Method of operating an ammonia engine aftertreatment device with water spray and ammonia recovery system

Abstract

This invention provides a method for operating an aftertreatment device for an ammonia engine with a water spray and ammonia recovery system, comprising: an exhaust piping system, a spray water system, a heat exchange medium system, an ammonia recovery system, and an emission detection system; a selective catalytic reduction unit, a heat exchanger, and a water spray chamber are sequentially connected and placed downstream of the ammonia engine to form the exhaust piping system; the heat exchanger is connected to an ammonia separation chamber to form the heat exchange medium system; the water spray chamber is located within the spray water system; the ammonia separation chamber is connected to the water spray chamber and utilizes the waste heat from the ammonia engine exhaust gas through the heat exchange medium system; the ammonia recovery system is connected to the ammonia separation chamber; and an emission detection system is installed on the exhaust piping system. This invention, through the emission detection system, can control the amount of water sprayed in the water spray chamber in real time according to changes in unburned ammonia and NOx emissions, achieving simultaneous purification of NOx and unburned ammonia, while eliminating the need for an additional reducing agent injection system and avoiding the waste of unburned ammonia and the generation of byproducts such as N2O.

Description

Technical Field

[0001] This invention relates to the field of engine exhaust gas treatment, and more specifically, to a method for operating an ammonia engine aftertreatment device with a water spray and ammonia recovery system. Background Technology

[0002] Unburned ammonia in the exhaust of ammonia-fueled engines can be directly used as a reducing agent for the SCR reaction, eliminating the need for additional reducing agent storage, supply, and injection systems. However, ammonia fuel has poor combustion characteristics, resulting in an excess of unburned ammonia in the exhaust compared to NOx. This still requires an ammonia oxidation catalytic converter (ASC) to treat the excess unburned ammonia, which also leads to fuel waste and the generation of byproducts such as N2O.

[0003] In the existing technology, patent document CN114856764A discloses an exhaust gas treatment system, engine, and ship for an ammonia fuel engine, which can be applied to the field of exhaust gas treatment technology. The system of this invention removes water from the engine exhaust gas through a first dehydration device. A nitrogen oxide (NOx) trap reacts the dehydrated exhaust gas with hydrogen to generate a small amount of ammonia. A portion of the exhaust gas output from the NOx trap is collected through a pipeline, and the waste heat of the exhaust gas is used to provide heat to an ammonia synthesis device, enabling the synthesis of ammonia. The remaining exhaust gas and ammonia are output to a heat exchanger, where a denitrification device reduces the exhaust gas and ammonia to nitrogen and water. A liquid nitrogen heat exchanger separates the non-condensable gases and collects the ammonia. Then, nitrous oxide and water are removed through a water tank and a second dehydration device. Finally, a nitrogen separation device separates nitrogen and oxygen, thereby achieving ammonia collection and waste gas recovery. Patent document CN217206623U discloses an aftertreatment device for exhaust gas from a hydrogen-ammonia fuel engine, including an exhaust catalytic converter and an ammonia supply device. The exhaust catalytic converter converts ammonia (NH3) and nitrogen oxides (NOx) in the exhaust gas, and the ammonia supply device supplies ammonia (NH3) to the exhaust catalytic converter. The exhaust catalytic converter includes a first SCR catalyst, a first exhaust pipe, a second SCR catalyst, a second exhaust pipe, and an ammonia escape catalyst (ASC) connected in sequence. The inlet of the first SCR catalyst is connected to the exhaust outlet of the hydrogen-ammonia fuel engine, and the end of the ammonia supply device is installed on the first exhaust pipe. Currently available exhaust gas treatment devices are complex in structure and still require an ammonia oxidation catalyst (ASC) to treat excess unburned ammonia, failing to address issues such as fuel waste and the generation of byproducts like N2O. Furthermore, patent document CN114856764A requires an additional hydrogen supply system and does not provide a solution for treating the collected ammonia water. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for operating an ammonia engine aftertreatment device with a water spraying and ammonia recovery system.

[0005] The operating method of an ammonia engine aftertreatment device with a water spraying and ammonia recovery system provided by the present invention includes: an exhaust pipeline system, a spraying water system, a heat exchange working fluid system, an ammonia recovery system, and an emission detection system;

[0006] The selective catalytic reduction unit, heat exchanger, and water spray chamber are sequentially connected and placed after the ammonia engine to form the exhaust piping system;

[0007] The heat exchanger is connected to the ammonia separation chamber and forms a heat exchange working fluid system. The water spray chamber is set in the spray water system. The ammonia separation chamber is connected to the water spray chamber and utilizes the waste heat of the ammonia engine exhaust gas through the heat exchange working fluid system. The ammonia recovery system is connected to the ammonia separation chamber. The emission detection system is set on the exhaust pipeline system.

[0008] Preferably, the operation method of the emission detection system is as follows:

[0009] The controller acquires signals from the first NOx sensor and the first ammonia sensor to obtain the original emissions of NOx and unburned ammonia in the ammonia engine, and the controller acquires signals from the second NOx sensor to obtain the NOx content after the SCR reaction in the selective catalytic reduction unit;

[0010] The controller acquires the signal from the second ammonia sensor to obtain the content of unburned ammonia after the SCR (Selective Catalytic Reduction) reaction in the selective catalytic reducer and the condensation and dehydration process in the heat exchanger;

[0011] The controller controls the spray pulse width and spray pressure of the water sprayer in real time based on the measurement value of the second ammonia sensor to control the water spray volume.

[0012] The controller collects signals from the third NOx sensor and the third ammonia sensor and confirms whether the final emissions meet the standards.

[0013] Preferably, the heat exchanger outlet is connected to the heat exchanger inlet of the ammonia separation chamber, the heat exchanger outlet of the ammonia separation chamber is connected to the heat exchanger inlet of the heat exchanger, and a circulating heat exchanger is provided in the heat exchanger system formed between the heat exchanger and the ammonia separation chamber.

[0014] Preferably, a water sprayer is installed on the water spray chamber and water is sprayed into the water spray chamber through the water sprayer; the water spray chamber is connected to the ammonia separation chamber, and the ammonia separation chamber is connected to the water sprayer.

[0015] The spray water system is configured such that: the ammonia water in the spray chamber flows to the ammonia separation chamber where it is heated and ammonia gas is separated; the water in the ammonia separation chamber flows to the water sprayer and sprays water into the spray chamber again.

[0016] Preferably, the ammonia recovery system consists of the ammonia fuel tank connected to the ammonia separation chamber.

[0017] Preferably, the emission detection system includes: a NOx sensor, an ammonia sensor, and a controller;

[0018] The NOx sensor and the ammonia sensor are installed on the exhaust piping system and are connected to the controller.

[0019] Preferably, the NOx sensor includes: a first NOx sensor, a second NOx sensor, and a third NOx sensor;

[0020] The first NOx sensor is installed between the ammonia engine and the selective catalytic reduction unit, the second NOx sensor is installed between the selective catalytic reduction unit and the heat exchanger, and the third NOx sensor is installed at the end of the water spray chamber away from the ammonia engine.

[0021] Preferably, the ammonia sensor includes: a first ammonia sensor, a second ammonia sensor, and a third ammonia sensor;

[0022] The first ammonia sensor is installed between the ammonia engine and the selective catalytic reduction unit, the second ammonia sensor is installed between the heat exchanger and the water spray chamber, and the third ammonia sensor is installed at the end of the water spray chamber away from the ammonia engine.

[0023] Preferably, the controller is connected to the water sprayer.

[0024] Preferably, the spray direction of the water sprayer is opposite to, the same as, or perpendicular to the exhaust emission direction of the ammonia engine.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention uses an emission detection system to control the amount of water sprayed in the water spray chamber in real time according to the changes in unburned ammonia and NOx emissions under different operating conditions of the ammonia engine, so as to achieve simultaneous purification of NOx and unburned ammonia. At the same time, it eliminates the need for an additional reducing agent injection system and avoids the waste of unburned ammonia and the generation of by-products such as N2O in the traditional ammonia oxidation catalyst scheme.

[0027] 2. In this invention, NOx is first reduced by unburned ammonia in the exhaust gas in a selective catalytic reduction unit. Then, water is sprayed in the water spray chamber to adsorb the excess unburned ammonia. Finally, ammonia is separated from the ammonia solution in the ammonia separation chamber using the waste heat of the exhaust gas and then supplied to the engine. Attached Figure Description

[0028] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0029] Figure 1 This is a schematic diagram of an ammonia engine aftertreatment device.

[0030] As shown in the figure:

[0031] Detailed Implementation

[0032] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0033] like Figure 1 As shown, this embodiment includes: an ammonia fuel tank 2, a selective catalytic reduction unit 3, a heat exchanger 4, an ammonia separation chamber 5, a water spray chamber 6, a water sprayer 7, a NOx sensor 8, an ammonia sensor 9, and a controller 10.

[0034] Ammonia fuel tank 2: A collection device used after unburned ammonia is separated in ammonia separation chamber 5.

[0035] Selective catalytic reducer 3: A device that uses excess unburned ammonia to reduce NOx.

[0036] Heat exchanger 4: A device for recovering waste heat and condensing water from the mixed gas after the SCR reaction through a heat exchange working fluid system.

[0037] Ammonia Separation Chamber 5: A device that separates ammonia gas and water by heating ammonia water through a heat exchange working fluid system.

[0038] Water sprayer 7 and water spray chamber 6: devices for water mist spraying and ammonia water collection, where excess unburned ammonia dissolves in water in water spray chamber 6.

[0039] NOx Sensor 8: A device for detecting NOx content.

[0040] Ammonia Sensor 9: A device for detecting the content of unburned ammonia.

[0041] Controller 10: A device for adjusting the spray parameters of water sprayer 7 based on data fed back from NOx sensor 8 and ammonia sensor 9.

[0042] Specifically, the selective catalytic reduction unit 3, the heat exchanger 4, and the water spray chamber 6 are sequentially connected and placed after the ammonia engine 1 to form an exhaust pipeline system; the heat exchanger 4 is connected to the ammonia separation chamber 5 and forms a heat exchange working fluid system; the water spray chamber 6 is set in the spray water system; the ammonia separation chamber 5 is connected to the water spray chamber 6 and utilizes the waste heat of the ammonia engine 1 exhaust gas through the heat exchange working fluid system; the ammonia recovery system is connected to the ammonia separation chamber 5; and an emission detection system is installed on the exhaust pipeline system.

[0043] The heat exchanger 4 has its heat exchange medium outlet connected to the heat exchange medium inlet of the ammonia separation chamber 5, and the heat exchange medium outlet of the ammonia separation chamber 5 is connected to the heat exchange medium inlet of the heat exchanger 4. A circulating heat exchange medium is installed in the heat exchange medium system formed between the heat exchanger 4 and the ammonia separation chamber 5.

[0044] A water sprayer 7 is installed on the water spray chamber 6, and water is sprayed into the water spray chamber 6 through the water sprayer 7. The water spray chamber 6 is connected to the ammonia separation chamber 5, and the ammonia separation chamber 5 is connected to the water sprayer 7. The spray water system is configured such that the ammonia water in the water spray chamber 6 flows to the ammonia separation chamber 5 and is heated, and the water in the ammonia separation chamber 5 flows to the water sprayer 7 and sprays water into the water spray chamber 6 again. The spray direction of the water sprayer 7 is opposite to, the same as, or perpendicular to the exhaust gas emission direction of the ammonia engine 1.

[0045] The ammonia recovery system consists of an ammonia fuel tank 2 connected to an ammonia separation chamber 5.

[0046] The emission detection system includes: a NOx sensor 8, an ammonia sensor 9, and a controller 10. The NOx sensor 8 and ammonia sensor 9 are installed on the exhaust piping system, and the NOx sensor 8, ammonia sensor 9, and water sprayer 7 are connected to the controller 10. The NOx sensor 8 includes: a first NOx sensor 801, a second NOx sensor 802, and a third NOx sensor 803. The first NOx sensor 801 is installed between the ammonia engine 1 and the selective catalytic reduction unit 3; the second NOx sensor 802 is installed between the selective catalytic reduction unit 3 and the heat exchanger 4; and the third NOx sensor 803 is installed at the end of the water spray chamber 6 furthest from the ammonia engine 1. The ammonia sensor 9 includes: a first ammonia sensor 901, a second ammonia sensor 902, and a third ammonia sensor 903. The first ammonia sensor 901 is installed between the ammonia engine 1 and the selective catalytic reduction unit 3; the second ammonia sensor 902 is installed between the heat exchanger 4 and the water spray chamber 6; and the third ammonia sensor 903 is installed at the end of the water spray chamber 6 furthest from the ammonia engine 1.

[0047] Working principle:

[0048] First, excess unburned ammonia and NOx in the exhaust gas from the ammonia engine 1 react in the selective catalytic reduction unit 3. The reacted exhaust gas then provides heat to the heat exchange system in the heat exchanger 4 and condenses to remove water. Water sprayer 7 sprays water mist, and excess unburned ammonia dissolves in the water flow in the water spray chamber 6 to form ammonia water. The ammonia water in the water spray chamber 6 enters the ammonia separation chamber 5. Then, the unburned ammonia dissolved in the ammonia water in the ammonia separation chamber 5 is heated and separated by the heat exchange system. The separated unburned ammonia is collected in the ammonia fuel tank 2. The separated water in the ammonia separation chamber 5 flows back to the water sprayer 7 and is sprayed back into the water spray chamber 6, forming the spray water system.

[0049] The controller 10 acquires signals from the first NOx sensor 801 and the first ammonia sensor 901 to obtain the original emissions of NOx and unburned ammonia in the ammonia engine 1, and acquires signals from the second NOx sensor 802 to determine whether there is any NOx residue after the SCR reaction in the selective catalytic reduction unit 3. The controller 10 acquires signals from the second ammonia sensor 902 to obtain the content of unburned ammonia after the SCR reaction in the selective catalytic reduction unit 3 and the condensation and dehydration process in the heat exchanger 4. Based on the measurement value of the second ammonia sensor 902, the controller 10 controls the spray pulse width and spray pressure of the water sprayer 7 in real time to control the water spray volume in order to collect as much unburned ammonia as possible. Finally, the controller 10 acquires signals from the third NOx sensor 803 and the third ammonia sensor 903 to confirm whether the final emissions meet the standards.

[0050] Example 2

[0051] Example 2 is a preferred example of Example 1.

[0052] like Figure 1 As shown, this embodiment includes: an ammonia engine 1, an ammonia fuel tank 2, a selective catalytic reduction unit 3, a heat exchanger 4, an ammonia separation chamber 5, a water spray chamber 6, a water sprayer 7, a NOx sensor 8, an ammonia sensor 9, and a controller 10.

[0053] Selective catalytic reduction unit 3, heat exchanger 4, and water spray chamber 6 are connected in sequence and placed after ammonia engine 1 to form exhaust pipeline system.

[0054] In one embodiment, a water sprayer 7 is installed on the upper part of the water spray chamber 6 to spray water and adsorb excess unburned ammonia. The lower right side of the ammonia separation chamber 5 is connected to the drain outlet at the bottom of the water spray chamber 6 and the heat exchanger 4, and the lower left side is provided with a water outlet connected to the water sprayer 7, thus forming a spray water system. The spray direction of the water sprayer 7 can be opposite to, the same as, or perpendicular to the exhaust gas direction.

[0055] The heat exchanger 4 is provided with a heat exchange medium inlet and outlet at the bottom, which are sequentially connected to the heat exchange medium outlet and inlet at the top of the ammonia separation chamber 5 to form a heat exchange medium system; in one embodiment, the heat exchange medium includes water, heat exchange oil or ethylene glycol.

[0056] An ammonia outlet is located on the upper left side of the ammonia separation chamber 5, which is connected to the ammonia fuel tank 2 to form an ammonia recovery system.

[0057] A first NOx sensor 801 and a first ammonia sensor 901 are installed between the ammonia engine 1 and the selective catalytic reducer 3. A second NOx sensor 802 is installed between the selective catalytic reducer 3 and the heat exchanger 4. A second ammonia sensor 902 is installed between the heat exchanger 4 and the water spray chamber 6. A third NOx sensor 803 and a third ammonia sensor 903 are installed at the exhaust outlet of the water spray chamber 6. All of the above sensors are connected to the controller 10 to form an emission detection system.

[0058] The operation of an emissions detection system includes the following steps:

[0059] Step S1: The controller 10 collects signals from the first NOx sensor 801 and the first ammonia sensor 901 to obtain the raw emissions of the ammonia engine 1, and collects signals from the second NOx sensor 802 to obtain the NOx content after the SCR reaction in the selective catalytic reduction unit 3, and confirms whether there is any NOx residue.

[0060] Step S2: Acquire the signal from the second ammonia sensor 902 to obtain the content of unburned ammonia after the SCR reaction in the selective catalytic reduction unit 3 and the dehydration process in the heat exchanger 4; Based on the measurement value of the second ammonia sensor 902, control the spray pulse width and spray pressure of the water sprayer 7 in real time to control the water spray volume.

[0061] Step S3: Collect data from the third NOx sensor 803 and the third ammonia sensor 903 to confirm whether the final emissions meet the standards.

[0062] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0063] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for operating an ammonia engine aftertreatment device with a water spraying and ammonia recovery system, characterized in that, include: Exhaust piping system, spray water system, heat exchange medium system, ammonia recovery system, and emission detection system; The selective catalytic reduction unit (3), the heat exchanger (4), and the water spray chamber (6) are connected in sequence and placed after the ammonia engine (1) to form an exhaust pipeline system; The heat exchanger (4) is connected to the ammonia separation chamber (5) and constitutes a heat exchange working fluid system. The water spray chamber (6) is set in the spray water system. The ammonia separation chamber (5) is connected to the water spray chamber (6) and utilizes the waste heat of the exhaust gas of the ammonia engine (1) through the heat exchange working fluid system. The ammonia recovery system is connected to the ammonia separation chamber (5). The exhaust pipeline system is equipped with the emission detection system. A water sprayer (7) is installed on the water spray chamber (6) and water is sprayed into the water spray chamber (6) through the water sprayer (7). The water spray chamber (6) is connected to the ammonia separation chamber (5), and the ammonia separation chamber (5) is connected to the water sprayer (7). The spray water system is configured such that: the ammonia water in the water spray chamber (6) flows to the ammonia separation chamber (5) and is heated; the water in the ammonia separation chamber (5) flows to the water sprayer (7) and sprays water into the water spray chamber (6) again; The ammonia recovery system consists of an ammonia fuel tank (2) connected to the ammonia separation chamber (5); The emission detection system includes: a NOx sensor (8), an ammonia sensor (9), and a controller (10); The NOx sensor (8) and the ammonia sensor (9) are installed on the exhaust pipeline system and are connected to the controller (10). The NOx sensor (8) includes: a first NOx sensor (801), a second NOx sensor (802), and a third NOx sensor (803); The first NOx sensor (801) is installed between the ammonia engine (1) and the selective catalytic reducer (3), the second NOx sensor (802) is installed between the selective catalytic reducer (3) and the heat exchanger (4), and the third NOx sensor (803) is installed at the end of the water spray chamber (6) away from the ammonia engine (1). The ammonia sensor (9) includes: a first ammonia sensor (901), a second ammonia sensor (902), and a third ammonia sensor (903). The first ammonia sensor (901) is installed between the ammonia engine (1) and the selective catalytic reducer (3), the second ammonia sensor (902) is installed between the heat exchanger (4) and the water spray chamber (6), and the third ammonia sensor (903) is installed at the end of the water spray chamber (6) away from the ammonia engine (1). The operating method of the ammonia engine aftertreatment device with water spraying and ammonia recovery system includes the following steps: In step S1, the unburned ammonia and NOx in the exhaust gas of the ammonia engine (1) react through the selective catalytic reduction device (3), and the exhaust gas after reaction provides heat to the heat exchange working fluid system in the heat exchanger (4) and condenses to remove water. In step S2, the water sprayer (7) sprays water, and excess unburned ammonia dissolves in water mist in the water spray chamber (6) to form ammonia water. The ammonia water in the water spray chamber (6) enters the ammonia separation chamber (5). In step S3, the ammonia water in the ammonia separation chamber (5) is heated by the heat exchange working fluid system and ammonia gas is separated. The unburned ammonia after separation is collected by the ammonia fuel tank (2). In step S4, the water separated in the ammonia separation chamber (5) flows to the water sprayer (7) and is sprayed back into the water spray chamber (6) to form a spray water system. Step S5, the controller (10) collects the signals from the first NOx sensor (801) and the first ammonia sensor (901) to obtain the original emissions of NOx and unburned ammonia in the ammonia engine (1), and the controller (10) collects the signal from the second NOx sensor (802) to obtain the NOx content after the SCR reaction in the selective catalytic reduction unit (3); Step S6, the controller (10) acquires the signal from the second ammonia sensor (902) to obtain the content of unburned ammonia after the SCR reaction in the selective catalytic reducer (3) and the condensation and dehydration process in the heat exchanger (4); Step S7, the controller (10) controls the spray pulse width and spray pressure of the water sprayer (7) in real time according to the measurement value of the second ammonia sensor (902) to control the water spray volume; In step S8, the controller (10) collects the signals from the third NOx sensor (803) and the third ammonia sensor (903) and confirms whether the final emission meets the standard.

2. The operating method of the ammonia engine aftertreatment device with water spraying and ammonia recovery system according to claim 1, characterized in that: The heat exchanger (4) has its heat exchange medium outlet connected to the heat exchange medium inlet of the ammonia separation chamber (5), and the heat exchange medium outlet of the ammonia separation chamber (5) is connected to the heat exchange medium inlet of the heat exchanger (4). A circulating heat exchange medium is provided in the heat exchange medium system formed between the heat exchanger (4) and the ammonia separation chamber (5).

3. The operating method of the ammonia engine aftertreatment device with water spraying and ammonia recovery system according to claim 1, characterized in that: The controller (10) is connected to the water sprayer (7).

4. The operating method of the ammonia engine aftertreatment device with water spraying and ammonia recovery system according to claim 1, characterized in that: The spray direction of the water sprayer (7) is opposite to, the same as or perpendicular to the exhaust direction of the ammonia engine (1).

Images