A method for treating exhaust gas from a two-stroke marine diesel engine

Abstract

The present invention discloses a method for treating exhaust gas from a two-stroke marine diesel engine, which relates to the technical field of exhaust gas digestion and purification, and solves the problem of a contradictory relationship between ammonia escape and nitrogen oxide conversion rate in current marine diesel engine exhaust gas treatment technology. The method comprises the following steps: digesting, purifying and denitrifying the diesel engine exhaust gas through a first SCR denitration device to obtain primary treated exhaust gas; detecting the gas type and gas concentration in the primary treated exhaust gas of the diesel engine, and analyzing the detection results; subjecting the primary treated exhaust gas to a secondary denitration treatment through a second SCR denitration device to obtain secondary treated exhaust gas, and detecting and analyzing the secondary treated exhaust gas; inputting the exhaust gas to be treated into a first zeolite adsorption device for adsorption treatment, and determining whether the exhaust gas to be treated is to be discharged based on the adsorption treatment result. The present invention meets the emission requirements of nitrogen oxides while reducing ammonia escape.

Description

Technical Field

[0001] The invention belongs to the technical field of tail gas digestion and purification, and specifically relates to a method for treating tail gas from a two-stroke marine diesel engine. Background Art

[0002] A two-stroke marine diesel engine is a low-speed, heavy-load diesel engine designed specifically for large ocean-going vessels. Its operating principle is to complete a complete combustion cycle, including intake, compression, combustion, and exhaust, with each piston stroke (i.e., two strokes). It features a simple structure, high torque, and high fuel efficiency, and is widely used as the main propulsion power source for container ships, tankers, and bulk carriers. Because its combustion process emits large amounts of nitrogen oxides (NOx), it is often equipped with an exhaust after-treatment system, such as a selective catalytic reduction (SCR) device, to meet marine emission regulations.

[0003] In the existing technology, in order to prevent or reduce the ammonia slip phenomenon that occurs when the urea aqueous solution is injected in the SCR technology, the injection amount of the urea aqueous solution is usually reduced accordingly. This method will lead to a decrease in the conversion efficiency of nitrogen oxides and fail to meet the emission requirements of nitrogen oxides. Although increasing the injection amount of the urea aqueous solution can increase the conversion rate of nitrogen oxides, the risk of ammonia slip also increases accordingly, resulting in secondary pollution. In addition, the excessive urea consumption increases the cost of use. The existing SCR technology has a contradictory relationship in actual operation.

[0004] To this end, the present invention proposes a method for treating exhaust gas from a two-stroke marine diesel engine. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for treating exhaust gas from a two-stroke marine diesel engine to solve the problems raised in the above background technology.

[0006] The technical problems to be solved by the present invention are:

[0007] How to meet nitrogen oxide emission requirements while reducing ammonia slip.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for treating exhaust gas from a two-stroke marine diesel engine is as follows:

[0010] Step S100, obtaining historical exhaust data of the diesel engine, performing digestion, purification and denitrification treatment on the diesel engine exhaust through a first SCR denitrification device to obtain primary treated exhaust gas;

[0011] Step S200, detecting the gas type and gas concentration in the primary treated exhaust gas of the diesel engine, and analyzing the detection results;

[0012] Step S300, obtaining device data of a second SCR denitrification device, passing the primary treated exhaust gas through the second SCR denitrification device for secondary denitrification treatment to obtain secondary treated exhaust gas, and performing detection and analysis on the secondary treated exhaust gas;

[0013] In step S400 , the tail gas to be treated is input into a first zeolite adsorption device for adsorption treatment, and whether the tail gas to be treated is to be discharged is determined based on the adsorption treatment result.

[0014] Furthermore, the historical exhaust gas data includes the historical exhaust gas temperature of the diesel engine, the historical exhaust gas output rate of the diesel engine, and the historical concentration of nitrogen oxides in the exhaust gas of the diesel engine.

[0015] Furthermore, the step S100 includes the following sub-steps:

[0016] Step S101: Obtain the historical diesel engine exhaust temperature CYW, the historical diesel engine exhaust output rate SCS, and the historical nitrogen oxide concentration DYN in the diesel engine exhaust. Convert the historical nitrogen oxide concentration to the nitrogen oxide molar flow rate MRL using the ideal gas formula. The specific formula is as follows:

[0017] MRL=(SCS×DYN×10-6×P) / (R×CYW), where the unit of nitrogen oxide molar flow rate is moles per second; P is the atmospheric pressure, and R is the gas constant;

[0018] In step S102, the molar flow rate of the urea aqueous solution NRS is calculated based on the molar flow rate of nitrogen oxides using the formula, which is as follows:

[0019] NRS=MRL / 2;

[0020] Step S103: Obtain the solution concentration RND, solution density RMD, and solution molar mass RMZ of the urea aqueous solution, and calculate the standard spraying rate PSS of the urea aqueous solution using the formula. The specific formula is as follows:

[0021] PSS=(NRS×RMZ) / (RND×RMD);

[0022] In step S104 , the spraying rate of the urea aqueous solution in the first SCR denitrification device is set to a standard spraying rate, and the exhaust gas of the diesel engine is input into the first SCR denitrification device for denitrification treatment to obtain the primary treated exhaust gas of the diesel engine.

[0023] Furthermore, the step S200 includes the following sub-steps:

[0024] Step S201: If only nitrogen oxides exist in the initially treated exhaust gas and no ammonia exists, the concentration of nitrogen oxides is detected;

[0025] When the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the first SCR denitrification device opens the first valve to input the primary treated exhaust gas into the second SCR denitrification device, and enters step S300;

[0026] When the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, it is determined that the primary treated exhaust gas meets the emission standard, and the third valve is opened to discharge the primary treated exhaust gas;

[0027] Step S202: If only ammonia exists in the initially treated exhaust gas and no nitrogen oxides exist, the ammonia concentration is detected;

[0028] When the ammonia concentration is greater than or equal to the maximum ammonia concentration, the second valve is opened to input the primary treated tail gas into the first zeolite adsorption device, and the process proceeds to step S400;

[0029] When the ammonia concentration is less than the maximum ammonia concentration, it is determined that the primary treated tail gas meets the emission standards, and the third valve is opened to discharge the primary treated tail gas;

[0030] Step S203: If both nitrogen oxides and ammonia exist in the initially treated exhaust gas, the concentrations of nitrogen oxides and ammonia are detected respectively;

[0031] When the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration and the ammonia concentration is less than the maximum ammonia concentration, it is determined that the primary treated exhaust meets the emission standards, and the third valve is opened to discharge the primary treated exhaust;

[0032] When the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, or the ammonia concentration is greater than or equal to the maximum ammonia concentration, the first valve is opened to input the primary treated exhaust gas into the second SCR denitrification device, and step S300 is entered.

[0033] Furthermore, the device data specifically includes a minimum valve opening and a maximum valve opening for inputting ammonia into the second SCR denitration device.

[0034] Furthermore, the step S300 includes the following sub-steps:

[0035] Step S301, obtaining the minimum valve opening XMK and the maximum valve opening DMK of the second SCR denitration device;

[0036] Step S302: Set the minimum nitrogen oxide boundary concentration XBN and the maximum nitrogen oxide boundary concentration DBN, and simultaneously obtain the nitrogen oxide concentration DYN in the primary treated exhaust gas; and calculate the valve opening FMK of the second SCR denitration device through a formula;

[0037] Step S303, recording the primary treated tail gas processed by the second SCR denitration device as secondary treated tail gas;

[0038] When the ammonia concentration in the secondary treated tail gas is less than the maximum ammonia concentration and the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, the secondary treated tail gas is discharged;

[0039] When the ammonia concentration in the secondary treated tail gas is less than the maximum ammonia concentration and the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the secondary treated tail gas is subjected to denitrification treatment again until the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, and then the secondary treated tail gas is discharged;

[0040] When the ammonia concentration in the secondary treated tail gas is greater than or equal to the maximum ammonia concentration and the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, the secondary treated tail gas is input into the first zeolite adsorption device;

[0041] When the ammonia concentration in the secondary treated exhaust gas is greater than or equal to the maximum ammonia concentration, and the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the secondary treated exhaust gas is denitrified again until the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, and the secondary treated exhaust gas is input into the first zeolite adsorption device.

[0042] Furthermore, the formula of the valve opening FMK in step S300 is specifically:

[0043] FMK=XMK, DYN≤XBN;

[0044] FMK=XMK+(DYN-XBN) / (DBN-XBN), XBN<DYN<DBN;

[0045] FMK=DMK, DYN≥DBN.

[0046] Furthermore, the primary treated tail gas and the secondary treated tail gas are combined and recorded as tail gas to be treated.

[0047] Furthermore, the step S400 includes the following sub-steps:

[0048] Step S401: Testing the first zeolite adsorption device. If the ammonia concentration in the first zeolite adsorption device is greater than or equal to the zeolite ammonia concentration threshold, it is determined that the ammonia in the first zeolite adsorption device is not completely desorbed, and the first zeolite adsorption device is heated to a standard desorption temperature range. When the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, heating is stopped, and the adsorption temperature of the first zeolite adsorption device is set to the standard adsorption temperature range.

[0049] If the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, setting the adsorption temperature of the first zeolite adsorption device to the standard adsorption temperature range;

[0050] Step S402: inputting the tail gas to be treated into a first zeolite adsorption device for adsorption.

[0051] Furthermore, the step S400 further includes the following sub-steps:

[0052] Step S403, obtaining the final ammonia concentration of the tail gas to be treated after adsorption is completed, and if the final ammonia concentration is less than or equal to the maximum ammonia concentration, the tail gas to be treated is discharged;

[0053] If the final ammonia concentration is still greater than the maximum ammonia concentration, the exhaust gas to be treated is input into the second zeolite adsorption device. When the exhaust gas to be treated is completely input into the second zeolite adsorption device, the first zeolite adsorption device is closed, and the primary treated exhaust gas from the first SCR denitration device and the secondary treated exhaust gas from the second SCR denitration device are simultaneously input into the second zeolite adsorption device; wherein the final ammonia concentration is the ammonia concentration of the exhaust gas to be treated after the adsorption treatment by the first zeolite adsorption device;

[0054] Step S404, heating the first zeolite adsorption device to a standard desorption temperature range, inputting the ammonia in the first zeolite adsorption device into the ammonia storage device, and closing the first zeolite adsorption device when the ammonia concentration in the first zeolite adsorption device is less than or equal to the minimum ammonia concentration;

[0055] Step S405, detecting the final ammonia concentration in the second zeolite adsorption device, and discharging the tail gas to be treated if the final ammonia concentration is less than or equal to the maximum ammonia concentration;

[0056] If the final ammonia concentration is greater than the maximum ammonia concentration, the above steps are repeated until the final ammonia concentration is less than or equal to the maximum ammonia concentration, and the tail gas to be treated is discharged.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] 1. The present invention first obtains historical exhaust data of the diesel engine, then digests, purifies and denitrates the diesel engine exhaust through a first SCR denitration device to obtain primary treated exhaust gas, detects the gas type and gas concentration in the primary treated exhaust gas of the diesel engine, and analyzes the detection results;

[0059] 2. The present invention also obtains the device data of the second SCR denitrification device, and performs secondary denitrification treatment on the initially treated exhaust gas through the second SCR denitrification device to obtain secondary treated exhaust gas, and performs detection and analysis on the secondary treated exhaust gas. Finally, the exhaust gas to be treated is input into the first zeolite adsorption device for adsorption treatment, and whether the exhaust gas to be treated is discharged is determined based on the adsorption treatment result. The present invention meets the emission requirements of nitrogen oxides while reducing ammonia escape. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0061] Figure 1 is a flow chart of the method of the present invention;

[0062] Figure 2 This is a flow chart of the present invention for treating diesel engine exhaust;

[0063] Figure 3 This is an example diagram of the minimum valve opening in the present invention;

[0064] Figure 4 This is an example diagram of the maximum valve opening in the present invention;

[0065] Figure 5 It is a structural diagram of the computer device in the present invention. DETAILED DESCRIPTION

[0066] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0067] For example 1, please refer to Figures 1-4 As shown, the technical solution provided by the present invention is: a method for treating exhaust gas from a two-stroke marine diesel engine, which is used to denitrate nitrogen oxides in the exhaust gas from the diesel engine and adsorb ammonia involved in the reaction to prevent ammonia from escaping. The method is specifically as follows:

[0068] Step S100, obtaining historical exhaust data of the diesel engine, performing digestion, purification and denitrification treatment on the diesel engine exhaust through a first SCR denitrification device to obtain primary treated exhaust gas;

[0069] Specifically, the historical exhaust data includes the historical exhaust temperature of the diesel engine, the historical exhaust output rate of the diesel engine, and the historical concentration of nitrogen oxides in the diesel engine exhaust;

[0070] It should be specifically noted that diesel engine exhaust includes pollutants such as nitrogen oxides, carbon monoxide, hydrocarbons, and sulfur oxides. The first SCR denitrification device is used to decontaminate nitrogen oxides in diesel engine exhaust. Nitrogen oxides specifically include nitrogen monoxide and nitrogen dioxide.

[0071] Among them, denitrification treatment specifically converts nitrogen oxides into nitrogen and water through ammonia, while reducing the concentration of nitrogen oxides;

[0072] In this embodiment, step S100 includes the following sub-steps:

[0073] Step S101: Obtain the historical diesel engine exhaust temperature CYW, the historical diesel engine exhaust output rate SCS, and the historical nitrogen oxide concentration DYN in the diesel engine exhaust. Convert the historical nitrogen oxide concentration to the nitrogen oxide molar flow rate MRL using the ideal gas formula. The specific formula is as follows:

[0074] MRL=(SCS×DYN×10-6×P) / (R×CYW), where the unit of nitrogen oxide molar flow rate is moles per second;

[0075] Where P is the atmospheric pressure, which is 101 kPa in practice. R is the gas constant, which represents the amount of heat required to raise the temperature of an ideal gas by one kelvin per mole. An ideal gas is a gas that behaves in the absence of intermolecular forces and volume.

[0076] Specifically, the conversion between Kelvin temperature and Celsius is: T (K) = t (℃) + 273.15, where T (K) is Kelvin temperature and t (℃) is Celsius;

[0077] In step S102, the molar flow rate of the urea aqueous solution NRS is calculated based on the molar flow rate of nitrogen oxides using the formula, which is as follows:

[0078] NRS=MRL / 2;

[0079] When the urea aqueous solution is heated, the urea aqueous solution generates ammonia and carbon dioxide through thermal decomposition reaction and hydrolysis reaction;

[0080] Step S103: Obtain the solution concentration RND, solution density RMD, and solution molar mass RMZ of the urea aqueous solution, and calculate the standard spraying rate PSS of the urea aqueous solution using the formula. The specific formula is as follows:

[0081] PSS=(NRS×RMZ) / (RND×RMD), where the unit of urea spraying rate is m³ / s;

[0082] In a specific implementation, the concentration of the urea aqueous solution is 32.5%, the density of the solution is 1090 kg / m³, and the molar mass of the solution is 0.06 kg / mol;

[0083] Step S104, setting the spraying rate of the urea aqueous solution in the first SCR denitrification device to a standard spraying rate, and inputting the diesel engine exhaust gas into the first SCR denitrification device for denitrification treatment to obtain the primary treated exhaust gas of the diesel engine;

[0084] It should be specifically noted that this embodiment only analyzes nitrogen, ammonia, and nitrogen oxides in the primary treated tail gas;

[0085] Step S200, detecting the gas type and gas concentration in the primary treated exhaust gas of the diesel engine, and analyzing the detection results;

[0086] In this embodiment, step S200 includes the following sub-steps:

[0087] Step S201: If only nitrogen oxides exist in the primary treated exhaust gas and no ammonia exists, the concentration of nitrogen oxides is detected; since the primary treated exhaust gas usually contains nitrogen, the nitrogen factor is not considered here;

[0088] When the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the first SCR denitrification device opens the first valve to input the primary treated exhaust gas into the second SCR denitrification device, and enters step S300;

[0089] When the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, it is determined that the primary treated exhaust gas meets the emission standard, and the third valve is opened to discharge the primary treated exhaust gas;

[0090] Among them, the nitrogen, ammonia and nitrogen oxides in the primary treated tail gas are detected by a gas detection device; the nitrogen concentration, ammonia concentration and nitrogen oxide concentration are detected by a gas concentration detection device;

[0091] Specifically, the maximum nitrogen oxide concentration is the nitrogen oxide concentration within the industry at which nitrogen oxides can be discharged directly into the atmosphere;

[0092] Step S202: If only ammonia exists in the initially treated exhaust gas and no nitrogen oxides exist, the ammonia concentration is detected;

[0093] When the ammonia concentration is greater than or equal to the maximum ammonia concentration, the second valve is opened to input the primary treated tail gas into the first zeolite adsorption device, and the process proceeds to step S400;

[0094] When the ammonia concentration is less than the maximum ammonia concentration, it is determined that the primary treated tail gas meets the emission standards, and the third valve is opened to discharge the primary treated tail gas;

[0095] Step S203: If both nitrogen oxides and ammonia exist in the initially treated exhaust gas, the concentrations of nitrogen oxides and ammonia are detected respectively;

[0096] When the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration and the ammonia concentration is less than the maximum ammonia concentration, it is determined that the primary treated exhaust meets the emission standards, and the third valve is opened to discharge the primary treated exhaust;

[0097] When the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, or the ammonia concentration is greater than or equal to the maximum ammonia concentration, the first valve is opened to input the primary treated exhaust gas into the second SCR denitrification device, and step S300 is entered.

[0098] Step S300, obtaining device data of a second SCR denitrification device, passing the primary treated exhaust gas through the second SCR denitrification device for secondary denitrification treatment to obtain secondary treated exhaust gas, and performing detection and analysis on the secondary treated exhaust gas;

[0099] The device data specifically includes the minimum valve opening and maximum valve opening of the ammonia input into the second SCR denitrification device;

[0100] In specific implementation, the minimum valve opening is 10%, specifically 36°; the maximum valve opening is 90%, specifically 324°;

[0101] It should be specifically noted that the valve opening is used to control the flow rate of ammonia in the second SCR denitrification device;

[0102] In this embodiment, step S300 includes the following sub-steps:

[0103] Step S301, obtaining the minimum valve opening XMK and the maximum valve opening DMK of the second SCR denitration device;

[0104] Step S302: Set the minimum nitrogen oxide boundary concentration XBN and the maximum nitrogen oxide boundary concentration DBN, and obtain the nitrogen oxide concentration DYN in the primary treated exhaust gas; calculate the valve opening FMK of the second SCR denitration device by the formula, which is as follows:

[0105] FMK=XMK, DYN≤XBN;

[0106] FMK=XMK+(DYN-XBN) / (DBN-XBN), XBN<DYN<DBN;

[0107] FMK=DMK, DYN≥DBN;

[0108] Step S303, recording the primary treated tail gas processed by the second SCR denitration device as secondary treated tail gas;

[0109] When the ammonia concentration in the secondary treated tail gas is less than the maximum ammonia concentration and the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, the secondary treated tail gas is discharged;

[0110] When the ammonia concentration in the secondary treated tail gas is less than the maximum ammonia concentration and the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the secondary treated tail gas is subjected to denitrification treatment again until the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, and then the secondary treated tail gas is discharged;

[0111] When the ammonia concentration in the secondary treated tail gas is greater than or equal to the maximum ammonia concentration and the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, the secondary treated tail gas is input into the first zeolite adsorption device;

[0112] When the ammonia concentration in the secondary treated exhaust gas is greater than or equal to the maximum ammonia concentration, and the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the secondary treated exhaust gas is denitrified again until the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, and the secondary treated exhaust gas is input into the first zeolite adsorption device.

[0113] Step S400: Inputting the tail gas to be treated into the first zeolite adsorption device for adsorption treatment, and determining whether to discharge the tail gas to be treated based on the adsorption treatment result;

[0114] Specifically, the primary treated tail gas and the secondary treated tail gas are combined and recorded as tail gas to be treated;

[0115] The first zeolite adsorption device is used to adsorb ammonia in the tail gas to be treated through zeolite, and when the zeolite is heated, the ammonia is desorbed from the zeolite;

[0116] In this embodiment, step S400 includes the following sub-steps:

[0117] Step S401: Testing the first zeolite adsorption device. If the ammonia concentration in the first zeolite adsorption device is greater than or equal to the zeolite ammonia concentration threshold, it is determined that the ammonia in the first zeolite adsorption device is not completely desorbed, and the first zeolite adsorption device is heated to a standard desorption temperature range. When the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, heating is stopped, and the adsorption temperature of the first zeolite adsorption device is set to the standard adsorption temperature range.

[0118] If the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, setting the adsorption temperature of the first zeolite adsorption device to the standard adsorption temperature range;

[0119] In a specific implementation, the minimum endpoint value of the standard desorption temperature range is 150°C and the maximum endpoint value is 250°C;

[0120] The minimum endpoint value of the standard adsorption temperature range is 30°C, and the maximum endpoint value is 100°C. When the adsorption temperature is less than 30°C or greater than 100°C, the efficiency of zeolite in capturing ammonia decreases and the capture cost increases;

[0121] Step S402, inputting the tail gas to be treated into a first zeolite adsorption device for adsorption;

[0122] Step S403, obtaining the final ammonia concentration of the tail gas to be treated after adsorption is completed, and if the final ammonia concentration is less than or equal to the maximum ammonia concentration, the tail gas to be treated is discharged;

[0123] If the final ammonia concentration is still greater than the maximum ammonia concentration, the tail gas to be treated is input into the second zeolite adsorption device. When the tail gas to be treated is completely input into the second zeolite adsorption device, the first zeolite adsorption device is closed, and the primary treated tail gas from the first SCR denitration device and the secondary treated tail gas from the second SCR denitration device are simultaneously input into the second zeolite adsorption device.

[0124] The final ammonia concentration is specifically the ammonia concentration of the tail gas to be treated after being adsorbed by the first zeolite adsorption device;

[0125] Step S404, heating the first zeolite adsorption device to a standard desorption temperature range, inputting the ammonia in the first zeolite adsorption device into the ammonia storage device, and closing the first zeolite adsorption device when the ammonia concentration in the first zeolite adsorption device is less than or equal to the minimum ammonia concentration;

[0126] Specifically, the ammonia storage device is connected to the first SCR denitrification device and the second SCR denitrification device for recovery and secondary utilization of ammonia;

[0127] Step S405, detecting the final ammonia concentration in the second zeolite adsorption device, and discharging the tail gas to be treated if the final ammonia concentration is less than or equal to the maximum ammonia concentration;

[0128] If the final ammonia concentration is greater than the maximum ammonia concentration, the above steps are repeated until the final ammonia concentration is less than or equal to the maximum ammonia concentration, and the tail gas to be treated is discharged;

[0129] It should be specifically explained that when the zeolite adsorption of ammonia in the first zeolite adsorption device reaches the maximum adsorption capacity, the first zeolite adsorption device cannot adsorb the ammonia in the exhaust gas to be treated. At this time, the remaining exhaust gas to be treated and the newly generated exhaust gas to be treated are input into the second zeolite adsorption device, and the ammonia in the first zeolite adsorption device is desorbed at the same time, and the ammonia generated by desorption is input into the ammonia storage device; when the ammonia concentration in the first zeolite adsorption device is less than or equal to the minimum ammonia concentration, the first zeolite adsorption device can adsorb the ammonia in the exhaust gas to be treated again. Similarly, the working process of the second zeolite adsorption device can be obtained. The first zeolite adsorption device and the second zeolite adsorption device alternately adsorb ammonia in the exhaust gas to be treated.

[0130] In this application, if a corresponding calculation formula appears, the above calculation formula is dimensionless and its numerical calculation is performed. The weight coefficient, proportional coefficient and other coefficients in the formula are set to a result value obtained by quantifying each parameter. Regarding the size of the weight coefficient and the proportional coefficient, as long as it does not affect the proportional relationship between the parameter and the result value, it is acceptable.

[0131] Example 2: This embodiment of the present invention further provides a computer device for running the above-mentioned method for treating exhaust gas from a two-stroke marine diesel engine; Figure 5 The structure diagram of a computer device provided by an embodiment of the present invention is shown, wherein the computer device includes a memory and a processor, wherein the memory is used to store one or more computer instructions, and the one or more computer instructions are executed by the processor to implement the above-mentioned method for treating exhaust gas from a two-stroke marine diesel engine;

[0132] Further, Figure 5 The computer device shown further includes a communication bus and a communication interface, and the processor, the communication interface and the memory are connected via the communication bus;

[0133] The memory may include high-speed random access memory (RAM) and may also include non-volatile memory, such as at least one disk storage. The communication connection between the system network element and at least one other network element is achieved through at least one communication interface (which can be wired or wireless), and the Internet, wide area network, local area network, metropolitan area network, etc. can be used. The communication bus can be an ISA bus, PCI bus or EISA bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5 Only one bidirectional arrow is used, but it does not mean that there is only one communication bus or one type of communication bus;

[0134] The processor may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method may be completed by hardware integrated logic circuits in the processor or by software instructions. The above processor may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. The methods, steps, and logic block diagrams disclosed in the embodiments of the present invention may be implemented or executed. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the method disclosed in conjunction with the embodiments of the present invention may be directly implemented and executed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module may be located in a storage medium well-known in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or the like. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the method of the above embodiment in combination with its hardware.

[0135] In a third embodiment, the present invention further provides a computer storage medium storing computer-executable instructions. When the computer-executable instructions are called and executed by a processor, the computer-executable instructions prompt the processor to implement the above-mentioned method for treating exhaust gas from a two-stroke marine diesel engine. For specific implementation, please refer to the method embodiment and will not be described in detail here.

[0136] A computer program product for a two-stroke marine diesel engine exhaust treatment method provided in an embodiment of the present invention includes a computer storage medium storing program code. The instructions included in the program code can be used to execute the method in the previous method embodiment. The specific implementation can be found in the method embodiment and will not be repeated here.

[0137] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working process of the system and / or device described above can refer to the corresponding process in the aforementioned method embodiment and will not be repeated here.

[0138] In addition, in the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0139] If the functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include various media capable of storing program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating exhaust gas from a two-stroke marine diesel engine, characterized in that: Here’s how: Step S100, obtaining historical exhaust data of the diesel engine, performing digestion, purification and denitrification treatment on the diesel engine exhaust through a first SCR denitrification device to obtain primary treated exhaust gas; Wherein, the step S100 includes the following sub-steps: Step S101: Obtain the historical diesel engine exhaust temperature CYW, the historical diesel engine exhaust output rate SCS, and the historical nitrogen oxide concentration DYN in the diesel engine exhaust. Convert the historical nitrogen oxide concentration to the nitrogen oxide molar flow rate MRL using the ideal gas formula. The specific formula is as follows: MRL=(SCS×DYN×10-6×P) / (R×CYW), where the unit of nitrogen oxide molar flow rate is moles per second; P is the atmospheric pressure, and R is the gas constant; In step S102, the molar flow rate of the urea aqueous solution NRS is calculated based on the molar flow rate of nitrogen oxides using the formula, which is as follows: NRS=MRL / 2; Step S103: Obtain the solution concentration RND, solution density RMD, and solution molar mass RMZ of the urea aqueous solution, and calculate the standard spraying rate PSS of the urea aqueous solution using the formula. The specific formula is as follows: PSS=(NRS×RMZ) / (RND×RMD); Step S104, setting the spraying rate of the urea aqueous solution in the first SCR denitrification device to a standard spraying rate, and inputting the diesel engine exhaust gas into the first SCR denitrification device for denitrification treatment to obtain the primary treated exhaust gas of the diesel engine; Step S200, detecting the gas type and gas concentration in the primary treated exhaust gas of the diesel engine, and analyzing the detection results; Wherein, the step S200 includes the following sub-steps: Step S201: If only nitrogen oxides exist in the initially treated exhaust gas and no ammonia exists, the concentration of nitrogen oxides is detected; When the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the first SCR denitrification device opens the first valve to input the primary treated exhaust gas into the second SCR denitrification device, and enters step S300; When the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, it is determined that the primary treated exhaust gas meets the emission standard, and the third valve is opened to discharge the primary treated exhaust gas; Step S202: If only ammonia exists in the initially treated exhaust gas and no nitrogen oxides exist, the ammonia concentration is detected; When the ammonia concentration is greater than or equal to the maximum ammonia concentration, the second valve is opened to input the primary treated tail gas into the first zeolite adsorption device, and the process proceeds to step S400; When the ammonia concentration is less than the maximum ammonia concentration, it is determined that the primary treated tail gas meets the emission standards, and the third valve is opened to discharge the primary treated tail gas; Step S203: If both nitrogen oxides and ammonia exist in the initially treated exhaust gas, the concentrations of nitrogen oxides and ammonia are detected respectively; When the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration and the ammonia concentration is less than the maximum ammonia concentration, it is determined that the primary treated exhaust meets the emission standards, and the third valve is opened to discharge the primary treated exhaust; When the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, or the ammonia concentration is greater than or equal to the maximum ammonia concentration, the first valve is opened to input the primary treated exhaust gas into the second SCR denitration device, and the process proceeds to step S300; Step S300, obtaining device data of a second SCR denitrification device, passing the primary treated exhaust gas through the second SCR denitrification device for secondary denitrification treatment to obtain secondary treated exhaust gas, and performing detection and analysis on the secondary treated exhaust gas; Wherein, the step S300 includes the following sub-steps: Step S301, obtaining the minimum valve opening XMK and the maximum valve opening DMK of the second SCR denitration device; Step S302: Set the minimum nitrogen oxide boundary concentration XBN and the maximum nitrogen oxide boundary concentration DBN, and simultaneously obtain the nitrogen oxide concentration DYN in the primary treated exhaust gas; and calculate the valve opening FMK of the second SCR denitration device through a formula; Step S303, recording the primary treated tail gas processed by the second SCR denitration device as secondary treated tail gas; When the ammonia concentration in the secondary treated tail gas is less than the maximum ammonia concentration and the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, the secondary treated tail gas is discharged; When the ammonia concentration in the secondary treated tail gas is less than the maximum ammonia concentration and the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the secondary treated tail gas is subjected to denitrification treatment again until the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, and then the secondary treated tail gas is discharged; When the ammonia concentration in the secondary treated tail gas is greater than or equal to the maximum ammonia concentration and the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, the secondary treated tail gas is input into the first zeolite adsorption device; When the ammonia concentration in the secondary treated tail gas is greater than or equal to the maximum ammonia concentration and the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the secondary treated tail gas is subjected to denitration treatment again until the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, and the secondary treated tail gas is input into the first zeolite adsorption device; Step S400: Inputting the tail gas to be treated into the first zeolite adsorption device for adsorption treatment, and determining whether to discharge the tail gas to be treated based on the adsorption treatment result; Wherein, the step S400 includes the following sub-steps: Step S401: Testing the first zeolite adsorption device. If the ammonia concentration in the first zeolite adsorption device is greater than or equal to the zeolite ammonia concentration threshold, it is determined that the ammonia in the first zeolite adsorption device is not completely desorbed, and the first zeolite adsorption device is heated to a standard desorption temperature range. When the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, heating is stopped, and the adsorption temperature of the first zeolite adsorption device is set to the standard adsorption temperature range. If the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, setting the adsorption temperature of the first zeolite adsorption device to the standard adsorption temperature range; Step S402, inputting the tail gas to be treated into a first zeolite adsorption device for adsorption; Step S403, obtaining the final ammonia concentration of the tail gas to be treated after adsorption is completed, and if the final ammonia concentration is less than or equal to the maximum ammonia concentration, the tail gas to be treated is discharged; If the final ammonia concentration is still greater than the maximum ammonia concentration, the exhaust gas to be treated is input into the second zeolite adsorption device. When the exhaust gas to be treated is completely input into the second zeolite adsorption device, the first zeolite adsorption device is closed, and the primary treated exhaust gas from the first SCR denitration device and the secondary treated exhaust gas from the second SCR denitration device are simultaneously input into the second zeolite adsorption device; wherein the final ammonia concentration is the ammonia concentration of the exhaust gas to be treated after the adsorption treatment by the first zeolite adsorption device; Step S404, heating the first zeolite adsorption device to a standard desorption temperature range, inputting the ammonia in the first zeolite adsorption device into the ammonia storage device, and closing the first zeolite adsorption device when the ammonia concentration in the first zeolite adsorption device is less than or equal to the minimum ammonia concentration; Step S405, detecting the final ammonia concentration in the second zeolite adsorption device, and discharging the tail gas to be treated if the final ammonia concentration is less than or equal to the maximum ammonia concentration; If the final ammonia concentration is greater than the maximum ammonia concentration, the above steps are repeated until the final ammonia concentration is less than or equal to the maximum ammonia concentration, and the tail gas to be treated is discharged.

2. A two-stroke marine diesel engine exhaust treatment method according to claim 1, characterized in that: The historical exhaust gas data includes the historical exhaust gas temperature of the diesel engine, the historical exhaust gas output rate of the diesel engine, and the historical concentration of nitrogen oxides in the diesel engine exhaust.

3. The method for treating exhaust gas from a two-stroke marine diesel engine according to claim 1, wherein: The device data specifically includes the minimum valve opening and the maximum valve opening for inputting ammonia into the second SCR denitrification device.

4. The method for treating exhaust gas from a two-stroke marine diesel engine according to claim 1, wherein: The formula of the valve opening FMK in step S300 is specifically: FMK=XMK, DYN≤XBN; FMK=XMK+(DYN-XBN) / (DBN-XBN), XBN<DYN<DBN; FMK=DMK, DYN≥DBN.

5. A two-stroke marine diesel engine exhaust treatment method according to claim 4, characterized in that: The primary treated tail gas and the secondary treated tail gas are combined and recorded as the tail gas to be treated.

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