A near-zero carbon emission engine system and working method thereof

Abstract

The present invention provides a near-zero carbon emission engine system and its working method, belonging to the fields of vehicle engines and exhaust aftertreatment. It solves the problems of long cold start time of ammonia-hydrogen engines, high NO x gas emissions, and the disadvantages of urea SCR technology. It includes a liquid ammonia tank, a diesel tank, a dual-fuel engine, a catalytic cracking reactor, an adsorptive solid ammonia storage NOx removal device, and a decarbonization device. The dual-fuel engine in the system can burn ammonia-diesel mixtures and ammonia-hydrogen mixtures respectively under cold start and stable operation conditions, enabling the normal operation of the vehicle during engine cold start and shortening the warm-up time. Among them, hydrogen is obtained by catalytically cracking part of the ammonia in the intake air. The system is also equipped with an exhaust aftertreatment device for denitrification and decarbonization, ultimately achieving the effect of near-zero carbon and zero pollution emissions of the system. The present invention is applicable to the rapid cold start of ammonia-fuel engines and zero-pollution emissions of exhaust gases.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle engines and exhaust gas aftertreatment thereof, and in particular relates to a near-zero carbon emission engine system and a working method thereof. Background Art

[0002] Engines usually use fossil fuels such as gasoline and diesel, and the combustion process produces a large amount of carbon dioxide (CO2), which seriously aggravates the process of global warming.

[0003] At present, the main zero-carbon fuels for vehicles are hydrogen (H2) and ammonia (NH3). Among them, hydrogen has great problems in storage, transportation, safety, etc.; while ammonia can be easily stored in plastic tanks for easy transportation, and existing gas stations can fully meet the filling needs of liquid ammonia. In addition, compared with hydrogen, ammonia also has advantages such as high energy density (1.5 times that of liquid hydrogen) and high safety. Therefore, ammonia has great application prospects as a zero-carbon fuel for engines. However, due to the characteristics of pure ammonia such as slow combustion speed, low combustion temperature, and difficult ignition, it is necessary to ignite fuel to assist combustion to achieve stable operation of ammonia engines. Common ignition fuels include acetylene, dimethyl ether, gasoline, diesel, hydrogen, etc. Among them, hydrogen is a zero-carbon fuel with extremely low ignition energy, fast flame propagation speed, and high combustion temperature. Ammonia-hydrogen mixed combustion engines have received widespread attention. At present, the sources of hydrogen for ammonia-hydrogen mixed engines are mainly divided into two types: one is to add a hydrogen storage container to directly transport hydrogen to the engine for combustion; the other is to catalytically crack part of the ammonia under the combined action of high temperature and catalyst to produce hydrogen, and then pass the generated hydrogen into the engine for combustion.

[0004] An existing ammonia engine system includes an ammonia supply device, an ammonia cracking device, an ammonia heating device, an ammonia engine, a selective catalytic reduction device, an exhaust gas detection device, a heat exchanger, a control circuit, and a temperature sensor. The system utilizes the exhaust waste heat of the ammonia-hydrogen mixed combustion and the heater to heat the ammonia cracking device to catalytically crack ammonia to obtain hydrogen. However, when the engine is cold-started, the heat required for the ammonia catalytic cracking reaction can only be provided by the heater, which not only consumes a lot of additional electric energy, but also requires a long time to heat the ammonia cracking device to reach the temperature for efficient catalytic cracking of ammonia, resulting in a long cold start time for the automobile engine and inability to operate normally. In view of this, it is of great significance to invent a low-carbon engine system that can achieve efficient operation in both cold start and stable operation modes.

[0005] Ammonia fuel engine combustion produces a large amount of NO xPollutants, the most widely used denitrification technology in automobiles is urea SCR technology, but automotive urea solution is easy to crystallize, the production cost and use cost are high, and the ammonia content of automotive urea solution is very low (only 18.42%), resulting in a large consumption of urea solution. On the other hand, there is no carbon capture device in existing vehicles, and there is little research on vehicle-mounted decarbonization systems. Traditional industrial flue gas carbon dioxide treatment technology is mostly large absorption tower structure, which cannot be directly used on vehicles with limited space.

[0006] In view of the long cold start time and NO x The present invention proposes a near-zero carbon emission engine system, which solves the problem of slow cold start and uses an adsorption ammonia storage-SCR device and a carbon capture device to capture NO in the engine exhaust gas in dual-mode. x By removing and absorbing CO2 respectively, the system can achieve near zero carbon and zero pollution emissions. Summary of the invention

[0007] In view of this, the invention aims to propose a near-zero carbon emission engine system to solve the problems of long cold start time and NO x High gas emissions and shortcomings of urea SCR technology.

[0008] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0009] A near-zero carbon emission engine system, comprising a liquid ammonia tank, a diesel tank, a dual-fuel engine, a catalytic cracking reactor, an adsorption-type solid ammonia storage NOx removal device and a decarbonization device;

[0010] The liquid ammonia tank and the diesel tank are each connected to the air intake of the dual-fuel engine through a pipeline, the air intake is connected to the outside atmosphere, the outlet of the liquid ammonia tank is connected to the reaction channel inlet of the catalytic cracking reactor through a pipeline, the reaction channel outlet of the catalytic cracking reactor is connected to the air intake of the dual-fuel engine, the tail gas outlet of the dual-fuel engine is connected to the tail gas waste heat recovery inlet of the catalytic cracking reactor, the tail gas waste heat recovery outlet during the catalytic cracking reaction period is connected to the adsorption-type solid ammonia storage and NOx removal device, the adsorption-type solid ammonia storage and NOx removal device is connected to the atmosphere through the tail gas purification pipeline, the adsorption-type solid ammonia storage and NOx removal device is connected to the inlet of the decarbonization device, and the outlet of the decarbonization device is connected to the tail gas purification pipeline;

[0011] A first ammonia flow electronically controlled valve is provided on the pipeline between the outlet of the liquid ammonia tank and the inlet of the reaction flow channel of the catalytic cracking reactor, a second ammonia flow electronically controlled valve is provided on the pipeline connecting the outlet of the liquid ammonia tank and the air intake of the dual-fuel engine, a third tail gas flow electronically controlled valve is provided on the tail gas purification pipeline, and a fourth tail gas flow electronically controlled valve is provided on the pipeline connecting the adsorption solid ammonia storage NOx removal device and the inlet of the decarbonization device;

[0012] The catalytic cracking reactor is used for exchanging heat with the tail gas and catalyzing the cracking of ammonia to produce hydrogen. The adsorption-type solid ammonia storage and NOx removal device is used for denitrifying the tail gas. The decarbonization device is used for decarbonizing the tail gas.

[0013] Furthermore, the adsorption-type solid ammonia storage NOx removal device comprises an adsorption-type ammonia storage tank and an SCR reactor, the exhaust heat recovery outlet of the catalytic cracking reactor is respectively connected to the air inlet of the adsorption-type ammonia storage tank and the air inlet of the SCR reactor through pipelines, the air outlet of the adsorption-type ammonia storage tank is connected to the air inlet of the SCR reactor through a pipeline, the air outlet of the SCR reactor is respectively connected to the exhaust gas purification pipeline and the decarbonization device, and the ammonia outlet of the adsorption-type ammonia storage tank is connected to the reductant inlet of the SCR reactor through an ammonia pipeline;

[0014] A first exhaust gas flow electric control valve is provided on the pipeline between the exhaust gas waste heat recovery outlet of the catalytic cracking reactor and the air inlet of the adsorption ammonia storage tank, a second exhaust gas flow electric control valve is provided on the pipeline between the exhaust gas waste heat recovery outlet of the catalytic cracking reactor and the air inlet of the SCR reactor, and a third ammonia flow electric control valve is provided on the ammonia pipeline.

[0015] Furthermore, the decarbonization device includes an electronically controlled nozzle, a liquid storage tank and a carbon capture device. The gas outlet of the SCR reactor is connected to the liquid inlet of the liquid storage tank and the gas inlet of the carbon capture device through a spray pipeline, and an electronically controlled nozzle is arranged on the spray pipeline. The gas outlet of the carbon capture device is connected to the purification pipeline. A fourth exhaust gas flow electronically controlled valve is arranged on the spray pipeline near the gas outlet of the SCR reactor.

[0016] Furthermore, two electronically controlled nozzles are provided, namely electronically controlled nozzle one and electronically controlled nozzle two.

[0017] Furthermore, the carbon capture device is provided with a quaternary mixed amine solution of a certain proportion of monoethanolamine (MEA), dimethylaminoethanol (DMAE), triethanolamine (TEA) and piperazine (PZ).

[0018] Furthermore, the molar ratio of each substance in the quaternary mixed amine solution is MEA:DMAE:TEA:PZ=4:4:2:1.

[0019] Furthermore, a diesel flow electronically controlled valve is provided on the pipeline between the diesel tank outlet and the air intake of the dual-fuel engine.

[0020] Furthermore, an air flow electric control valve is provided at the air end of the air intake passage of the dual-fuel engine.

[0021] Furthermore, the catalytic cracking reactor also includes an electric heater, which is located inside the catalytic cracking reaction flow channel and provides auxiliary heating for the catalytic cracking reaction flow channel; an electric heating layer is wrapped around the outside of the adsorption ammonia storage tank and is used to preheat the adsorption ammonia storage tank.

[0022] Another purpose of the invention is to provide a working method of a near-zero carbon emission engine system, which specifically includes:

[0023] When the dual-fuel engine is cold-started, the second ammonia flow electronically controlled valve, the air flow electronically controlled valve, the diesel flow electronically controlled valve, the first exhaust gas flow electronically controlled valve, the second exhaust gas flow electronically controlled valve, the third ammonia flow electronically controlled valve, and the fourth exhaust gas flow electronically controlled valve are opened, and the first ammonia flow electronically controlled valve and the third exhaust gas flow electronically controlled valve are closed, and the dual-fuel engine burns ammonia and diesel mixed fuel;

[0024] The two fuels are fully premixed with air in the intake duct and then enter the dual-fuel engine for combustion. The high-temperature exhaust gas after combustion in the cylinder enters the exhaust gas waste heat recovery part of the catalytic cracking reactor to fully exchange heat with the catalytic cracking reaction flow channel. At the same time, the electric heater performs auxiliary heating on the catalytic cracking reaction flow channel. Under the joint action of the high-temperature exhaust gas and the electric heater, the catalytic cracking reaction flow channel is rapidly heated.

[0025] After the tail gas flows out of the catalytic cracking reactor, it enters the adsorption solid ammonia storage NOx removal device for tail gas denitrification. The tail gas after denitrification is decarbonized by the decarbonization device and then discharged into the atmosphere.

[0026] When the dual-fuel engine is running stably, the temperature in the catalytic cracking reaction flow channel of the catalytic cracking reactor should reach a certain temperature or above, at which time the first ammonia flow electronically controlled valve, the second ammonia flow electronically controlled valve, the air flow electronically controlled valve, the first tail gas flow electronically controlled valve, the second tail gas flow electronically controlled valve, the third ammonia flow electronically controlled valve and the third tail gas flow electronically controlled valve are opened, the diesel flow electronically controlled valve and the fourth tail gas flow electronically controlled valve are closed, part of the ammonia flowing out of the liquid ammonia tank enters the catalytic cracking reaction flow channel of the catalytic cracking reactor through the first ammonia flow electronically controlled valve, the ammonia is cracked into hydrogen and nitrogen, the hydrogen and nitrogen flows out from the catalytic cracking reaction flow channel outlet of the catalytic cracking reactor and flows into the engine intake pipe, and enters the dual-fuel engine for combustion after being fully premixed with the ammonia and air in the intake pipe; the dual-fuel engine burns ammonia and hydrogen mixed fuel;

[0027] The high-temperature exhaust gas after combustion in the cylinder enters the exhaust gas waste heat recovery part of the catalytic cracking reactor to fully exchange heat with the catalytic cracking reaction flow channel. After the exhaust gas flows out of the catalytic cracking reactor, it enters the adsorption-type solid ammonia storage NOx removal device for exhaust gas denitrification. The purified exhaust gas is discharged into the atmosphere through the purified exhaust gas pipeline.

[0028] Compared with the prior art, the beneficial effects of the near-zero carbon emission engine system created by the present invention are:

[0029] (1) The near-zero carbon emission engine system created by the present invention operates in two different modes. When the engine is cold started, diesel is used to assist the combustion of ammonia to achieve rapid warm-up. At the same time, the high-temperature exhaust gas generated by the combustion heats the catalyst layer, shortening the time for the catalyst layer to reach a suitable catalytic temperature, reducing the power consumption of the electric heater, and utilizing the waste heat of the exhaust gas, thereby improving the energy utilization efficiency and the overall efficiency of the system, and achieving normal operation of the engine when there is no hydrogen supply.

[0030] (2) The present invention creates a near-zero carbon emission engine system, the exhaust gas after-treatment system of which has the functions of denitrification and decarbonization at the same time. The proposed denitrification device overcomes the shortcomings of traditional automotive urea SCR technology, such as high production and use costs, very low ammonia content in urea solution, and easy crystallization at temperatures below -11°C, which makes it impossible to pyrolyze and obtain ammonia for denitrification. The present invention utilizes exhaust gas waste heat to heat the adsorption ammonia storage tank to desorb 100% high-purity ammonia, and uses multiple electronically controlled valves to control the flow of ammonia input into the SCR reactor, thereby greatly reducing the consumption of denitrification working fluid.

[0031] (3) The present invention creates a near-zero carbon emission engine system, in which a carbon capture device is provided to absorb a small amount of CO2 emissions generated by diesel-assisted combustion during the cold start phase. The quaternary mixed amine solution of monoethanolamine (MEA), dimethylaminoethanol (DMAE), triethanolamine (TEA) and piperazine (PZ) used has a very high carbon dioxide capture rate and can achieve a good decarbonization effect on exhaust gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0033] Figure 1 A schematic structural diagram of a near-zero carbon emission engine system according to an embodiment of the present invention.

[0034] Description of reference numerals:

[0035] 1. Liquid ammonia tank; 2. First ammonia flow electronically controlled valve; 3. Second ammonia flow electronically controlled valve; 4. Air flow electronically controlled valve; 5. Diesel tank; 6. Diesel flow electronically controlled valve; 7. Dual-fuel engine; 8. Catalytic cracking reactor; 9. First exhaust gas flow electronically controlled valve; 10. Second exhaust gas flow electronically controlled valve; 11. Adsorption ammonia storage tank; 12. Third ammonia flow electronically controlled valve; 13. SCR reactor; 14. Third exhaust gas flow electronically controlled valve; 15. Fourth exhaust gas flow electronically controlled valve; 16. Electronically controlled nozzle 1; 17. Electronically controlled nozzle 2; 18. Liquid storage tank; 19. Carbon capture device. DETAILED DESCRIPTION

[0036] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0038] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0039] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] like Figure 1 As shown, a near-zero carbon emission engine system includes a liquid ammonia tank 1, a diesel tank 5, a dual-fuel engine 7, a catalytic cracking reactor 8, an adsorption-type solid ammonia storage NOx removal device and a decarbonization device;

[0041] The liquid ammonia tank 1 and the diesel tank 5 are each connected to the air intake of the dual-fuel engine 7 through a pipeline, and the air intake is connected to the outside atmosphere. The outlet of the liquid ammonia tank 1 is connected to the reaction channel inlet of the catalytic cracking reactor 8 through a pipeline, and the reaction channel outlet of the catalytic cracking reactor 8 is connected to the air intake of the dual-fuel engine 7. The tail gas outlet of the dual-fuel engine 7 is connected to the tail gas waste heat recovery inlet of the catalytic cracking reactor 8. The tail gas waste heat recovery outlet during the catalytic cracking reaction period is connected to the adsorption-type solid ammonia storage and NOx removal device. The adsorption-type solid ammonia storage and NOx removal device is connected to the atmosphere through the tail gas purification pipeline. The adsorption-type solid ammonia storage and NOx removal device is connected to the inlet of the decarbonization device, and the outlet of the decarbonization device is connected to the tail gas purification pipeline.

[0042] A first ammonia flow electronically controlled valve 2 is provided on the pipeline between the outlet of the liquid ammonia tank 1 and the inlet of the reaction flow channel of the catalytic cracking reactor 8, a second ammonia flow electronically controlled valve 3 is provided on the pipeline connecting the outlet of the liquid ammonia tank 1 and the intake channel of the dual-fuel engine 7, a third tail gas flow electronically controlled valve 14 is provided on the tail gas purification pipeline, and a fourth tail gas flow electronically controlled valve 15 is provided on the pipeline connecting the adsorption solid ammonia storage NOx removal device and the inlet of the decarbonization device;

[0043] The catalytic cracking reactor 8 is used for exchanging heat with the tail gas and catalyzing the cracking of ammonia to produce hydrogen. The adsorption-type solid ammonia storage and NOx removal device is used for denitrifying the tail gas. The decarbonization device is used for decarbonizing the tail gas.

[0044] The adsorption-type solid ammonia storage and NOx removal device comprises an adsorption-type ammonia storage tank 11 and an SCR reactor 13. The exhaust heat recovery outlet of the catalytic cracking reactor 8 is respectively connected to the air inlet of the adsorption-type ammonia storage tank 11 and the air inlet of the SCR reactor 13 through pipelines, the air outlet of the adsorption-type ammonia storage tank 11 is connected to the air inlet of the SCR reactor 13 through a pipeline, the air outlet of the SCR reactor 13 is respectively connected to the exhaust gas purification pipeline and the decarbonization device, and the ammonia outlet of the adsorption-type ammonia storage tank 11 is connected to the reducing agent inlet of the SCR reactor 13 through an ammonia pipeline;

[0045] A first exhaust gas flow electric control valve 9 is provided on the pipeline between the exhaust gas waste heat recovery outlet of the catalytic cracking reactor 8 and the air inlet of the adsorption ammonia storage tank 11, a second exhaust gas flow electric control valve 10 is provided on the pipeline between the exhaust gas waste heat recovery outlet of the catalytic cracking reactor 8 and the air inlet of the SCR reactor 13, and a third ammonia flow electric control valve 12 is provided on the ammonia pipeline.

[0046] The adsorption ammonia storage tank 11 and the SCR reactor 13 are used to complete ammonia storage and desorption, selective catalytic reduction reaction and other tasks. The adsorption ammonia storage tank NOx removal system has a wide operating temperature range and can achieve a high NOx conversion rate in the low temperature range of 50°C-100°C. The adsorption ammonia storage tank 11 is wrapped with an electric heating layer on the outside. The device is driven by electric heating and exhaust gas. Before the vehicle is started, the system will be electrically preheated to quickly inject ammonia into the SCR reactor 13. The adsorption ammonia storage tank 11 uses adsorption materials to adsorb and store ammonia flowing into the tank under specific conditions. In the ammonia desorption and NOx removal process, the exhaust gas after heat exchange in the catalytic cracking reactor 8 will be passed into the adsorption ammonia storage tank 11 through the first exhaust gas flow electronically controlled valve 9. The first exhaust gas flow electronically controlled valve 9 controls the internal temperature of the adsorption ammonia storage tank 11 by controlling the exhaust gas flow entering the adsorption ammonia storage tank 11. The second exhaust gas flow electronically controlled valve 10 is used to ensure normal exhaust gas flow and exhaust safety. When the pressure of the adsorption ammonia storage tank 11 increases to the desorption pressure after being heated, ammonia will be released. The ammonia is passed into the SCR reactor 13 to react chemically with NOx to denitrify the exhaust gas. The third ammonia flow electronically controlled valve 12 is used to control the ammonia flow entering the SCR reactor 13.

[0047] The decarbonization device includes an electronically controlled nozzle, a liquid storage tank 18 and a carbon capture device. The gas outlet of the SCR reactor 13 is connected to the liquid inlet of the liquid storage tank 18 and the gas inlet of the carbon capture device through a spray pipeline. The electronically controlled nozzle is arranged on the spray pipeline. The gas outlet of the carbon capture device is connected to the purification pipeline. A fourth tail gas flow electronically controlled valve 15 is arranged on the spray pipeline near the gas outlet of the SCR reactor 13. Two electronically controlled nozzles are arranged, namely electronically controlled nozzle 1 16 and electronically controlled nozzle 2 17.

[0048] The electronically controlled nozzle 16 and the electronically controlled nozzle 2 17 cool the exhaust gas flowing out of the SCR reactor 13 by spraying liquid water into the pipeline, so that the exhaust gas temperature drops to below 65°C. The liquid water sprayed by the electronically controlled nozzle is blown into the liquid storage tank 18 by the exhaust gas for collection. The carbon capture device 19 mainly includes a quaternary mixed amine solution of a certain proportion of monoethanolamine (MEA), dimethylaminoethanol (DMAE), triethanolamine (TEA) and piperazine (PZ). The molar ratio of the solution can include monoethanolamine (MEA): dimethylaminoethanol (DMAE): triethanolamine (TEA): piperazine (PZ) = (1-9): (1-9): (1-9): (1-9); specifically, the preferred ratio can be a mixture according to the molar ratio of MEA: DMAE: TEA: PZ = 4:4:2:1, and the corresponding ratio can also be adjusted according to actual conditions.

[0049] Compared with traditional ammonia solution and monoethanolamine solution, it has better performance in CO2 absorption performance and temperature adaptability. MEA is a primary amine with a fast absorption rate but high regeneration energy; DMAE has good absorption performance but a slow absorption rate. The mixed amine solution composed of the two is superior to the monoamine solvent in terms of desorption rate and energy consumption in adsorbing carbon dioxide; in order to solve the characteristics of fast instantaneous exhaust rate and high initial exhaust temperature of automobile exhaust, TEA and PZ are further added to enhance the absorption rate. At the same time, due to the special ring structure of PZ, it has high heat resistance and oxidation resistance, which improves the overall temperature adaptability of the solution, making the quaternary mixed amine solution more suitable for carbon capture of automobile exhaust in this system. In addition, the solution still has an extremely high CO2 absorption rate when the CO2 concentration is low. Since the system only uses diesel and ammonia mixed combustion during cold start, the proportion of diesel is low and the generated CO2 concentration is also low. The use of this carbon capture device can effectively achieve the decarbonization effect.

[0050] A diesel flow electronically controlled valve 6 is provided on the pipeline between the outlet of the diesel tank 5 and the intake passage of the dual-fuel engine 7. The diesel flow electronically controlled valve 6 is used to control the supply amount of diesel in the diesel tank 5 or whether to supply it. An air flow electronically controlled valve 4 is provided at the air end of the intake passage of the dual-fuel engine 7. The air flow electronically controlled valve 4 is used to control the supply amount of air.

[0051] The catalytic cracking reactor 8 also includes an electric heater, which is located inside the catalytic cracking reaction flow channel, and the electric heater assists in heating the catalytic cracking reaction flow channel; the ammonia cracking catalyst is distributed in the catalytic cracking reaction flow channel of the catalytic cracking reactor 8, and the electric heater is arranged close to the catalytic cracking reaction flow channel, and the exhaust gas waste heat recovery part transports the heat exchange with the exhaust gas to the outside of the catalytic cracking reaction flow channel, and the exhaust gas waste heat recovery part and the electric heater jointly provide heat for the catalytic cracking reaction flow channel. An electric heating layer is wrapped around the outside of the adsorption ammonia storage tank 11, and the electric heating layer is used to preheat the adsorption ammonia storage tank 11.

[0052] The liquid ammonia tank 1 of the present application is used to provide ammonia, the diesel tank 5 is used to provide diesel, the catalytic cracking reactor 8 is used to exchange heat with the exhaust gas and catalyze the cracking of ammonia to produce hydrogen, the adsorption ammonia storage tank 11 is used to supplement ammonia for the SCR reactor, the SCR reactor 13 is used to denitrify the exhaust gas, the electronically controlled nozzle 16 and the electronically controlled nozzle 2 17 are used to cool the exhaust gas, the liquid storage tank 18 is used to collect liquid water sprayed by the electronically controlled nozzle, and the carbon capture device 19 is used to absorb a small amount of CO2 in the exhaust gas.

[0053] The near-zero carbon emission engine based on catalytic cracking hydrogen production and dual-mode mixed combustion and the dual-fuel engine in the exhaust gas after-treatment system of the present application can burn ammonia, diesel mixture and ammonia, hydrogen mixture respectively under the two working conditions of cold start and stable operation, so as to realize the normal operation of the vehicle during the cold start of the engine and shorten the warm-up time, wherein the hydrogen is obtained by catalytic cracking of part of the ammonia in the intake air. The system is also provided with an exhaust gas after-treatment device, which uses the waste heat of the exhaust gas to drive the adsorption ammonia storage tank, and obtains high-purity ammonia through thermochemical adsorption / desorption technology for removing NOx pollutants in the exhaust gas in the SCR reactor. In the stable operation mode, the exhaust gas discharged by the SCR can be directly discharged into the atmosphere; in the cold start mode, the exhaust gas flows through the carbon capture passage, and after being cooled by water working fluid spray and absorbing excess NH3, it flows into the carbon capture device for decarbonization process, and finally achieves the effect of near-zero carbon and zero pollution emissions of the system.

[0054] A working method of a near-zero carbon emission engine system, specifically comprising:

[0055] When the dual-fuel engine 7 is cold-started, the second ammonia flow electronically controlled valve 3, the air flow electronically controlled valve 4, the diesel flow electronically controlled valve 6, the first exhaust gas flow electronically controlled valve 9, the second exhaust gas flow electronically controlled valve 10, the third ammonia flow electronically controlled valve 12, and the fourth exhaust gas flow electronically controlled valve 15 are opened, and the first ammonia flow electronically controlled valve 2 and the third exhaust gas flow electronically controlled valve 14 are closed, and the dual-fuel engine 7 burns ammonia and diesel mixed fuel;

[0056] The two fuels are fully premixed with the air in the intake duct and then enter the dual-fuel engine 7 for combustion. The high-temperature exhaust gas after combustion in the cylinder enters the exhaust gas waste heat recovery part of the catalytic cracking reactor 8 to fully exchange heat with the catalytic cracking reaction flow channel. At the same time, the electric heater performs auxiliary heating on the catalytic cracking reaction flow channel. Under the combined action of the high-temperature exhaust gas and the electric heater, the catalytic cracking reaction flow channel is rapidly heated.

[0057] The adsorption ammonia storage tank 11 has been heated in advance by the surface electric heating layer. After being heated, the pressure of the adsorption ammonia storage tank 11 increases to the desorption pressure and releases a certain amount of ammonia. The first tail gas flow electronically controlled valve 9 controls the temperature and pressure in the adsorption ammonia storage tank 11 by adjusting the tail gas flow entering the adsorption ammonia storage tank 11. The third ammonia flow electronically controlled valve 12 adjusts the ammonia flow entering the SCR reactor 13 to reduce ammonia consumption; after the tail gas flows out of the catalytic cracking reactor 8, part of it flows into the adsorption ammonia storage tank 11 to heat it. At this time, the adsorption ammonia storage tank 11 is driven by the heat of the tail gas; the ammonia enters the SCR reactor 13, and the tail gas flowing through the first tail gas flow electronically controlled valve 9 and the second tail gas flow electronically controlled valve 10 merges at the outlet of the adsorption ammonia storage tank 11, and flows into the SCR reactor 13 to react chemically with the ammonia desorbed from the adsorption ammonia storage tank 11 to achieve denitrification of the tail gas;

[0058] The tail gas after denitrification flows out of the SCR reactor 13 and flows through the fourth tail gas flow electric control valve 15. The liquid water sprayed by the electric control nozzle reduces the tail gas temperature to below 65°C. The tail gas after cooling enters the carbon capture device for decarbonization treatment. The tail gas flowing out of the carbon capture device is discharged into the atmosphere.

[0059] When the dual-fuel engine 7 is running stably, the temperature in the catalytic cracking reaction flow channel of the catalytic cracking reactor 8 should reach above 450°C. At this time, the first ammonia flow electronically controlled valve 2, the second ammonia flow electronically controlled valve 3, the air flow electronically controlled valve 4, the first tail gas flow electronically controlled valve 9, the second tail gas flow electronically controlled valve 10, the third ammonia flow electronically controlled valve 12 and the third tail gas flow electronically controlled valve 14 are opened, and the diesel flow electronically controlled valve 6 and the fourth tail gas flow electronically controlled valve 15 are closed. Part of the ammonia flowing out of the liquid ammonia tank 1 enters the catalytic cracking reaction flow channel of the catalytic cracking reactor 8 through the first ammonia flow electronically controlled valve 2. Ammonia is cracked into hydrogen and nitrogen under the combined action of the ruthenium-based catalyst and the high-temperature environment to form a hydrogen-rich gas flow. The hydrogen-rich gas flows out from the catalytic cracking reaction flow channel outlet of the catalytic cracking reactor 8 and flows into the engine intake pipe. After being fully premixed with the ammonia and air in the intake pipe, it enters the dual-fuel engine 7 for combustion; the dual-fuel engine 7 burns ammonia and hydrogen mixed fuel;

[0060] The high-temperature exhaust gas after combustion in the cylinder enters the exhaust gas waste heat recovery part of the catalytic cracking reactor 8 to fully exchange heat with the catalytic cracking reaction flow channel. At the same time, the electric heater assists in heating the catalyst layer to ensure that the temperature of the catalytic cracking reaction flow channel is always maintained above 450°C; after the exhaust gas flows out of the catalytic cracking reactor 8, part of it flows into the adsorption ammonia storage tank 11 to be heated, and the exhaust gas flowing through the first exhaust gas flow electronically controlled valve 9 and the second exhaust gas flow electronically controlled valve 10 converges at the outlet of the adsorption ammonia storage tank 11, and flows into the SCR reactor 13 to chemically react with the ammonia desorbed from the adsorption ammonia storage tank 11 to achieve denitrification of the exhaust gas. Since the ammonia-hydrogen mixed combustion product does not contain carbon dioxide, the exhaust gas flowing out of the SCR reactor 13 is directly discharged after passing through the third exhaust gas flow electronically controlled valve 14.

[0061] The embodiments of the invention disclosed above are only used to help illustrate the invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the invention, so that those skilled in the art can understand and use the invention well.

Claims

1. A near-zero carbon emission engine system, characterized in that: It comprises a liquid ammonia tank (1), a diesel tank (5), a dual-fuel engine (7), a catalytic cracking reactor (8), an adsorption-type solid ammonia storage NOx removal device and a decarbonization device; The liquid ammonia tank (1) and the diesel tank (5) are each connected to the air intake of the dual-fuel engine (7) through a pipeline, the air intake is connected to the outside atmosphere, the outlet of the liquid ammonia tank (1) is connected to the reaction channel inlet of the catalytic cracking reactor (8) through a pipeline, the reaction channel outlet of the catalytic cracking reactor (8) is connected to the air intake of the dual-fuel engine (7), the tail gas outlet of the dual-fuel engine (7) is connected to the tail gas waste heat recovery inlet of the catalytic cracking reactor (8), the tail gas waste heat recovery outlet during the catalytic cracking reaction period is connected to the adsorption type solid ammonia storage and NOx removal device, the adsorption type solid ammonia storage and NOx removal device is connected to the atmosphere through the tail gas purification pipeline, the adsorption type solid ammonia storage and NOx removal device is connected to the inlet of the decarbonization device, and the outlet of the decarbonization device is connected to the tail gas purification pipeline; A first ammonia flow rate electric control valve (2) is provided on the pipeline between the outlet of the liquid ammonia tank (1) and the inlet of the reaction flow channel of the catalytic cracking reactor (8), a second ammonia flow rate electric control valve (3) is provided on the pipeline connecting the outlet of the liquid ammonia tank (1) and the intake channel of the dual-fuel engine (7), a third tail gas flow rate electric control valve (14) is provided on the tail gas purification pipeline, and a fourth tail gas flow rate electric control valve (15) is provided on the pipeline connecting the adsorption solid ammonia storage NOx removal device and the inlet of the decarbonization device; The catalytic cracking reactor (8) is used for exchanging heat with the tail gas and catalyzing ammonia cracking to produce hydrogen, the adsorption-type solid ammonia storage and NOx removal device is used for denitrifying the tail gas, and the decarbonization device is used for decarbonizing the tail gas; The adsorption-type solid ammonia storage NOx removal device comprises an adsorption-type ammonia storage tank (11) and an SCR reactor (13); the exhaust gas waste heat recovery outlet of the catalytic cracking reactor (8) is respectively connected to the air inlet of the adsorption-type ammonia storage tank (11) and the air inlet of the SCR reactor (13) through pipelines; the air outlet of the adsorption-type ammonia storage tank (11) is connected to the air inlet of the SCR reactor (13) through a pipeline; the air outlet of the SCR reactor (13) is respectively connected to the exhaust gas purification pipeline and the decarbonization device; and the ammonia outlet of the adsorption-type ammonia storage tank (11) is connected to the reducing agent inlet of the SCR reactor (13) through an ammonia pipeline; A first tail gas flow electric control valve (9) is provided on the pipeline between the tail gas waste heat recovery outlet of the catalytic cracking reactor (8) and the air inlet of the adsorption ammonia storage tank (11), a second tail gas flow electric control valve (10) is provided on the pipeline between the tail gas waste heat recovery outlet of the catalytic cracking reactor (8) and the air inlet of the SCR reactor (13), and a third ammonia flow electric control valve (12) is provided on the ammonia pipeline; The decarbonization device comprises an electrically controlled nozzle, a liquid storage tank (18) and a carbon capture device; the gas outlet of the SCR reactor (13) is connected to the liquid inlet of the liquid storage tank (18) and the gas inlet of the carbon capture device through a spray pipeline, the electrically controlled nozzle is arranged on the spray pipeline, the gas outlet of the carbon capture device is connected to the purification pipeline, and a fourth tail gas flow electrically controlled valve (15) is arranged on the spray pipeline near the gas outlet of the SCR reactor (13).

2. A near-zero carbon emission engine system according to claim 1, characterized in that: Two electrically controlled nozzles are provided, namely electrically controlled nozzle 1 (16) and electrically controlled nozzle 2 (17).

3. A near-zero carbon emission engine system according to claim 1, characterized in that: The carbon capture device is provided with a quaternary mixed amine solution which is a mixture of MEA, DMAE, TEA and PZ in a certain proportion.

4. A near-zero carbon emission engine system according to claim 3, characterized in that: The molar ratio of each substance in the quaternary mixed amine solution is MEA:DMAE:TEA:PZ=4:4:2:

1.

5. The near-zero carbon emission engine system according to claim 1, characterized in that: A diesel flow electric control valve (6) is provided on a pipeline between the outlet of the diesel tank (5) and the air intake passage of the dual-fuel engine (7).

6. A near-zero carbon emission engine system according to claim 1, characterized in that: An air flow electric control valve (4) is provided at the air end of the air intake passage of the dual-fuel engine (7).

7. A near-zero carbon emission engine system according to claim 1, characterized in that: The catalytic cracking reactor (8) further comprises an electric heater, which is located inside the catalytic cracking reaction flow channel and performs auxiliary heating on the catalytic cracking reaction flow channel; an electric heating layer is wrapped around the outside of the adsorption ammonia storage tank (11) and is used to preheat the adsorption ammonia storage tank (11).

8. The method for operating a near-zero carbon emission engine system according to claim 7, characterized in that: Specifically include: When the dual-fuel engine (7) is cold-started, the second ammonia flow electronically controlled valve (3), the air flow electronically controlled valve (4), the diesel flow electronically controlled valve (6), the first exhaust gas flow electronically controlled valve (9), the second exhaust gas flow electronically controlled valve (10), the third ammonia flow electronically controlled valve (12), and the fourth exhaust gas flow electronically controlled valve (15) are opened, and the first ammonia flow electronically controlled valve (2) and the third exhaust gas flow electronically controlled valve (14) are closed, and the dual-fuel engine (7) burns a mixed fuel of ammonia and diesel; The two fuels are fully premixed with air in the intake duct and then enter the dual-fuel engine (7) for combustion. The high-temperature exhaust gas after combustion in the cylinder enters the exhaust gas waste heat recovery part of the catalytic cracking reactor (8) for full heat exchange with the catalytic cracking reaction flow channel. At the same time, the electric heater performs auxiliary heating on the catalytic cracking reaction flow channel. Under the combined action of the high-temperature exhaust gas and the electric heater, the catalytic cracking reaction flow channel is rapidly heated. The tail gas flows out of the catalytic cracking reactor (8) and enters the adsorption type solid ammonia storage NOx removal device for tail gas denitrification. The tail gas after denitrification is decarbonized by the decarbonization device and then discharged into the atmosphere. When the dual-fuel engine is running stably, the temperature in the catalytic cracking reaction flow channel of the catalytic cracking reactor (8) should reach a certain temperature or above. At this time, the first ammonia flow electronically controlled valve (2), the second ammonia flow electronically controlled valve (3), the air flow electronically controlled valve (4), the first tail gas flow electronically controlled valve (9), the second tail gas flow electronically controlled valve (10), the third ammonia flow electronically controlled valve (12) and the third tail gas flow electronically controlled valve (14) are opened, the diesel flow electronically controlled valve (6) and the fourth tail gas flow electronically controlled valve (15) are closed, and part of the ammonia flowing out of the liquid ammonia tank (1) enters the catalytic cracking reaction flow channel of the catalytic cracking reactor (8) through the first ammonia flow electronically controlled valve (2), and the ammonia is cracked into hydrogen and nitrogen. The hydrogen and nitrogen flows out from the outlet of the catalytic cracking reaction flow channel of the catalytic cracking reactor (8) and flows into the engine intake pipe, and enters the dual-fuel engine (7) for combustion after being fully premixed with the ammonia and air in the intake pipe; the dual-fuel engine (7) burns the ammonia-hydrogen mixed fuel; The high-temperature exhaust gas after combustion in the cylinder enters the exhaust gas waste heat recovery part of the catalytic cracking reactor (8) to fully exchange heat with the catalytic cracking reaction flow channel. After the exhaust gas flows out of the catalytic cracking reactor (8), it enters the adsorption-type solid ammonia storage NOx removal device for exhaust gas denitrification. The purified exhaust gas is discharged into the atmosphere through the purified exhaust gas pipeline.

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