Tail gas treatment method for two-stroke marine diesel engine

Abstract

The invention discloses a tail gas treatment method for a two-stroke marine diesel engine, relates to the technical field of tail gas digestion and purification, and solves the problem that a contradictory relationship exists between ammonia gas escape and nitrogen oxide conversion rate in a current marine diesel engine tail gas treatment technology. The method comprises the following steps: carrying out digestion purification and denitration treatment on the diesel engine tail gas through the first SCR denitration device to obtain primarily treated tail gas; detecting the gas type and the gas concentration in the primarily treated tail gas of the diesel engine, and analyzing the detection result; performing secondary denitration treatment on the primarily treated tail gas through a second SCR denitration device to obtain secondarily treated tail gas, and detecting and analyzing the secondarily treated tail gas; the to-be-treated tail gas is input into the first zeolite adsorption device for adsorption treatment, whether the to-be-treated tail gas is discharged or not is judged according to the adsorption treatment result, and the nitrogen oxide emission requirement is met under the condition that ammonia gas escape is reduced.

Description

Technical Field

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

[0002] A two-stroke marine diesel engine is a low-speed, heavy-duty diesel engine designed specifically for large ocean-going ships. Its working principle is to complete a complete combustion cycle through one up-and-down movement of the piston (i.e., two strokes), including intake, compression, combustion, and exhaust. It has the characteristics of simple structure, large torque, and high fuel efficiency, and is usually widely used as the main propulsion power in container ships, oil tankers, bulk carriers, etc. Since a large amount of nitrogen oxides (NOx) are emitted during its combustion process, a tail gas after-treatment system, such as a selective catalytic reduction (SCR) device, is usually installed to meet the ship emission regulations.

[0003] In the prior art, in order to prevent or reduce the ammonia slip phenomenon that occurs during the injection of urea aqueous solution in the SCR technology, the injection amount of urea aqueous solution is usually reduced accordingly. This method will lead to a decrease in the conversion efficiency of nitrogen oxides and cannot meet the emission requirements of nitrogen oxides. However, when the injection amount of urea aqueous solution increases, although the conversion rate of nitrogen oxides can be increased, the risk of ammonia slip also increases accordingly, resulting in secondary pollution, and the urea consumption is too much, increasing the use cost. There is a contradictory relationship in the existing SCR technology during actual operation; Therefore, the present invention proposes a method for treating the tail gas of a two-stroke marine diesel engine. Summary of the Invention

[0004] The purpose of the present invention is to propose a method for treating the tail gas of a two-stroke marine diesel engine to solve the problems raised in the above background technique.

[0005] The technical problem to be solved by the present invention is: How to meet the emission requirements of nitrogen oxides while reducing ammonia slip.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: A method for treating the tail gas of a two-stroke marine diesel engine, the method is as follows: Step S100, obtain the historical tail gas data of the diesel engine, and perform digestion, purification, and denitrification treatment on the tail gas of the diesel engine through the first SCR denitrification device to obtain the initially treated tail gas; Step S200, detect the gas type and gas concentration in the initially treated tail gas of the diesel engine, and analyze the detection results; Step S300: Obtain the device data of the second SCR denitration device, subject the initially treated tail gas to secondary denitration treatment through the second SCR denitration device to obtain the secondary treated tail gas, and perform detection and analysis on the secondary treated tail gas. Step S400: Input the tail gas to be treated into the first zeolite adsorption device for adsorption treatment, and determine whether the tail gas to be treated is discharged according to the adsorption treatment result.

[0007] Furthermore, the historical tail gas data includes the historical tail gas temperature of the diesel engine, the historical tail gas output rate of the diesel engine, and the historical concentration of nitrogen oxides in the diesel engine tail gas.

[0008] Furthermore, the said step S100 includes the following sub-steps: Step S101: Obtain the historical tail gas temperature CYW of the diesel engine, the historical tail gas output rate SCS of the diesel engine, and the historical concentration DYN of nitrogen oxides in the diesel engine tail gas, and convert the historical concentration of nitrogen oxides into the molar flow rate MRL of nitrogen oxides through the ideal gas formula. The specific formula is as follows: MRL = (SCS × DYN × 10-6 × P) / (R × CYW), where the unit of the molar flow rate of nitrogen oxides is moles per second; where P is the atmospheric pressure and R is the gas constant; Step S102: Calculate the molar flow rate NRS of the urea aqueous solution through the formula according to the molar flow rate of nitrogen oxides. The specific formula is as follows: NRS = MRL / 2; Step S103: Obtain the solution concentration RND, the solution density RMD, and the solution molar mass RMZ of the urea aqueous solution, and calculate the standard spraying rate PSS of the urea aqueous solution through the formula. The specific formula is as follows: PSS = (NRS × RMZ) / (RND × RMD); Step S104: Set the spraying rate of the urea aqueous solution in the first SCR denitration device to the standard spraying rate, and input the diesel engine tail gas into the first SCR denitration device for denitration treatment to obtain the initially treated tail gas of the diesel engine.

[0009] Furthermore, the said step S200 includes the following sub-steps: Step S201: If there is only nitrogen oxide and no ammonia in the initially treated tail gas, detect the nitrogen oxide concentration. When the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the first SCR denitration device opens the first valve, inputs the initially treated tail gas into the second SCR denitration device, and enters step S300; When the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, it is determined that the initially treated tail gas meets the emission standard, the third valve is opened, and the initially treated tail gas is discharged; Step S202: If only ammonia exists in the initially treated tail gas and no nitrogen oxides exist, then detect the ammonia concentration. When the ammonia concentration is greater than or equal to the maximum ammonia concentration, open the second valve, input the initially treated tail gas into the first zeolite adsorption device, and proceed to step S400. When the ammonia concentration is less than the maximum ammonia concentration, determine that the initially treated tail gas meets the emission standard, open the third valve, and discharge the initially treated tail gas. Step S203: If both nitrogen oxides and ammonia exist in the initially treated tail gas, then detect the nitrogen oxide concentration and the ammonia concentration respectively. When the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration and at the same time the ammonia concentration is less than the maximum ammonia concentration, determine that the initially treated tail gas meets the emission standard, open the third valve, and discharge the initially treated tail gas. 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, open the first valve, input the initially treated tail gas into the second SCR denitration device, and proceed to step S300.

[0010] Further, the device data specifically refers to the minimum valve opening and the maximum valve opening for inputting ammonia in the second SCR denitration device.

[0011] Further, step S300 includes the following sub-steps: Step S301: Obtain 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 of nitrogen oxides, and at the same time obtain the nitrogen oxide concentration DYN in the initially treated tail gas; calculate the valve opening FMK of the second SCR denitration device through a formula. Step S303: Denote the initially treated tail gas that has been treated by the second SCR denitration device as the secondary treated tail gas. When the ammonia concentration in the secondary treated tail gas is less than the maximum ammonia concentration and at the same time the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, discharge the 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 greater than or equal to the maximum nitrogen oxide concentration, perform denitration treatment on the secondary treated tail gas again until the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, and then discharge the secondary treated tail gas. 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, input the secondary treated tail gas 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 denitrified 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.

[0012] Further, the formula for the valve opening FMK in the step S300 is specifically: FMK = XMK, DYN ≤ XBN; FMK = XMK + (DYN - XBN) / (DBN - XBN), XBN < DYN < DBN; FMK = DMK, DYN ≥ DBN.

[0013] Further, the primary-treated tail gas and the secondary-treated tail gas are combined and recorded as the tail gas to be treated.

[0014] Further, the step S400 includes the following sub-steps: Step S401, detect 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. Heat the first zeolite adsorption device to the standard desorption temperature range. When the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, stop heating and set the adsorption temperature of the first zeolite adsorption device to the standard adsorption temperature range; If the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, set the adsorption temperature of the first zeolite adsorption device to the standard adsorption temperature range; Step S402, input the tail gas to be treated into the first zeolite adsorption device for adsorption.

[0015] Further, the step S400 also includes the following sub-steps: Step S403, obtain the final ammonia concentration of the tail gas to be treated after adsorption. If the final ammonia concentration is less than or equal to the maximum ammonia concentration, discharge the tail gas to be treated; If the final ammonia concentration is still greater than the maximum ammonia concentration, input the tail gas to be treated into the second zeolite adsorption device. After the tail gas to be treated is completely input into the second zeolite adsorption device, close the first zeolite adsorption device, and at the same time input the primary-treated tail gas of the first SCR denitrification device and the secondary-treated tail gas of the second SCR denitrification device into the second zeolite adsorption device; wherein, the final ammonia concentration is the ammonia concentration of the tail gas to be treated after adsorption treatment by the first zeolite adsorption device; Step S404: Heat the first zeolite adsorption device to the standard desorption temperature range, and input the ammonia gas in the first zeolite adsorption device into the ammonia gas storage device. When the ammonia gas concentration in the first zeolite adsorption device is less than or equal to the minimum ammonia gas concentration, close the first zeolite adsorption device. Step S405: Detect the final ammonia gas concentration in the second zeolite adsorption device. If the final ammonia gas concentration is less than or equal to the maximum ammonia gas concentration, discharge the tail gas to be treated. If the final ammonia gas concentration is greater than the maximum ammonia gas concentration, repeat the above steps until the tail gas to be treated is discharged when the final ammonia gas concentration is less than or equal to the maximum ammonia gas concentration.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention first obtains the historical tail gas data of the diesel engine, and then uses the first SCR denitration device to decompose, purify and denitrate the diesel engine tail gas to obtain the initially treated tail gas. Detect the gas types and gas concentrations in the initially treated tail gas of the diesel engine, and analyze the detection results. 2. The present invention also obtains the device data of the second SCR denitration device, performs secondary denitration treatment on the initially treated tail gas through the second SCR denitration device to obtain the secondary treated tail gas, and detects and analyzes the secondary treated tail gas. Finally, input the tail gas to be treated into the first zeolite adsorption device for adsorption treatment, and determine whether the tail gas to be treated is discharged according to the adsorption treatment result. The present invention meets the emission requirements of nitrogen oxides while reducing ammonia escape. Description of the Drawings

[0017] For the convenience of those skilled in the art to understand, the present invention will be further described below with reference to the accompanying drawings.

[0018] Figure 1 It is the flowchart of the method of the present invention; Figure 2 It is the flowchart of treating the diesel engine tail gas in the present invention; Figure 3 It is the example diagram of the minimum valve opening in the present invention; Figure 4 It is the example diagram of the maximum valve opening in the present invention; Figure 5 It is the structural schematic diagram of the computer device in the present invention. Detailed Embodiments

[0019] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0020] Example 1. Please refer to Figures 1 - 4 As shown, the technical solution provided by the present invention is: a method for treating the exhaust gas of a two-stroke marine diesel engine, which is used for denitrifying nitrogen oxides in the diesel engine exhaust gas and adsorbing ammonia participating in the reaction to prevent ammonia escape. The method is as follows: Step S100: Obtain the historical exhaust gas data of the diesel engine, and perform digestion, purification and denitrification treatment on the diesel engine exhaust gas through the first SCR denitrification device to obtain the initially treated exhaust gas; Specifically, 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 gas; It should be specifically noted that the diesel engine exhaust gas includes polluting gases such as nitrogen oxides, carbon monoxide, hydrocarbons, and sulfur oxides. The first SCR denitrification device is used to perform pollution-free treatment on the nitrogen oxides in the diesel engine exhaust gas; the nitrogen oxides are specifically nitric oxide and nitrogen dioxide; Among them, the denitrification treatment is specifically to convert nitrogen oxides into nitrogen and water through ammonia, and at the same time reduce the concentration of nitrogen oxides; In this embodiment, the step S100 includes the following sub-steps: Step S101: Obtain the historical exhaust gas temperature CYW of the diesel engine, the historical exhaust gas output rate SCS of the diesel engine, and the historical concentration DYN of nitrogen oxides in the diesel engine exhaust gas, and convert the historical concentration of nitrogen oxides into the molar flow rate MRL of nitrogen oxides through the ideal gas formula. The formula is as follows: MRL = (SCS × DYN × 10-6 × P) / (R × CYW), where the unit of the molar flow rate of nitrogen oxides is moles per second; Among them, P is the atmospheric pressure. In specific implementation, P = 101 kPa; R is the gas constant, which represents the heat required for each mole of ideal gas to increase by one Kelvin temperature; the ideal gas specifically refers to the gas behavior when there is no intermolecular force and volume; Specifically, the conversion between the Kelvin temperature and the Celsius temperature is specifically: T(K) = t(°C) + 273.15, where T(K) is the Kelvin temperature and t(°C) is the Celsius temperature; Step S102: Calculate the molar flow rate NRS of the urea aqueous solution according to the molar flow rate of nitrogen oxides through the formula. The formula is as follows: NRS = MRL / 2; Among them, when the urea aqueous solution is heated, the urea aqueous solution generates ammonia and carbon dioxide through thermal decomposition reaction and hydrolysis reaction; Step S103, obtain the solution concentration RND, solution density RMD, and solution molar mass RMZ of the aqueous urea solution, and calculate the standard spraying rate PSS of the aqueous urea solution through the formula. The specific formula is as follows: PSS = (NRS × RMZ) / (RND × RMD), where the unit of the urea spraying rate is m³ / s; In specific implementation, the solution concentration of the aqueous urea solution is 32.5%, the solution density is 1090 kg / m³, and the solution molar mass is 0.06 kg / mol; Step S104, set the spraying rate of the aqueous urea solution in the first SCR denitration device to the standard spraying rate, and input the diesel engine exhaust gas into the first SCR denitration device for denitration treatment to obtain the primary treated exhaust gas of the diesel engine; It should be specifically noted that in this embodiment, only nitrogen, ammonia, and nitrogen oxides in the primary treated exhaust gas are analyzed; Step S200, detect the gas type and gas concentration in the primary treated exhaust gas of the diesel engine, and analyze the detection results; In this embodiment, the step S200 includes the following sub-steps: Step S201, if there is only nitrogen oxide in the primary treated exhaust gas and no ammonia, detect the nitrogen oxide concentration; since nitrogen usually exists in the primary treated exhaust gas after treatment, the nitrogen factor is not considered here; When the nitrogen oxide concentration is greater than or equal to the maximum nitrogen oxide concentration, the first SCR denitration device opens the first valve, inputs the primary treated exhaust gas into the second SCR denitration 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, the third valve is opened, and the primary treated exhaust gas is discharged; Among them, the nitrogen, ammonia, and nitrogen oxides in the primary treated exhaust 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; Specifically, the maximum nitrogen oxide concentration is specifically the nitrogen oxide concentration when nitrogen oxides in the industry can be directly discharged into the atmosphere; Step S202, if there is only ammonia in the primary treated exhaust gas and no nitrogen oxide, detect the ammonia concentration; When the ammonia concentration is greater than or equal to the maximum ammonia concentration, the second valve is opened, and the primary treated exhaust gas is input into the first zeolite adsorption device, and enters step S400; When the ammonia concentration is less than the maximum ammonia concentration, it is determined that the primary treated exhaust gas meets the emission standard, the third valve is opened, and the primary treated exhaust gas is discharged; Step S203: If nitrogen oxides and ammonia exist simultaneously in the initially treated tail gas, detect the concentrations of nitrogen oxides and ammonia respectively; When the concentration of nitrogen oxides is less than the maximum nitrogen oxide concentration and the concentration of ammonia is less than the maximum ammonia concentration at the same time, it is determined that the initially treated tail gas meets the emission standard, open the third valve, and discharge the initially treated tail gas; When the concentration of nitrogen oxides is greater than or equal to the maximum nitrogen oxide concentration, or the concentration of ammonia is greater than or equal to the maximum ammonia concentration, open the first valve, input the initially treated tail gas into the second SCR denitration device, and enter step S300.

[0021] Step S300: Obtain the device data of the second SCR denitration device, perform secondary denitration treatment on the initially treated tail gas through the second SCR denitration device to obtain the secondary treated tail gas, and detect and analyze the secondary treated tail gas; Among them, the device data is specifically the minimum valve opening and the maximum valve opening of the ammonia input into the second SCR denitration device; In specific implementation, the minimum valve opening is 10%, specifically 36°; the maximum valve opening is 90%, specifically 324°; It should be specifically noted that the valve opening is used to control the flow rate of ammonia in the second SCR denitration device; In this embodiment, step S300 includes the following sub-steps: Step S301: Obtain 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 of nitrogen oxides, and at the same time obtain the nitrogen oxide concentration DYN in the initially treated tail gas; calculate the valve opening FMK of the second SCR denitration device through the formula. The specific formula is as follows: FMK = XMK, DYN ≤ XBN; FMK = XMK + (DYN - XBN) / (DBN - XBN), XBN < DYN < DBN; FMK = DMK, DYN ≥ DBN; Step S303: Record the initially treated tail gas processed by the second SCR denitration device as the 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 at the same time, discharge the 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 greater than or equal to the maximum nitrogen oxide concentration, perform denitration treatment on the secondary treated tail gas again until the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, and then discharge the secondary treated tail gas; 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 denitrified again until the nitrogen oxide concentration is less than the maximum nitrogen oxide concentration, and then the secondary treated tail gas is input into the first zeolite adsorption device.

[0022] Step S400: Input the tail gas to be treated into the first zeolite adsorption device for adsorption treatment, and determine whether the tail gas to be treated is discharged according to the adsorption treatment result; Specifically, the primary treated tail gas and the secondary treated tail gas are combined and recorded as the tail gas to be treated; Among them, the first zeolite adsorption device is used to adsorb ammonia in the tail gas to be treated through zeolite. When the zeolite is heated, ammonia is desorbed from the zeolite; In this embodiment, the step S400 includes the following sub-steps: Step S401: Detect 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. Heat the first zeolite adsorption device to the standard desorption temperature range. When the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, stop heating, and set the adsorption temperature of the first zeolite adsorption device to the standard adsorption temperature range; If the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, set the adsorption temperature of the first zeolite adsorption device to the standard adsorption temperature range; In specific implementation, the minimum end point value of the standard desorption temperature range is 150 °C, and the maximum end point value is 250 °C; The minimum end point value of the standard adsorption temperature range is 30 °C, and the maximum end point value is 100 °C. When the adsorption temperature is less than 30 °C or greater than 100 °C, the efficiency of the zeolite in capturing ammonia decreases, and the capture cost increases; Step S402: Input the tail gas to be treated into the first zeolite adsorption device for adsorption; Step S403: Obtain the final ammonia concentration of the tail gas to be treated after adsorption. If the final ammonia concentration is less than or equal to the maximum ammonia concentration, discharge the tail gas to be treated; 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. After the tail gas to be treated is completely input into the second zeolite adsorption device, the first zeolite adsorption device is closed. At the same time, the primary treated tail gas of the first SCR denitration device and the secondary treated tail gas of the second SCR denitration device are input into the second zeolite adsorption device; Among them, the final ammonia concentration is specifically the ammonia concentration after the tail gas to be treated is adsorbed by the first zeolite adsorption device; Step S404: Heat the first zeolite adsorption device to the standard desorption temperature range, and input the ammonia in the first zeolite adsorption device 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, close the first zeolite adsorption device; Specifically, the ammonia storage device is connected to the first SCR denitration device and the second SCR denitration device, and is used for the recovery and secondary utilization of ammonia; Step S405: Detect the final ammonia concentration in the second zeolite adsorption device. 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 greater than the maximum ammonia concentration, repeat the above steps until the tail gas to be treated is discharged when the final ammonia concentration is less than or equal to the maximum ammonia concentration; It should be specifically noted that when the zeolite in the first zeolite adsorption device adsorbs ammonia to the maximum adsorption capacity, the first zeolite adsorption device cannot adsorb the ammonia in the tail gas to be treated. At this time, the remaining tail gas to be treated and the newly generated tail gas to be treated are input into the second zeolite adsorption device. At the same time, the ammonia in the first zeolite adsorption device is desorbed, and the desorbed ammonia 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 tail 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 the ammonia in the tail gas to be treated.

[0023] In this application, if there are corresponding calculation formulas, the above calculation formulas are all calculated by taking the numerical values after removing the dimensions. The coefficients such as the weight coefficient and the proportionality coefficient in the formula are set to obtain a result value by quantifying each parameter. Regarding the magnitudes of the weight coefficient and the proportionality coefficient, as long as the proportional relationship between the parameters and the result value is not affected.

[0024] Embodiment 2. The embodiment of the present invention also provides a computer device for running the described two-stroke marine diesel engine tail gas treatment method; see Figure 5Schematic structural diagram of a computer device provided by an embodiment of the present invention. The computer device includes a memory and a processor. 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 two-stroke marine diesel engine exhaust gas treatment method; Further, Figure 5 The shown computer device further includes a communication bus and a communication interface. The processor, the communication interface, and the memory are connected through the communication bus; Among them, the memory may include high-speed random access memory (RAM, Random Access Memory), and may also include non-volatile memory, such as at least one disk memory. The communication connection between the system network element and at least one other network element is realized 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, a PCI bus, an EISA bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of convenience of representation, Figure 5 only a bidirectional arrow is used in the figure, but it does not mean that there is only one communication bus or one type of communication bus; A processor may be an integrated circuit chip with the ability to process signals. In the implementation process, each step of the above method can be completed by the integrated logic circuit of the hardware in the processor or the instructions in the form of software. The above-mentioned processor may be a general-purpose processor, including a central processing unit (CPU for short), a network processor (NP for short), etc.; it may also be a digital signal processor (DSP for short), an application specific integrated circuit (ASIC for short), a field-programmable gate array (FPGA for short), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present invention can be directly embodied as being executed and completed by a hardware decoding processor, or executed and completed by a combination of the hardware and software modules in the decoding processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the method in the foregoing embodiments.

[0025] Embodiment 3. The embodiments of the present invention further provide a computer storage medium. The computer storage medium stores computer-executable instructions. When the computer-executable instructions are called and executed by a processor, the computer-executable instructions cause the processor to implement the above-mentioned method for treating the exhaust gas of a two-stroke marine diesel engine. For the specific implementation, reference may be made to the method embodiment, and details are not described herein again. A computer program product of the method for treating the exhaust gas of a two-stroke marine diesel engine provided by the embodiments 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 foregoing method embodiments. For the specific implementation, reference may be made to the method embodiment, and details are not described herein again.

[0026] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described system and / or device can refer to the corresponding processes in the foregoing method embodiments, and details are not described herein again.

[0027] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] If the above-mentioned functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The foregoing storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. However, such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for treating the exhaust gas of a two-stroke marine diesel engine, characterized in that, The method is as follows: Step S100: Obtain the historical exhaust gas data of the diesel engine, and perform digestion, purification, and denitrification treatment on the diesel engine exhaust gas through the first SCR denitrification device to obtain the initially treated exhaust gas; Step S200: Detect the gas type and gas concentration in the initially treated exhaust gas of the diesel engine, and analyze the detection results; Step S300: Obtain the device data of the second SCR denitrification device, perform secondary denitrification treatment on the initially treated exhaust gas through the second SCR denitrification device to obtain the secondary treated exhaust gas, and detect and analyze the secondary treated exhaust gas; Step S400: Input the exhaust gas to be treated into the first zeolite adsorption device for adsorption treatment, and determine whether the exhaust gas to be treated is discharged according to the adsorption treatment result.

2. A two-stroke marine diesel engine exhaust gas 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 gas.

3. A method for treating exhaust gas of a two-stroke marine diesel engine according to claim 2, characterized in that, The said Step S100 includes the following sub-steps: Step S101: Obtain the historical exhaust gas temperature CYW of the diesel engine, the historical exhaust gas output rate SCS of the diesel engine, and the historical concentration DYN of nitrogen oxides in the diesel engine exhaust gas. Convert the historical concentration of nitrogen oxides into the molar flow rate MRL of nitrogen oxides through the ideal gas formula. The specific formula is as follows: MRL = (SCS × DYN × 10-6 × P) / (R × CYW), where the unit of the molar flow rate of nitrogen oxides is moles per second; where P is the atmospheric pressure and R is the gas constant; Step S102: Calculate the molar flow rate NRS of the urea aqueous solution through the formula according to the molar flow rate of nitrogen oxides. The specific formula 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 through the formula. The specific formula is as follows: PSS = (NRS × RMZ) / (RND × RMD); Step S104: Set the spraying rate of the urea aqueous solution in the first SCR denitrification device to the standard spraying rate, and input the diesel engine exhaust gas into the first SCR denitrification device for denitrification treatment to obtain the initially treated exhaust gas of the diesel engine.

4. A method for treating exhaust gas of a two-stroke marine diesel engine according to claim 3, characterized in that, The said Step S200 includes the following sub-steps: Step S201: If there is only nitrogen oxide and no ammonia in the initially treated exhaust gas, detect the nitrogen oxide concentration; 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, inputs the initially 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 initially treated exhaust gas meets the emission standard, the third valve is opened, and the initially treated exhaust gas is discharged; Step S202: If there is only ammonia and no nitrogen oxide in the initially treated exhaust gas, detect the ammonia concentration; When the ammonia concentration is greater than or equal to the maximum ammonia concentration, the second valve is opened, and the initially treated exhaust gas is input into the first zeolite adsorption device, and enters Step S400; When the ammonia concentration is less than the maximum ammonia concentration, it is determined that the initially treated tail gas meets the emission standard, the third valve is opened, and the initially treated tail gas is discharged; Step S203: If both nitrogen oxides and ammonia exist in the initially treated tail 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 at the same time, it is determined that the initially treated tail gas meets the emission standard, the third valve is opened, and the initially treated tail gas is discharged; 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, and the initially treated tail gas is input into the second SCR denitration device, and step S300 is entered.

5. A method for treating exhaust gas of a two-stroke marine diesel engine according to claim 4, characterized in that, The device data is specifically the minimum valve opening and the maximum valve opening of the ammonia input into the second SCR denitration device.

6. A method for treating exhaust gas of a two-stroke marine diesel engine according to claim 5, characterized in that, The said step S300 includes the following sub-steps: Step S301: Obtain 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 of nitrogen oxides, and at the same time obtain the nitrogen oxide concentration DYN in the initially treated tail gas; calculate the valve opening FMK of the second SCR denitration device through the formula; Step S303: Record the initially treated tail gas treated by the second SCR denitration device as the 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 at the same time, 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 denitrified 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 denitrified 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.

7. A two-stroke marine diesel engine exhaust gas treatment method according to claim 6, characterized in that, The formula for the valve opening FMK in the said step S300 is specifically: FMK = XMK, DYN ≤ XBN; FMK = XMK + (DYN - XBN) / (DBN - XBN), XBN < DYN < DBN; FMK = DMK, DYN ≥ DBN.

8. A two-stroke marine diesel engine exhaust gas treatment method according to claim 7, characterized in that, The initially treated tail gas and the secondary treated tail gas are combined and recorded as the tail gas to be treated.

9. A method for treating exhaust gas of a two-stroke marine diesel engine according to claim 8, characterized in that, The said step S400 includes the following sub-steps: Step S401: Detect 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. Heat the first zeolite adsorption device to the standard desorption temperature range. Stop heating when the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, and set the adsorption temperature of the first zeolite adsorption device to the standard adsorption temperature range; If the ammonia concentration in the first zeolite adsorption device is less than the zeolite ammonia concentration threshold, set the adsorption temperature of the first zeolite adsorption device to the standard adsorption temperature range; Step S402: Input the tail gas to be treated into the first zeolite adsorption device for adsorption.

10. A method for treating exhaust gas of a two-stroke marine diesel engine according to claim 9, characterized in that, The step S400 further includes the following sub-steps: Step S403: Obtain the final ammonia concentration of the tail gas to be treated after adsorption. If the final ammonia concentration is less than or equal to the maximum ammonia concentration, discharge the tail gas to be treated; If the final ammonia concentration is still greater than the maximum ammonia concentration, input the tail gas to be treated into the second zeolite adsorption device. After the tail gas to be treated is completely input into the second zeolite adsorption device, close the first zeolite adsorption device, and at the same time input the primary treated tail gas of the first SCR denitration device and the secondary treated tail gas of the second SCR denitration device into the second zeolite adsorption device; wherein, the final ammonia concentration is the ammonia concentration of the tail gas to be treated after being adsorbed by the first zeolite adsorption device; Step S404: Heat the first zeolite adsorption device to the standard desorption temperature range, and input the ammonia in the first zeolite adsorption device into the ammonia storage device. Close 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: Detect the final ammonia concentration in the second zeolite adsorption device. If the final ammonia concentration is less than or equal to the maximum ammonia concentration, discharge the tail gas to be treated; If the final ammonia concentration is greater than the maximum ammonia concentration, repeat the above steps until the final ammonia concentration is less than or equal to the maximum ammonia concentration and then discharge the tail gas to be treated.

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