Microscale ultra-low emission ammonia combustion device and method based on catalytic cracking and combustion

Abstract

The embodiment of the present application provides a micro ultra-low emission ammonia combustion device based on catalytic cracking and combustion, which comprises a burner, a fuel input unit, an air input unit, a turbine and a thermal photovoltaic unit. The burner is a pre-cracking ammonia burner, which comprises two cracking reaction microchannels with ammonia cracking catalyst coating on the inner wall surfaces and one combustion channel with ammonia combustion catalyst coating on the inner wall surface. Ammonia is catalytically cracked in the cracking reaction microchannels, the generated mixed gas is catalytically combusted in the combustion channel, and further power generation is achieved by using heat radiation and high-temperature tail gas. The efficient and low-pollution combustion of ammonia can be realized, and the energy generated by combustion can be converted into mechanical energy and electrical energy through the turbine and the thermal photovoltaic unit. The combustion device is compact in design, stable in performance and simple in operation, and has significant environmental and economic benefits. The embodiment of the present application also provides a method using the device.

Description

TECHNICAL FIELD

[0001] The present application 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. BACKGROUND

[0002] In recent years, alternative fuels and clean combustion technologies have gradually become an important development trend for reducing carbon emissions. Ammonia, as one of the highest global production chemical products, has the significant advantage of no carbon emission in the combustion process. The high octane value of ammonia can also effectively improve the anti-knock performance of the engine. Compared with another carbon-free fuel, hydrogen, ammonia has a significant advantage in storage and transportation. At present, it has mature supporting facilities and can be safely and conveniently stored and transported. However, ammonia as fuel also faces some challenges, including a narrow flammable boundary, unstable combustion, high ignition temperature, and long ignition delay time. In addition, the nitrogen element in ammonia is easy to combine with oxygen during combustion, thereby releasing a large amount of nitrogen oxides NO x , such as NO, NO2 and N2O, which 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 in the ignition and combustion process of ammonia, a reasonable idea is to first partially crack ammonia to generate hydrogen, and then burn the ammonia-hydrogen mixture as fuel. The cracking process of ammonia has been studied for many years, and the reaction conditions are relatively mild. The use of catalysts can significantly reduce the temperature of the cracking reaction and improve the conversion rate of ammonia. Among them, ruthenium (Ru) and platinum (Pt) catalysts are commonly used ammonia cracking and ammonia combustion catalysts, which can exhibit excellent performance at low temperature and near 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, it requires a high-temperature environment to maintain its occurrence. Past research has mainly focused on how to achieve efficient ammonia cracking, and there is relatively little research on the subsequent combustion process of ammonia catalytic cracking products, and there is a lack of self-sustaining burners designed based on this idea. Therefore, it is urgent to develop an ammonia burner that can self-sustain clean combustion by using ruthenium and platinum as catalysts to obtain hydrogen by pre-cracking ammonia, in order to effectively improve the combustion performance of ammonia for fuel applications. SUMMARY

[0005] The present application aims to solve the problem of the prior art that there is a lack of ammonia burners based on ammonia catalytic cracking and subsequent catalytic combustion for self-sustaining clean combustion, and provides a micro ultra-low emission ammonia combustion device and method based on catalytic cracking and combustion, which realizes self-sustaining clean combustion of ammonia through catalytic pre-cracking and subsequent catalytic combustion of ammonia, so as to solve the problems of narrow flammable boundary, difficult ignition, unstable combustion and high nitrogen oxide emission of ammonia combustion, and effectively improve the combustion performance of ammonia.

[0006] The technical scheme is as follows:

[0007] The micro ultra-low emission ammonia combustion device based on catalytic cracking and combustion provided by the embodiments of the present application 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 in sequence, two of which on the outside are cracking reaction microchannels with an ammonia cracking catalyst coating on the inner wall surface for catalytic cracking reaction of ammonia gas; the one in the middle is a combustion channel with an ammonia combustion catalyst coating on the inner wall surface 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 aligned with 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 not connected together is provided with an ammonia gas inlet, and the fuel input unit is connected to the ammonia gas inlet to input ammonia gas; the other end of the combustion channel not connected together is provided with a tail gas outlet for high-temperature tail gas discharge.

[0009] As a preferred fuel input unit, the fuel input unit comprises an ammonia storage cylinder connected to the ammonia gas inlet to deliver ammonia gas to the cracking reaction microchannel.

[0010] As a preferred air input unit, the air input unit comprises a compressor connected to the air inlet to input compressed air to the combustion channel.

[0011] Preferably, the device further comprises a turbine connected to the tail gas outlet, and the high-temperature tail gas discharged from the combustion channel drives the turbine.

[0012] Preferably, the device further comprises a thermal photovoltaic unit arranged outside the shell and generating electricity with the heat energy conducted by the shell.

[0013] As a preferred solution to the above technical scheme, the ammonia cracking catalyst coating can use ruthenium, nickel, iron or high-entropy alloy, etc. ammonia cracking catalyst, and further preferably ruthenium catalyst; the ammonia combustion catalyst coating can use platinum, palladium, rhodium, or cerium, etc. ammonia combustion catalyst, and further preferably platinum catalyst.

[0014] The above-mentioned gas conveying pipeline can be provided with valves at each control part of the pipeline, and corresponding valves can be configured for different pipe sections, such as various flow regulating valves or one-way valves, which can be configured according to actual working conditions, and details are not described herein.

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

[0016] Step 1: ammonia is introduced into the cracking reaction micro-channel in the burner, and the ammonia is in full contact with the ammonia cracking catalyst to generate a catalytic cracking reaction;

[0017] Step 2: air is introduced into the combustion channel from one end of the three reaction micro-channels of the burner;

[0018] Step 3: the mixed gas generated by the catalytic cracking of ammonia in the cracking reaction micro-channel enters the combustion channel together with the air, and is in full contact with the ammonia combustion catalyst to generate a catalytic combustion reaction;

[0019] Step 4: high-temperature tail gas obtained by combustion is discharged 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 for power generation.

[0021] As a preferred embodiment of step 4, a turbine is driven by the high-temperature tail gas discharged from the burner.

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

[0023] The above-mentioned technical solution of the embodiment of the present application, through in-depth research on the ammonia cracking combustion and the combustion performance of 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, adopts a pre-cracking type ammonia burner, and realizes self-sustaining clean combustion of ammonia. The beneficial effects are as follows:

[0024] 1. The use of catalytic cracking technology and catalytic combustion technology for ammonia cracking and combustion only requires two raw materials, ammonia and air, without the need for other raw material inputs. The device can achieve self-sustaining combustion without the need for additional energy input, greatly reduces nitrogen oxide emissions, and the designed system is small and simple, reducing manufacturing and operating costs;

[0025] 2. It creates conditions for the full utilization of ammonia. Using high-temperature tail gas for reheating can appropriately raise 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 combustible boundary, difficulty in ignition, and high nitrogen oxide emissions caused by direct combustion of ammonia.

[0026] 3. The burner casing wall can transfer heat to generate photovoltaic or thermoelectric power. The exhaust gas outlet of the burner can be connected to a small turbine to drive power, thereby realizing the full utilization of energy. Attached Figure Description

[0027] The following figures are provided to further illustrate the invention and form part of the specification. They are used together with the detailed embodiments to explain the invention, but do not constitute a limitation thereof. 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 This is a schematic diagram 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] [Explanation of Key Component Symbols]

[0031] 1-Burner; 11-Shell;

[0032] 12- Pyrolysis reaction microchannel; 121- Ammonia pyrolysis catalyst coating; 122- Ammonia inlet;

[0033] 13-Combustion channel; 131-Ammonia combustion catalyst coating; 132-Air inlet; 133-Exhaust gas outlet;

[0034] 2-Ammonia storage cylinder; 3-Compressor; 4-Turbine; 5-Thermophotovoltaic unit. Detailed Implementation

[0035] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0036] This invention addresses existing problems by providing 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, achieving a low-pollution and high-efficiency combustion process.

[0037] To achieve the above technical solution, such as 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 storage cylinder 2, a compressor 3, a turbine 4, and a thermophotovoltaic unit 5, wherein:

[0038] The shell 11 of the combustor 1 is divided into three reaction microchannels arranged in sequence, the two reaction microchannels on the outer side are the cracking reaction microchannels 12 with the inner wall surface coated with an ammonia cracking catalyst coating 121, for the catalytic cracking reaction of ammonia, and the catalyst can be ruthenium, nickel, iron or high-entropy alloy, and ruthenium catalyst is preferred; the reaction microchannel in the middle is the combustion channel 13 with the inner wall surface coated with an ammonia combustion catalyst coating 131, for the catalytic combustion of the mixed gas after ammonia cracking, and the catalyst can be platinum, palladium, rhodium or cerium, and platinum catalyst is preferred.

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

[0040] The other end of the cracking reaction microchannel 12 not connected together is provided with an ammonia inlet 122; the high-pressure container ammonia storage cylinder 2 stores compressed ammonia, which is used to provide ammonia to the cracking reaction microchannel 12 in the combustor 1, and a flow regulating valve is provided in the pipeline connecting the ammonia storage cylinder 2 to the ammonia inlet 122, which can accurately control the flow of ammonia.

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

[0042] The thermal photovoltaic cell 5 is arranged outside the shell 11 of the combustor 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] As shown in Figure 2 , the embodiment of the present application provides a micro ultra-low emission ammonia combustion method based on catalytic cracking and combustion, comprising the following steps:

[0044] S1: passing ammonia into the cracking reaction microchannel in the combustor, and the ammonia is in full contact with the ammonia cracking catalyst to occur a catalytic cracking reaction;

[0045] S2: passing air from the common connection end of the three reaction microchannels in the combustor into the combustion channel;

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

[0047] S4: high-temperature tail gas obtained by combustion is discharged from the combustor.

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

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

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

[0051] In S4, the high-temperature tail gas discharged from the combustor is input into a turbine to drive turbine power generation.

[0052] One specific implementation of the technical solution of the present application is shown in Figure 1 and Figure 2 as shown:

[0053] First, open the ammonia storage cylinder 2, input ammonia gas into the cracking reaction microchannel 12 through the ammonia gas inlet 122, and ensure stable ammonia gas flow into the cracking reaction microchannel 12 by controlling the flow regulating valve. 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, which can promote the catalytic cracking reaction of ammonia gas. In the reaction process, not only does the input ammonia gas fully contact the ammonia cracking catalyst to undergo catalytic cracking reaction, but also gas phase cracking reaction occurs in the middle of the channel, and the two reactions together generate mixed gas products including hydrogen, nitrogen, and residual unreacted ammonia.

[0054] Second, start the air compressor 3, input compressed air into the combustion channel 13 through the air inlet 132, and adjust the gas flow by the flow regulating valve provided in the pipeline.

[0055] At the same time as inputting compressed air into the combustion channel 13, the mixed gas after ammonia cracking also enters the combustion channel 13 with the air to achieve mixing. The catalyst in the ammonia combustion catalyst coating 131 attached to the inner wall surface of the combustion channel 13 can promote the catalytic combustion reaction of the mixed gas, ensuring efficient and stable combustion process, in addition, the mixed gas not only fully contacts the ammonia combustion catalyst to undergo catalytic combustion reaction, but also gas phase combustion reaction occurs in the channel.

[0056] Finally, the high-temperature exhaust gas generated by combustion enters the turbine 4 through the exhaust outlet 133, and the high-temperature exhaust gas drives the turbine 4 to rotate. The heat generated in the combustion channel 13 is then transferred to the two side walls by heat conduction, thereby heating the cracking reaction microchannels 12 located on both sides and promoting the full progress of the cracking reaction, achieving self-sustaining combustion of the combustion device. Further, the heat generated by the combustion of the mixture in the combustion channel 13 is conducted outwardly through the shell 11 of the burner 1, which is designed as a high-efficiency heat conduction material, capable of effectively transferring heat to the thermal photovoltaic unit 5. The thermal photovoltaic unit 5 utilizes the thermal photovoltaic 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 application realizes efficient and low-pollution combustion of ammonia gas through catalytic cracking and catalytic combustion technology, and converts the energy generated by combustion into mechanical energy and electrical energy through a turbine and a thermal photovoltaic unit. The combustion device is compact in design, stable in performance, easy to operate, has significant environmental and economic benefits, and has a wide application prospect.

[0058] In the description of the present application, the terms "upper", "lower", "center", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific placement or setting method; unless otherwise explicitly specified and limited, the terms "connection", "fixation" need to be understood broadly, for example, "fixation" can be fixed connection, detachable connection or direct integration; "connection" can be mechanical connection or electrical connection, etc. Connection methods can be direct connection or indirect connection through media. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0059] For the above embodiments of the present application, the specific structures and characteristics of the technical solutions known in the art are not described in detail; the embodiments are described in a progressive manner, and the technical features involved in each embodiment can be combined with each other without conflicting with each other, and the same or similar parts between the embodiments can be referred to each other.

[0060] It should be noted that for those skilled in the art, without departing from the principles of the present application, some improvements and refinements can be made to the above embodiments, and these improvements and refinements should also be considered to fall within the protection scope of the present application.

Claims

1. A catalytic cracking and combustion based micro ultra-low emission ammonia combustion device comprising a burner (1), a fuel input unit and an air input unit, characterized in that, Wherein: The shell (11) of the burner (1) is divided into three reaction microchannels arranged in sequence, the two outer reaction microchannels are cracking reaction microchannels (12) with ammonia cracking catalyst coating (121) on the inner wall surface for catalytic cracking reaction of ammonia; the middle reaction microchannel is a combustion channel (13) with ammonia combustion catalyst coating (131) on the inner wall surface 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 (132) aligned with 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) not connected together is provided with an ammonia gas inlet (122), and the fuel input unit is connected to the ammonia gas inlet (122) to input ammonia gas; the other end of the combustion channel (13) not connected together is provided with a tail gas outlet (133) for high-temperature tail gas discharge; It also includes a thermal photovoltaic unit (5) arranged outside the shell (11) to generate electricity with the heat conducted by the shell (11).

2. The apparatus of claim 1, wherein, The fuel input unit includes an ammonia storage cylinder (2) connected to the ammonia gas inlet (122) to deliver ammonia gas to the cracking reaction microchannel (12).

3. The apparatus of claim 1, wherein, The air input unit includes a compressor (3) connected to the air inlet (132) to pass compressed air into the combustion channel (13).

4. The apparatus of claim 1, wherein, It also includes a turbine (4) connected to the tail gas outlet (133), and the high-temperature tail gas discharged from the combustion channel (13) drives the turbine (4).

5. The device of any one of claims 1 to 4, wherein, The material of the ammonia cracking catalyst coating (121) is ruthenium, nickel, iron or high-entropy alloy; the material of the ammonia combustion catalyst coating (131) is platinum, palladium, rhodium or cerium.

6. A catalytic cracking and combustion based micro- ultra-low NOx ammonia combustor method using the catalytic cracking and combustion based micro- ultra-low NOx ammonia combustor according to any one of claims 1 to 5, characterized in that, The steps include: Step 1: pass ammonia into the cracking reaction microchannel in the burner, and the ammonia fully contacts with the ammonia cracking catalyst to occur catalytic cracking reaction; Step 2: pass air from the common connection end of the three reaction microchannels in the burner into the combustion channel; Step 3: the mixed gas produced by catalytic cracking of ammonia in the cracking reaction microchannel enters the combustion channel with air, fully contacts with the ammonia combustion catalyst, and occurs catalytic combustion reaction; Step 4: discharge the high-temperature tail gas obtained by combustion from the burner.

7. The method of claim 6, wherein, In step 3, the heat generated by catalytic combustion is conducted to the thermal photovoltaic power generation device for power generation.

8. The method of claim 6, wherein, In step 4, the turbine is driven by the high-temperature tail gas discharged from the burner.

9. The method according to any one of claims 6 to 8, 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.

Images