower part of the furnace for achieving MILD combustion within the furnace; a flue gas exhaust device is provided at the upper part of the furnace; a coil heat exchanger is provided at the upper part of the furnace; and an annular filled porous media regenerative catalytic device is provided at the lower part of the furnace. The annular filled porous media regenerative catalytic device has an upright frustum structure, and its interior is filled with a mixture of heat storage material and ammonia cracking catalyst. The surface of the annular filled porous media regenerative catalytic device is wrapped with a metal fiber mesh.

[0010] Furthermore, the porous media regenerative catalytic device is a hollow frustum shape, with the hollow area along the axis serving as a hollow channel. This hollow channel can be a cylindrical channel or a tapering frustum-shaped channel. The high-speed mixed gas flow ejected from the bottom injector of the furnace enters the furnace through the bottom inlet of the channel. The ratio of the outer diameter to the inner diameter of the bottom surface of the annular porous media regenerative catalytic device is preferably 2 to 3.5. The angle between the outer inclined surface of the annular porous media regenerative catalytic device and the inner wall of the furnace is preferably 45 to 60°. Due to the entrainment effect of the high-speed mixed gas flow, the flue gas and ammonia injected from the side stream of the furnace will pass through the side wall of the annular porous media regenerative catalytic device and fully mix with the high-speed mixed gas flow ejected from the injector, then be ejected upwards and rapidly diffused throughout the entire furnace space, forming MILD combustion.

[0011] Furthermore, the ammonia cracking catalyst is preferably a nickel-based catalyst with a high operating temperature range (generally 850~1000℃).

[0012] According to a second aspect of the present invention, the present invention provides an integrated ammonia cracking and mixing combustion device, including the integrated ammonia cracking and mixing combustion boiler described above.

[0013] Specifically, the integrated ammonia cracking and mixing combustion equipment of the present invention includes: an integrated ammonia cracking and mixing combustion boiler, a liquid ammonia pipeline, an air pipeline, a natural gas pipeline, a gas heat exchanger, and a gas distribution system; wherein, the gas distribution system includes thermocouples, a DCS controller, flow controller I, flow controller II, and a gas mixer; the thermocouples are located near the porous media regenerative catalytic device inside the boiler and are used to monitor the operating status of the combustion boiler and the ambient temperature of the porous media regenerative catalytic device; the DCS controller is used to receive the detection signals from the thermocouples and to dynamically adjust the gas distribution system (issuing operating commands to flow controller I and flow controller II); flow controller I is used to adjust the flow rate of ammonia entering the porous media regenerative catalytic device, and flow controller II is used to control the flow rate of ammonia entering the high-pressure gas injector.

[0014] Furthermore, the liquid ammonia pipeline is connected to the inlets of flow controller I and flow controller II respectively after passing through a vaporization heat exchanger. The outlet of flow controller I is connected to a porous medium heat storage device through several ammonia side lines, and the outlet of flow controller II is connected to the inlet of a gas mixer.

[0015] Furthermore, the flue gas exhaust equipment of the combustion boiler is connected to the gas heat exchanger and the atmosphere via pipelines.

[0016] Furthermore, the system also includes a natural gas flow controller, which is used to control the flow of natural gas entering the high-pressure injector during the initial startup of the combustion system.

[0017] Furthermore, the air pipeline is connected to the inlet of the gas mixer via a fan.

[0018] Furthermore, the gas distribution system can dynamically adjust the fuel supply to the combustion system according to the operating status of the combustion system.

[0019] Furthermore, based on the characteristics of ammonia-hydrogen co-combustion and the actual temperature required for ammonia cracking by the catalyst in the porous media regenerative catalytic device, the operating temperature of the thermocouple is generally between 800 and 1200°C. Conventional thermocouples in this field can be selected, preferably type S or type B platinum-rhodium thermocouples, fitted with a No. 99 corundum sheath.

[0020] Furthermore, the input terminal of the DCS controller is connected to a thermocouple to collect temperature data measured by the thermocouple, while the output terminal of the DCS controller is connected to flow controller I and flow controller II respectively, and the flow rate of the two flow controllers is adjusted by detecting the temperature inside the furnace.

[0021] Furthermore, upstream of flow controller I and flow controller II is a liquid ammonia pipeline. Liquid ammonia is heated by a vaporization heat exchanger to form ammonia gas, which is then introduced into flow controller I and flow controller II.

[0022] Furthermore, the downstream branch of the flow controller I consists of 2 to 8 side lines, each of which is connected to the porous medium thermal regenerative catalytic device.

[0023] Furthermore, the flow controller II is connected to the side line of the gas mixer, with a valve (needle valve) installed between them. The left inlet of the gas mixer is connected to the blower, and the outlet of the gas mixer is connected to the inlet of the high-pressure injector.

[0024] According to a third aspect of the present invention, the present invention also provides an integrated ammonia cracking and mixing combustion method, wherein the above-described integrated ammonia cracking and mixing combustion equipment is used.

[0025] Specifically, the integrated ammonia cracking and combustion method includes the following:

[0026] (1) The combustion system is started and enters the preheating stage, during which natural gas is used as fuel; combustion air and natural gas are injected into the furnace through a high-pressure injector and the furnace is preheated by MILD combustion.

[0027] (2) When the temperature inside the furnace reaches the preheating requirement, stop the supply of natural gas to the high-pressure injector and switch to ammonia fuel combustion mode;

[0028] (3) Ammonia gas from the sidewall of the furnace is introduced into a porous medium regenerative catalytic device. Under the action of high temperature and catalyst, most of the ammonia gas is decomposed into nitrogen and hydrogen.

[0029] (4) Another stream of ammonia gas is introduced into the gas mixer and fully mixed with the combustion air before being injected into the high-pressure injector; the ammonia and air mixture is injected into the furnace by the high-pressure injector, and the high-speed gas jet will form a Venturi effect at the lower end of the furnace and draw out the mixture of cracked nitrogen and hydrogen through the inside of the metal fiber mesh and inject it into the furnace for combustion.

[0030] (5) When the mixed gas leaves the downstream outlet of the porous media heat storage catalytic device, the rapid expansion of the space will form a reflux zone at the upper end of the porous media heat storage catalytic device, so that some of the high-temperature flue gas formed by the combustion of the mixed gas will flow back and be injected into the porous media heat storage catalytic device through the metal fiber mesh from the outside, so as to achieve continuous heating of it.

[0031] (6) The remaining high-temperature flue gas is discharged by the exhaust device. Part of the high-temperature flue gas is injected into the gasification heat exchanger to exchange heat with liquid ammonia to prepare the ammonia required for combustion. The remaining flue gas is discharged after treatment.

[0032] Furthermore, the process conditions or other details that need to be added can be described in more detail.

[0033] Furthermore, in step (1), in order to achieve the MILD combustion effect, the high-pressure injector injection speed is not less than 90m / s.

[0034] Furthermore, in step (5), after the mixed gas leaves the downstream outlet of the porous media regenerative catalytic device, the rapid expansion of the space will form a reflux zone at the upper end of the porous media regenerative catalytic device, so that some of the high-temperature flue gas formed by the combustion of the mixed gas will flow back and enter the porous media regenerative catalytic device through the metal fiber mesh from the outside, thereby achieving continuous heating and maintaining the activity of the ammonia cracking catalyst in the porous media regenerative catalytic device.

[0035] Compared with the prior art, the integrated ammonia cracking and mixing combustion equipment and method of the present invention have the following advantages:

[0036] 1. In the integrated ammonia cracking and mixing combustion equipment of the present invention, a simple and efficient cracking of ammonia is achieved by using a built-in heat storage catalytic device in the furnace and filling it with an ammonia cracking catalyst, and taking heat by high-temperature flue gas reflux. Furthermore, the filled porous medium heat storage device and the ammonia cracking catalyst are easy to replace and maintain, simplifying the cracking process and equipment used for ammonia combustion.

[0037] 2. In the integrated ammonia cracking and mixing combustion equipment of the present invention, premixed gas is injected into the furnace by a high-pressure injector and the cracked gas cracked by the porous medium heat storage catalytic device on the side wall is entrained. The entire process of cracking, entrainment, mixing and combustion is realized inside the furnace, which not only improves the mixing and combustion effect of the mixed gas, but also greatly simplifies the design requirements of the burner.

[0038] 3. In the integrated ammonia cracking and mixing combustion equipment and method of the present invention, the combustion process has the characteristics of being safe and reliable, simple equipment and operation, low operating cost, and significant energy saving effect. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the furnace structure in the integrated ammonia cracking and mixing combustion equipment of the present invention.

[0040] Figure 2 This is a schematic diagram of the integrated ammonia cracking and mixing combustion equipment of the present invention.

[0041] Figure 3 This is a schematic diagram of section AA.

[0042] In the diagram, the corresponding component names are as follows: 1-furnace, 2-high-pressure injector, 3-exhaust equipment, 100-porous medium thermal regenerative catalytic device, 101-coil heat exchanger, 102-thermal regenerative filling material, 103-metal fiber mesh, 4-liquid ammonia pipeline, 5-air pipeline, 6-natural gas pipeline, 7-gasification heat exchanger, 8-gas distribution system, 801-thermocouple, 802-DCS controller, 803-flow controller I, 804-flow controller II, 805-gas mixer, 806-ammonia side line, 807-valve, 9-natural gas flow controller, 10-fan. Detailed Implementation

[0043] The technical solution of the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments.

[0044] Example 1

[0045] like Figure 1 As shown, the present invention provides an integrated ammonia cracking and mixed combustion boiler, including a furnace 1; a high-pressure injector 2 is provided in the lower part of the furnace; a flue gas exhaust device 3 is provided in the upper part of the furnace; a coil heat exchanger 101 is provided in the upper part of the furnace; and a porous media heat storage catalytic device 100 is provided in the lower part of the furnace. The porous media heat storage catalytic device is an upright hollow frustum structure or an upright truncated pyramid structure. The heat storage filling material 102 in the porous media heat storage catalytic device is a heat storage body and an ammonia cracking catalyst. The heat storage filling material 102 is covered with a metal fiber mesh 103.

[0046] The porous media regenerative catalytic device 100 is in the shape of a hollow frustum, and the ratio of its outer diameter to its inner diameter is preferably 2 to 3.5. The angle between the outer inclined surface of the porous media regenerative catalytic device 100 and the inner wall of the furnace is preferably 45 to 60°.

[0047] Example 2

[0048] like Figure 2As shown, the present invention also provides an integrated ammonia cracking and mixing combustion device, including the aforementioned integrated ammonia cracking and mixing combustion boiler, a liquid ammonia pipeline 4, an air pipeline 5, a natural gas pipeline 6, a gasification heat exchanger 7, and a gas distribution system 8; wherein, the gas distribution system 8 includes a thermocouple 801, a DCS controller 802, a flow controller I 803, a flow controller II 804, and a gas mixer 805; the thermocouple 801 is located near the porous media heat storage catalytic device 100 inside the boiler and is used to monitor the operating status of the combustion boiler and the ambient temperature of the porous media heat storage catalytic device 100; the DCS controller 802 is used to receive the detection signal from the thermocouple 801 and to dynamically adjust the gas distribution system (issuing operation commands to the flow controller I 803 and the flow controller II 804); the flow controller I 803 is used to adjust the flow rate of ammonia entering the porous media heat storage catalytic device, and the flow controller II 804 is used to control the flow rate of ammonia entering the high-pressure gas injector 2. The liquid ammonia pipeline 4 is connected to the inlets of flow controller I 803 and flow controller II 804 via the gasification heat exchanger 7. The outlet of flow controller I 803 is connected to the porous media heat storage catalytic device 100 via several ammonia side lines 806, and the outlet of flow controller II 804 is connected to the inlet of the gas mixer 805. The flue gas equipment 3 of the combustion boiler is connected to the gas heat exchanger 7 and the atmosphere via pipelines. The system also includes a natural gas flow controller 9, which is used to control the flow rate of natural gas entering the high-pressure injector 2 during the initial startup of the combustion system. The air pipeline 5 is connected to the inlet of the gas mixer 805 via the fan 10.

[0049] Furthermore, the gas distribution system 8 can dynamically adjust the fuel supply to the combustion system according to the operating status of the combustion system.

[0050] Furthermore, based on the characteristics of ammonia-hydrogen co-combustion and the actual temperature required for ammonia cracking by the catalyst in the porous media regenerative catalytic device 100, the operating temperature of thermocouple 801 is basically between 800 and 1200°C. Thermocouple 801 can be a conventional thermocouple in the art, preferably a type S or type B platinum-rhodium thermocouple, fitted with a No. 99 corundum sheath.

[0051] Furthermore, the input terminal of the DCS controller 802 is connected to the thermocouple 801 to collect the temperature data measured by the thermocouple 801, while the output terminal of the DCS controller 802 is connected to the flow controller I 803 and the flow controller II 804 respectively, and the flow rate of the two flow controllers is adjusted by detecting the temperature inside the furnace 1.

[0052] Furthermore, upstream of the flow controller I 803 and flow controller II 804 is a liquid ammonia pipeline 4. The liquid ammonia is heated by the vaporization heat exchanger 7 to form ammonia gas, which is then introduced into the flow controller I 803 and flow controller II 804.

[0053] Furthermore, the downstream branch of the flow controller I 803 consists of 2 to 8 ammonia side lines 806, each of which is connected to the porous medium heat storage catalytic device 100.

[0054] Furthermore, the flow controller II 804 is connected to the side of the gas mixer 805, with a valve 807 (needle valve) installed between them. The left inlet of the gas mixer 805 is connected to the blower 10, and the outlet of the gas mixer 805 is connected to the inlet of the high-pressure injector 2.

[0055] Example 3

[0056] Combination Figure 1-3 The working process of the integrated ammonia cracking and mixing combustion equipment of the present invention is as follows:

[0057] (1) The combustion system is started and enters the preheating stage. Natural gas is used as fuel in this stage. Combustion air and natural gas are injected into the furnace 1 through the high-pressure injector 2 and preheat the furnace 1 by MILD combustion. The injection speed of the high-pressure injector 2 is not less than 90m / s.

[0058] (2) When the temperature inside the furnace 1 reaches the preheating requirement, the supply of natural gas to the high-pressure injector 2 is stopped, and the combustion mode of ammonia fuel is switched.

[0059] (3) Multiple streams of ammonia gas are introduced into the porous medium heat storage catalytic device 100. Under the action of high temperature and catalyst, most of the ammonia gas is decomposed into nitrogen and hydrogen.

[0060] (4) Another stream of ammonia gas is introduced into the gas mixer 805 and fully mixed with the combustion air before being injected into the high-pressure injector 2; the ammonia and air mixture is injected into the furnace 1 by the high-pressure injector, and the high-speed gas jet will form a Venturi effect at the lower end of the furnace 1 and draw out the mixture of cracked nitrogen and hydrogen through the inside of the metal fiber mesh 103 and inject it into the furnace 1 for combustion.

[0061] (5) When the mixed gas leaves the outlet at the upper end of the porous media heat storage catalytic device 100, due to the rapid expansion of the space, a reflux zone will be formed at the upper end of the porous media heat storage catalytic device 100, so that part of the high-temperature flue gas formed by the combustion of the mixed gas will flow back and be injected into the porous media heat storage catalytic device 100 through the metal fiber mesh 103 from the outside, thereby achieving continuous heating of the heat storage body.

[0062] (6) The remaining high-temperature flue gas is discharged by the exhaust device 3. Part of the high-temperature flue gas is injected into the gasification heat exchanger 7 to exchange heat with liquid ammonia to prepare the ammonia required for combustion. The remaining flue gas is discharged after treatment.

[0063] In step (5), after the mixed gas leaves the outlet at the upper end of the porous media heat storage catalytic device 100, the rapid expansion of the space will form a reflux zone at the upper end of the porous media heat storage catalytic device 100, so that some of the high-temperature flue gas formed by the combustion of the mixed gas will flow back and enter the porous media heat storage catalytic device 100 through the metal fiber mesh 103 from the outside, thereby achieving continuous heating of the heat storage filling material 102 and maintaining the activity of the ammonia cracking catalyst in the porous media heat storage catalytic device 100.

[0064] Example 4

[0065] use Figure 3 The combustion system described above, boiler 1 adopts as follows: Figure 1 The structure described above was simulated using ANSYS-FLUENT software under the following operating conditions: The furnace combustion power is 50kW; the porous media regenerative catalytic converter has an inner diameter of 200mm, a bottom outer diameter of 600mm, and a height of 200mm; the angle between the outer inclined surface of the porous media regenerative catalytic converter 100 and the inner wall of the furnace is 45°. The regenerative filling material 102 inside the porous media regenerative catalytic converter 100 consists of ceramic regenerative spheres with a diameter of 5-10mm, and nickel-based ammonia cracking catalyst is filled in the gaps. During the equipment startup phase, valve 807 is closed, and the natural gas flow controller 9 is turned on, with a flow rate of 5Nm³ / h. 3 Natural gas is introduced at a flow rate of / h. During the preheating stage, the combustion equivalence ratio φ is set to 0.84. The mixture of natural gas and air is injected by high-pressure injector 2 at a speed of 150 m / s, preheating the furnace in the form of MILD combustion. When the temperature of thermocouple 801 reaches 1000℃, the natural gas flow controller 9 is closed and valve 807 is opened, initiating the switch to ammonia combustion mode. During the ammonia combustion stage, the equivalence ratio is set to 0.95, and the ammonia consumption is 12.5 Nm³. 3 / h, of which 40% of the ammonia is injected into the porous medium regenerative catalytic device 100 via the ammonia side stream 806 for cracking, and 60% of the ammonia is mixed with air and injected into the furnace at a speed of 200m / s by the high-pressure injector 2. At this time, the highest temperature in the furnace is close to 1000℃, and the high-temperature gas reflux rate is close to 20%, which can simultaneously meet the heat storage requirements of the regenerative filling material and the temperature requirements of the ammonia cracking catalyst, thus achieving stable combustion.

Claims

1. An integrated ammonia cracking and mixing combustion device, characterized in that, It includes an integrated ammonia cracking and mixed combustion boiler, liquid ammonia pipeline, air pipeline, natural gas pipeline, gasification heat exchanger, and gas distribution system; The integrated ammonia cracking and mixed combustion boiler includes a furnace; a high-pressure injector is provided at the lower part of the furnace, and the injector is used to achieve MILD combustion in the furnace; The upper part of the furnace is equipped with a flue gas exhaust device; the upper space inside the furnace is equipped with a coil heat exchanger; The lower part of the furnace is equipped with an annular filled porous media regenerative catalytic device. The annular filled porous media regenerative catalytic device is an upright hollow truncated cone structure or an upright hollow prism structure. The annular filled porous media regenerative catalytic device is filled with a heat storage body and an ammonia cracking catalyst. The surface of the annular filled porous media regenerative catalytic device is covered with a metal fiber mesh. The gas distribution system includes a thermocouple, a DCS controller, a flow controller I, a flow controller II, and a gas mixer; the liquid ammonia pipeline is connected to the inlets of flow controller I and flow controller II respectively after passing through a vaporization heat exchanger; the outlet of flow controller I is connected to a porous medium heat storage catalytic device through several ammonia side lines; and the outlet of flow controller II is connected to the inlet of the gas mixer. The thermocouple is located near the porous media thermal catalytic regeneration device inside the boiler and is used to monitor the operating status of the combustion boiler and the ambient temperature of the porous media thermal catalytic regeneration device. The DCS controller is used to receive the detection signal from the thermocouple and to dynamically adjust the gas distribution system. The flow controller I is used to adjust the flow rate of ammonia entering the porous media thermal catalytic regeneration device, and the flow controller II is used to control the flow rate of ammonia entering the high-pressure gas injector.

2. The ammonia cracking and mixing combustion device according to claim 1, characterized in that, The annular filled porous media thermal storage catalytic device is in the shape of a hollow frustum; the ratio of its outer diameter to its inner diameter is 2 to 3.

5.

3. The mixing combustion device according to claim 1, characterized in that, The angle between the outer inclined surface of the annular porous media regenerative catalytic device and the inner wall of the furnace is 45~60°.

4. The ammonia cracking and mixing combustion equipment according to claim 1, characterized in that, The ammonia cracking catalyst is a nickel-based catalyst.

5. The ammonia cracking and mixing combustion device according to claim 1, characterized in that, It also includes a natural gas flow controller, which is used to control the flow of natural gas into the high-pressure injector during the initial startup of the combustion system.

6. The ammonia cracking and mixing combustion device according to claim 1, characterized in that, The air line is connected to the inlet of the gas mixer via a fan.

7. The ammonia cracking and mixing combustion device according to claim 1, characterized in that, The gas distribution system dynamically adjusts the fuel supply to the combustion system according to the operating status of the combustion system.

8. The ammonia cracking and mixing combustion device according to claim 1, characterized in that, The input terminal of the DCS controller is connected to the thermocouple to collect temperature data measured by the thermocouple, while the output terminal of the DCS controller is connected to flow controller I and flow controller II respectively, and the flow rate of the two flow controllers is adjusted by detecting the temperature inside the furnace.

9. The ammonia cracking and mixing combustion device according to claim 1, characterized in that, The downstream branch of the flow controller I consists of 2 to 8 side lines, each of which is connected to the porous media thermal regenerative catalytic device.

10. The ammonia cracking and mixing combustion device according to claim 1, characterized in that, The flow controller II is connected to the side line of the gas mixer, and a valve is installed between them. The left inlet of the gas mixer is connected to the blower, and the outlet of the gas mixer is connected to the inlet of the high-pressure injector.

11. An integrated ammonia cracking and mixing combustion method, wherein the integrated ammonia cracking and mixing combustion device according to any one of claims 1-10 is used.

12. The mixing combustion method according to claim 11, characterized in that, Includes the following: (1) The combustion system is started and enters the preheating stage, during which natural gas is used as fuel; combustion air and natural gas are injected into the furnace through a high-pressure injector and the furnace is preheated by MILD combustion. (2) When the temperature inside the furnace reaches the preheating requirement, stop the supply of natural gas to the high-pressure injector and switch to ammonia fuel combustion mode; (3) The ammonia gas injected into the side wall is introduced into the porous medium regenerative catalytic device. Under the action of high temperature and catalyst, most of the ammonia gas is decomposed into nitrogen and hydrogen. (4) Another stream of ammonia gas is introduced into the gas mixer and fully mixed with the combustion air before being injected into the high-pressure injector; the ammonia and air mixture is injected into the furnace by the high-pressure injector, and the high-speed gas jet will form a Venturi effect at the lower end of the furnace and draw out the mixture of cracked nitrogen, hydrogen and uncracked ammonia gas through the inside of the metal fiber mesh and inject it into the furnace for combustion. (5) When the mixed gas leaves the downstream outlet of the porous media heat storage catalytic device, a reflux zone is formed at the upper end of the porous media heat storage catalytic device, so that part of the high-temperature flue gas formed by the combustion of the mixed gas flows back and is injected into the porous media heat storage catalytic device through the metal fiber mesh from the outside of the porous media heat storage catalytic device, so as to achieve continuous heating of it. (6) The remaining high-temperature flue gas is discharged by the exhaust device. Part of the high-temperature flue gas is injected into the gasification heat exchanger to exchange heat with liquid ammonia to prepare the ammonia required for combustion. The remaining flue gas is discharged after treatment.

13. The mixed combustion method according to claim 12, characterized in that, The high-pressure injector has a spray speed of not less than 90 m / s.

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