Micro ultralow-emission ammonia combustion device and method based on catalytic cracking and combustion

Abstract

The embodiment of the invention provides a miniature ultralow-emission ammonia combustion device based on catalytic cracking and combustion. The miniature ultralow-emission ammonia combustion device comprises a combustor, a fuel input unit, an air input unit, a turbine and a thermophotovoltaic unit. The combustor is a pre-cracking type ammonia combustor and internally comprises two cracking reaction micro-channels with the inner wall faces plated with ammonia cracking catalyst coatings and a combustion channel with the inner wall face plated with an ammonia combustion catalyst coating, ammonia gas is subjected to catalytic cracking in the cracking reaction micro-channels, generated mixed gas is subjected to catalytic combustion in the combustion channel, and the mixed gas is subjected to catalytic combustion in the combustion channel. Heat radiation and high-temperature tail gas are further utilized for power generation. The high-efficiency and low-pollution combustion of ammonia gas can be realized, energy generated by combustion is converted into mechanical energy and electric energy through the turbine and the thermophotovoltaic unit, and the combustion device is compact in design, stable in performance and simple and convenient to operate and has remarkable environmental benefits and economic benefits. The embodiment of the invention further provides a method using the device.

Description

Technical Field

[0001] The present invention belongs to the technical field of ammonia catalytic cracking and catalytic combustion, and particularly relates to a micro ultra-low emission ammonia combustion device based on catalytic cracking and combustion. The present invention also provides a micro ultra-low emission ammonia combustion method based on catalytic cracking and combustion using the device. Background Art

[0002] In recent years, alternative fuels and clean combustion technologies have gradually become an important development trend in reducing carbon emissions. As one of the world's most produced chemical products, ammonia has the significant advantage of zero carbon emissions in its combustion process. The higher octane number of ammonia can also effectively improve the engine's anti-knock performance. Compared with hydrogen, another carbon-free fuel, ammonia has significant advantages in storage and transportation. Currently, there are mature supporting facilities that can store and transport it safely and conveniently. However, while it has excellent properties, using ammonia as a fuel also faces some challenges, including narrow flammable boundaries, unstable combustion, high ignition temperatures, and long ignition delay times. In addition, the nitrogen element in ammonia easily combines with oxygen during combustion to release a large amount of nitrogen oxides NO. x , such as NO, NO 2 and N 2 O, will cause serious pollution to the environment.

[0003] Studies have shown that adding a small amount of hydrogen to ammonia can significantly improve its combustion performance and reduce NO x Emissions. In order to solve the difficulties encountered by ammonia during ignition and combustion, a reasonable idea is to partially crack ammonia to produce hydrogen, and then burn the ammonia-hydrogen mixture as fuel. The cracking process of ammonia has been studied for many years, and its reaction conditions are relatively mild. The use of catalysts can also significantly reduce the temperature of the cracking reaction and increase the conversion rate of ammonia. Among them, ruthenium (Ru) and platinum (Pt) catalysts, as commonly used ammonia cracking and ammonia combustion catalysts, can exhibit excellent performance at low temperatures and close to thermodynamic equilibrium conditions, and are considered to be one of the most ideal catalysts for ammonia cracking and combustion.

[0004] Since ammonia cracking to produce hydrogen is an endothermic reaction that requires a high temperature environment to maintain its occurrence, past research has mainly focused on how to achieve efficient cracking of ammonia. There are relatively few studies on the subsequent combustion process of the products of ammonia catalytic cracking, and there is a lack of self-sustaining burners designed based on this idea. Therefore, it is urgent to develop ammonia burners and related technologies that use ruthenium and platinum as catalysts to obtain hydrogen by pre-cracking ammonia, and can self-sustain clean combustion, so as to effectively improve the combustion performance of ammonia for fuel applications. Summary of the invention

[0005] The present invention aims to solve the problem that the prior art lacks an ammonia burner capable of self-sustaining clean combustion based on catalytic cracking and subsequent catalytic combustion of ammonia. A miniature ultra-low emission ammonia combustion device and method based on catalytic cracking and combustion are provided. Self-sustaining clean combustion of ammonia is achieved through catalytic pre-cracking of ammonia and subsequent catalytic combustion, so as to solve the problems of narrow flammable boundary of ammonia combustion itself, difficulty in ignition, unstable combustion and high nitrogen oxide emissions, thereby effectively improving the combustion performance of ammonia.

[0006] The technical solution is as follows:

[0007] The micro ultra-low emission ammonia combustion device based on catalytic cracking and combustion provided by an embodiment of the present invention comprises a burner, a fuel input unit and an air input unit, wherein:

[0008] The shell of the burner is divided into three reaction microchannels arranged adjacent to each other in sequence. The two reaction microchannels located on the outside are cracking reaction microchannels with ammonia cracking catalyst coatings coated on the inner wall surfaces, which are used for catalytic cracking reaction of ammonia; the middle reaction microchannel is a combustion channel with ammonia combustion catalyst coatings coated on the inner wall surface, which is used for catalytic combustion of mixed gas after ammonia cracking; one end of the three reaction microchannels is connected together, and the end is provided with an air inlet aimed at the combustion channel, and the air input unit is connected to the air inlet to input air; the other end of the cracking reaction microchannel that is not connected together is provided with an ammonia inlet, and the fuel input unit is connected to the ammonia inlet to input ammonia; the other end of the combustion channel that is not connected together is provided with an exhaust gas outlet for high-temperature exhaust gas to be discharged.

[0009] As a preferred fuel input unit, the fuel input unit includes an ammonia gas storage cylinder, and the ammonia gas storage cylinder is connected to the ammonia gas inlet to transport ammonia gas to the cracking reaction microchannel.

[0010] Preferably, the air input unit comprises a compressor, and the compressor is connected to the air inlet to supply compressed air to the combustion channel.

[0011] Preferably, the device further comprises a turbine, wherein the turbine is connected to the exhaust gas outlet and is driven by the high-temperature exhaust gas discharged from the combustion channel.

[0012] Preferably, the device further comprises a thermophotovoltaic unit, which is arranged outside the shell and generates electricity using heat energy conducted by the shell.

[0013] As a preferred embodiment of the above technical solution, the ammonia cracking catalyst coating may adopt an ammonia cracking catalyst such as ruthenium, nickel, iron or high entropy alloy, and is more preferably a ruthenium catalyst; the ammonia combustion catalyst coating may adopt an ammonia combustion catalyst such as platinum, palladium, rhodium, or cerium, and is more preferably a platinum catalyst.

[0014] In the above-mentioned connecting pipeline for conveying gas, valves can be set at various control parts of the pipeline, and corresponding valves can be configured for different pipe sections, such as various flow regulating valves or one-way valves, etc., which can be configured according to actual working conditions and will not be elaborated here.

[0015] The embodiment of the present invention further provides a method for a micro ultra-low emission ammonia combustion device based on the aforementioned catalytic cracking and combustion, comprising the following steps:

[0016] Step 1: Ammonia gas is introduced into the cracking reaction microchannel in the burner, and the ammonia gas is fully contacted with the ammonia cracking catalyst to cause a catalytic cracking reaction;

[0017] Step 2: passing air into the combustion channel from one end of the three reaction microchannels in the burner that are connected together;

[0018] Step 3: The mixed gas generated by the catalytic cracking of ammonia in the cracking reaction microchannel enters the combustion channel together with the air, fully contacts with the ammonia combustion catalyst, and a catalytic combustion reaction occurs;

[0019] Step 4: Expel the high-temperature exhaust gas obtained from combustion from the burner.

[0020] As a preferred embodiment of step 3, the heat generated by the catalytic combustion is conducted to a thermal photovoltaic power generation device to generate electricity.

[0021] As a preferred embodiment of step 4, the high-temperature exhaust gas discharged from the burner is used to drive the turbine.

[0022] Preferably, the ammonia cracking catalyst in step 1 is ruthenium, nickel, iron or a high entropy alloy, more preferably ruthenium; the ammonia combustion catalyst in step 3 is platinum, palladium, rhodium or cerium, more preferably platinum.

[0023] The above technical solution of the embodiment of the present invention conducts in-depth research on the combustion performance of ammonia cracking and its products under different working conditions, guides the design and optimization of related burners, respectively uses common catalysts such as ruthenium and platinum to catalyze the cracking and combustion of ammonia, and adopts a pre-cracking ammonia burner to achieve self-sustaining clean combustion of ammonia. Its beneficial effects are as follows:

[0024] 1. The use of catalytic cracking technology and catalytic combustion technology for the cracking and combustion of ammonia only requires two raw materials, ammonia and air, and no other raw materials are required. The device can achieve self-sustaining combustion without the need for additional energy input, and greatly reduces nitrogen oxide emissions. The design system is compact and simple, reducing its manufacturing and operating costs;

[0025] 2. It creates conditions for the full utilization of ammonia. The use of high-temperature tail gas for heat recovery can appropriately increase the temperature of the microchannel catalytic reactor, which is beneficial to improving the ammonia cracking rate. At the same time, it avoids the problems of narrow flammable boundary, difficult ignition, high nitrogen oxide emissions, etc. of direct combustion of ammonia;

[0026] 3. The burner shell wall conducts heat, which can be used for thermal photovoltaic power generation or thermoelectric power generation. The exhaust gas outlet of the burner can be connected to a small turbine to drive work, thereby achieving full utilization of energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The following drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the specific implementation, they are used to explain the present invention but do not constitute a limitation of the present invention. They include:

[0028] Figure 1 A schematic diagram of the structure of a micro ultra-low emission ammonia combustion device based on catalytic cracking and combustion provided in an embodiment of the present invention;

[0029] Figure 2 A schematic flow chart of the steps of a micro ultra-low emission ammonia combustion method based on catalytic cracking and combustion provided in an embodiment of the present invention.

[0030] [Description of main component symbols]

[0031] 1-burner; 11-shell;

[0032] 12-cracking reaction microchannel; 121-ammonia cracking catalyst coating; 122-ammonia gas inlet;

[0033] 13-combustion channel; 131-ammonia combustion catalyst coating; 132-air inlet; 133-exhaust gas outlet;

[0034] 2- ammonia gas cylinder; 3- compressor; 4- turbine; 5- thermophotovoltaic unit. DETAILED DESCRIPTION

[0035] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0036] In view of the existing problems, the present invention provides a micro ultra-low emission ammonia combustion device and method based on catalytic cracking and combustion, aiming to utilize ammonia as fuel in an efficient and environmentally friendly manner to achieve a low-pollution and high-efficiency combustion process.

[0037] In order to realize the above technical solution, Figure 1 As shown, an embodiment of the present invention provides a micro ultra-low emission ammonia combustion device based on catalytic cracking and combustion, comprising a burner 1, an ammonia gas cylinder 2, a compressor 3, a turbine 4 and a thermophotovoltaic unit 5, wherein:

[0038] The shell 11 of the burner 1 is divided into three reaction microchannels arranged adjacent to each other in sequence. The two reaction microchannels located on the outside are cracking reaction microchannels 12 with an ammonia cracking catalyst coating 121 coated on the inner wall surface, which provide catalytic cracking reaction of ammonia. The catalyst can be ruthenium, nickel, iron or high entropy alloy, and ruthenium catalyst is preferred; the reaction microchannel in the middle is a combustion channel 13 with an ammonia combustion catalyst coating 131 coated on the inner wall surface, which provides catalytic combustion of the mixed gas after ammonia cracking. The catalyst can be platinum, palladium, rhodium, or cerium, and platinum catalyst is preferred.

[0039] like Figure 1 One end of the three reaction microchannels (i.e., the two cracking reaction microchannels 12 on both sides and the combustion channel 13 in the middle) is connected together, and the end is provided with an air inlet 132 aimed at the combustion channel 13; the compressor 3 is connected to the air inlet 132 to provide compressed air for the burner 1, and a flow regulating valve can also be set in the pipeline for conveying compressed air.

[0040] An ammonia inlet 122 is provided at the other end of the cracking reaction microchannel 12 that is not connected to each other; the high-pressure container ammonia storage cylinder 2 stores compressed ammonia to provide ammonia to the cracking reaction microchannel 12 in the burner 1, and a flow regulating valve is provided in the pipeline connecting the ammonia storage cylinder 2 to the ammonia inlet 122 to accurately control the ammonia flow.

[0041] The other end of the combustion channel 13 that is not connected to each other is provided with an exhaust gas outlet 133, which is connected to the turbine 4 to input the high-temperature exhaust gas into the turbine 4; the turbine 4 is the power system of the device, and rotates under the drive of the high-temperature exhaust gas to generate mechanical energy, which can be used for power generation and can also be used to drive other mechanical equipment.

[0042] The thermophotovoltaic unit 5 is disposed outside the shell 11 of the burner 1, and receives heat generated by the combustion of the mixed gas in the combustion channel 13 and conducted to the outside through the shell 11 to generate electricity.

[0043] In a second aspect of the present invention, Figure 2 As shown, an embodiment of the present invention provides a micro ultra-low emission ammonia combustion method based on catalytic cracking and combustion, comprising the following steps:

[0044] S1: Ammonia is introduced into the cracking reaction microchannel in the burner, and the ammonia is fully contacted with the ammonia cracking catalyst to cause a catalytic cracking reaction;

[0045] S2: passing air into the combustion channel from one end of the three reaction microchannels in the burner that are connected to each other;

[0046] S3: The mixed gas generated by the catalytic cracking of ammonia in the cracking reaction microchannel enters the combustion channel together with the air, fully contacts with the ammonia combustion catalyst, and a catalytic combustion reaction occurs;

[0047] S4: The high-temperature exhaust gas obtained from the combustion is discharged from the burner.

[0048] As a better implementation, in the above technical solution:

[0049] In S1, the ammonia cracking catalyst used is ruthenium, nickel, iron or high entropy alloy, and the ruthenium catalyst is more preferred.

[0050] In S3, the ammonia combustion catalyst used is platinum, palladium, rhodium, or cerium, with platinum catalyst being more preferred; the heat generated during the catalytic combustion of the mixed gas is conducted through the burner shell to the thermal photovoltaic power generation device to perform photovoltaic power generation.

[0051] In S4, the high-temperature exhaust gas discharged from the burner is input into the turbine to drive the turbine to generate electricity.

[0052] A specific implementation of the technical solution of the present invention is as follows Figure 1 and Figure 2 As shown:

[0053] First, the ammonia gas cylinder 2 is opened, and ammonia is input into the cracking reaction microchannel 12 through the ammonia inlet 122. The flow rate regulating valve is used to control the ammonia flow rate entering the cracking reaction microchannel 12 to ensure stability. The catalyst in the ammonia cracking catalyst coating 121 uniformly attached to the inner wall surface of the cracking reaction microchannel 12 has excellent catalytic performance and can promote the catalytic cracking reaction of ammonia. During the reaction, the input ammonia not only fully contacts the ammonia cracking catalyst to undergo a catalytic cracking reaction, but also undergoes a gas phase cracking reaction in the middle of the channel. The two reactions jointly generate a mixed gas product including hydrogen, nitrogen and residual unreacted ammonia.

[0054] Secondly, the compressor 3 is started to input compressed air into the combustion channel 13 through the air inlet 132, and the gas flow is regulated by the flow regulating valve arranged in the pipeline.

[0055] While the compressed air is input into the combustion channel 13, the mixed gas after the cracking of ammonia also enters the combustion channel 13 with the air and is mixed with the air. The catalyst in the ammonia combustion catalyst coating 131 attached to the inner wall of the combustion channel 13 can promote the catalytic combustion reaction of the mixed gas, ensuring the high efficiency and stability of its combustion process. In addition, the mixed gas not only fully contacts with the ammonia combustion catalyst to undergo catalytic combustion reaction, but also undergoes gas phase combustion reaction in the channel.

[0056] Finally, the high-temperature exhaust gas generated by the combustion enters the turbine 4 through the exhaust gas outlet 133, and the high-temperature exhaust gas drives the turbine 4 to rotate. The heat generated in the combustion channel 13 is transferred to the walls on both sides by heat conduction, thereby heating the cracking reaction microchannels 12 on both sides, promoting the full progress of the cracking reaction, and realizing the self-sustaining combustion of the combustion device. Furthermore, the heat generated by the combustion of the mixed gas in the combustion channel 13 is conducted outward through the shell 11 of the burner 1. The shell 11 is designed as an efficient heat conduction material, which can effectively transfer heat to the thermophotovoltaic unit 5. The thermophotovoltaic unit 5 uses the thermophotovoltaic effect to convert the received heat into electrical energy, further improving the energy utilization efficiency of the entire device.

[0057] The micro ultra-low emission ammonia combustion device and method based on catalytic cracking and combustion provided by the present invention realize the efficient and low-pollution combustion of ammonia through catalytic cracking and catalytic combustion technology, and convert the energy generated by combustion into mechanical energy and electrical energy through a turbine and a thermal photovoltaic unit. The combustion device has a compact design, stable performance, and simple operation, and has both significant environmental and economic benefits, and has broad application prospects.

[0058] In the description of the present invention, the terms "upper", "lower", "center", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific placement or setting method; unless otherwise clearly specified and limited, the terms "connected" and "fixed" need to be understood in a broad sense, for example, "fixed" can be a fixed connection, a detachable connection, or directly integrated; "connected" can be a connection method such as a mechanical connection or an electrical connection, and can be a direct connection or an indirect connection through a medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] For the above embodiments of the present invention, common knowledge such as the well-known specific structures and characteristics in the technical scheme has not been described in detail; each embodiment is described in a progressive manner, and the technical features involved in each embodiment can be combined with each other under the premise that there is no conflict between each other, and the same and similar parts between the embodiments can be referred to each other.

[0060] It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the above embodiments without departing from the principles of the present invention, and these improvements and modifications should also be regarded as falling within the protection scope of the present invention.

Claims

1. A micro ultra-low emission ammonia combustion device based on catalytic cracking and combustion, comprising a burner (1), a fuel input unit and an air input unit, characterized in that: in: The shell (11) of the burner (1) is divided into three reaction microchannels arranged in sequence, wherein the two reaction microchannels located on the outside are cracking reaction microchannels (12) having an ammonia cracking catalyst coating (121) coated on the inner wall surface, and are used for catalytic cracking reaction of ammonia; the reaction microchannel in the middle is a combustion channel (13) having an ammonia combustion catalyst coating (131) coated on the inner wall surface, and is used for catalytic combustion of mixed gas after cracking ammonia; One end of the three reaction microchannels is connected together, and the end is provided with an air inlet (132) aimed at the combustion channel (13), and the air input unit is connected to the air inlet (132) to input air; the other end of the cracking reaction microchannel (12) that is not connected together is provided with an ammonia inlet (122), and the fuel input unit is connected to the ammonia inlet (122) to input ammonia; the other end of the combustion channel (13) that is not connected together is provided with an exhaust gas outlet (133) for discharging high-temperature exhaust gas.

2. The device according to claim 1, characterized in that The fuel input unit comprises an ammonia gas storage cylinder (2), and the ammonia gas storage cylinder 2 is connected to the ammonia gas inlet (122) to transport ammonia gas to the cracking reaction microchannel (12).

3. The device according to claim 1, characterized in that The air input unit comprises a compressor (3), and the compressor (3) is connected to the air inlet (132) to introduce compressed air into the combustion channel (13).

4. The device according to claim 1, characterized in that It also includes a turbine (4), which is connected to the exhaust gas outlet (133) and driven by the high-temperature exhaust gas discharged from the combustion channel (13).

5. The device according to claim 1, characterized in that It also comprises a thermophotovoltaic unit (5), which is arranged outside the shell (11) and generates electricity using heat energy conducted from the shell (11).

6. The device according to any one of claims 1 to 5, characterized in that The material of the ammonia cracking catalyst coating (121) is ruthenium, nickel, iron or a high entropy alloy; the material of the ammonia combustion catalyst coating (131) is platinum, palladium, rhodium or cerium.

7. A micro-ultra-low emission ammonia combustion method based on catalytic cracking and combustion using the micro-ultra-low emission ammonia combustion device based on catalytic cracking and combustion according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: Ammonia gas is introduced into the cracking reaction microchannel in the burner, and the ammonia gas is fully contacted with the ammonia cracking catalyst to cause a catalytic cracking reaction; Step 2: passing air into the combustion channel from one end of the three reaction microchannels in the burner that are connected together; Step 3: The mixed gas generated by the catalytic cracking of ammonia in the cracking reaction microchannel enters the combustion channel together with the air, fully contacts with the ammonia combustion catalyst, and a catalytic combustion reaction occurs; Step 4: Expel the high-temperature exhaust gas obtained from combustion from the burner.

8. The method according to claim 7, characterized in that In step 3, the heat generated by the catalytic combustion is transferred to the thermal photovoltaic power generation device to generate electricity.

9. The method according to claim 7, characterized in that: In step 4, the high-temperature exhaust gas discharged from the burner is used to drive the turbine.

10. The method according to any one of claims 7 to 9, characterized in that: The ammonia cracking catalyst in step 1 is ruthenium, nickel, iron or high entropy alloy; the ammonia combustion catalyst in step 3 is platinum, palladium, rhodium or cerium.

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