Calculation method and system for minimum urea injection amount of SCR system of low-speed diesel engine

Abstract

The present invention provides a method and system for calculating the minimum urea injection amount of a low-speed diesel engine SCR system, wherein the diesel engine bench test parameters are obtained, and the current NO corresponding to each load under emission level 2 and emission level 3 is calculated respectively. x Measured emissions; Calculate NO for each current load x Conversion rate; Under the worst conditions, calculate the worst NOx corresponding to each load under emission level 2 and emission level 3 respectively. x Emissions; calculate the minimum NO emissions under the worst conditions for each load x conversion rate; obtain the actual urea injection amount under emission level 3; according to the actual urea injection amount, the NO x Conversion rate and minimum NO x The conversion rate is calculated to obtain the minimum urea injection amount corresponding to each load. The present invention can verify whether the urea injection system is normal and whether the ship meets the Tier 3 emission requirements during operation through the minimum urea injection amount.

Description

Technical Field

[0001] The present invention relates to the technical field of diesel engines, and in particular to a method and system for calculating a minimum urea injection amount of an SCR system of a low-speed diesel engine, and also provides a corresponding terminal and a computer-readable storage medium. Background Art

[0002] In order to reduce the pollution of exhaust gas emitted by ships during navigation, the SCR system is designed to meet the revised MARPOL Annex VI NO. x The International Maritime Organization (IMO) Technical Code 2008 (NTC2008) stipulates that the emission level of nitrogen oxides (NO x ) standard. For low-speed diesel engines with a speed of 130 rpm, when sailing in the ECA area, IMO NO x The cycle value must meet the requirement of not exceeding the limit of 3.4g / kwh (Tier 3); when sailing in non-ECA areas, IMO NO x The cycle value must meet the requirement of not exceeding the limit of 14.4g / kwh (Tier 2).

[0003] The SCR system is a system that injects a reducing agent (urea in this case) and removes NO in the exhaust gas. x Chemical reaction technology to reduce NO in exhaust gas x concentration, thereby reducing NO x Emissions and reduce pollution to the environment.

[0004] Therefore, determining the minimum injection amount of urea in the diesel engine SCR system during ship operation is very important for controlling emissions and meeting IMOTier3 NO x Standardization is essential.

[0005] At present, no description or report of similar technology to the present invention has been found, and similar information at home and abroad has not been collected yet. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method and system for calculating the minimum urea injection amount of a low-speed diesel engine SCR system, and also provides a corresponding terminal and a computer-readable storage medium.

[0007] The present invention is achieved through the following technical solutions.

[0008] According to one aspect of the present invention, a method for calculating the minimum urea injection amount of a low-speed diesel engine SCR system is provided, comprising:

[0009] Obtain the diesel engine bench test parameters, and calculate the current NO corresponding to each load under emission level 2 and emission level 3 based on the test parameters. x Measured emissions;

[0010] According to the current NO x Measure the emissions and calculate the NOx of each load x Conversion rate;

[0011] Based on the current NO x The measured emissions, under the worst conditions, calculate the worst NOx corresponding to each load under emission level 2 and emission level 3 respectively. x Emissions;

[0012] According to the worst NO x Emissions, calculate the minimum NOx under the worst conditions for each load x Conversion rate;

[0013] Obtaining the measured urea injection amount under emission level three;

[0014] According to the measured urea injection amount, the NO x Conversion rate and minimum NO x The conversion rate is calculated to obtain the minimum urea injection amount corresponding to each load.

[0015] Optionally, the test parameters include: diesel engine performance data and SCR system related data approved by the test classification society.

[0016] Optionally, each load under the emission level 2 and the emission level 3 includes: 25%, 50%, 75% and 100%.

[0017] Optionally, the current NO x The measured emissions are based on the IMO NO x Calculation method or NO established by the patentee of marine diesel engine and accepted by classification society x Calculation method:

[0018] Optionally, according to the current NO x Measure the emissions and calculate the NOx of each load x Conversion rate, including:

[0019] The current NO corresponding to each load under emission level 2 (Tier 2) and emission level 3 (Tier 3) x The measured emissions are A and B respectively, so the NO x The conversion rate N% is: N%=1-B / A.

[0020] Optionally, the worst condition refers to a situation where the maximum allowable emission amount that can be achieved by satisfying the emission limit value.

[0021] Optionally, the worst NO x The emission is based on the NOx set by the marine diesel engine patentee and accepted by the classification society. x Calculation method:

[0022] Optionally, according to the worst NO x Emissions, calculate the minimum NOx under the worst conditions for each load x Conversion rate, including:

[0023] Worst NOx corresponding to each load under the worst conditions for emission level 2 (Tier 2) and emission level 3 (Tier 3) x The emissions are A worse and B worse , then the minimum NO of each load under the worst conditions x Conversion rate N min %: N min % = 1-B worse / A worse .

[0024] Optionally, according to the measured urea injection amount, the NO x Conversion rate and minimum NO x Conversion rate, calculate the minimum urea injection amount corresponding to each load, including:

[0025] The measured urea injection amount under emission level 3 is D, and the minimum urea injection amount corresponding to each load is D min is: N / N min =D / D min ;D min =D×N min / N; where N is the NO of each load at present x Conversion rate, N min The minimum NO x Conversion rate.

[0026] According to another aspect of the present invention, a calculation system for a minimum urea injection amount of a low-speed diesel engine SCR system is provided, comprising:

[0027] A data acquisition module, which is used to obtain the diesel engine bench test parameters and the actual urea injection amount under emission level three;

[0028] A data calculation module is used to calculate the current NO corresponding to each load under emission level 2 and emission level 3 based on the test parameters. x Measured emissions; according to the current NOx Measure the emissions and calculate the NOx of each load x Conversion rate; based on the current NO x The measured emissions, under the worst conditions, calculate the worst NOx corresponding to each load under emission level 2 and emission level 3 respectively. x Emissions; based on the worst NO x Emissions, calculate the minimum NOx under the worst conditions for each load x conversion rate; according to the measured urea injection amount, the current NO x Conversion rate and minimum NO x The conversion rate is calculated to obtain the minimum urea injection amount corresponding to each load.

[0029] According to a third aspect of the present invention, a terminal is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor can be used to execute any of the above-described methods when executing the program.

[0030] According to a fourth aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, can be used to execute any of the methods described above.

[0031] Due to the adoption of the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art:

[0032] The method and system for calculating the minimum urea injection amount of the SCR system of a low-speed diesel engine provided by the present invention can calculate the minimum NOx emission under the maximum allowable value during ship navigation. x The minimum urea injection amount of the conversion rate is used to determine whether the urea injection system is normal.

[0033] The method and system for calculating the minimum urea injection amount of the SCR system of a low-speed diesel engine provided by the present invention can determine whether the diesel engine meets the Tier 3 requirement by verifying whether the urea injection amount exceeds the minimum urea injection amount (i.e., the minimum urea injection amount) during ship navigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0035] Figure 1 The figure is a working flow chart of a method for calculating the minimum urea injection amount of a low-speed diesel engine SCR system in a preferred embodiment of the present invention.

[0036] Figure 2The figure is a schematic diagram of the components of a system for calculating the minimum urea injection amount of an SCR system of a low-speed diesel engine in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following is a detailed description of the embodiments of the present invention: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

[0038] An embodiment of the present invention provides a method for calculating the minimum urea injection amount of a low-speed diesel engine SCR system, which can obtain the minimum NOx emission under the maximum allowable value. x The minimum urea injection amount for the conversion rate can be used to verify whether the urea injection system is normal and whether the Tier 3 emission requirements are met during ship operation.

[0039] like Figure 1 As shown, the calculation method of the minimum urea injection amount of the SCR system of a low-speed diesel engine provided by this embodiment may include:

[0040] S1, obtain the diesel engine bench test parameters, and calculate the current NO corresponding to each load under emission level 2 and emission level 3 based on the test parameters. x Measured emissions;

[0041] S2, according to the current NO x Measure the emissions and calculate the NOx of each load x Conversion rate;

[0042] S3, based on the current NO x The measured emissions, under the worst conditions, calculate the worst NOx corresponding to each load under emission level 2 and emission level 3 respectively. x Emissions;

[0043] S4, based on the worst NO x Emissions, calculate the minimum NOx under the worst conditions for each load x Conversion rate;

[0044] S5, obtaining the actual measured injection amount of urea under emission level three;

[0045] S6, based on the measured urea injection amount, the current NO x Conversion rate and minimum NO x The conversion rate is calculated to obtain the minimum urea injection amount corresponding to each load.

[0046] In a preferred embodiment of S1, the test parameters may include: diesel engine performance data and SCR system related data approved by the test classification society.

[0047] In a preferred embodiment of S1, each load under emission level 2 and emission level 3 may include: 25%, 50%, 75% and 100%.

[0048] In a preferred embodiment of S1, the current NO x The measured emissions can be based on the IMO NO specified in NTC2008. x Calculation method or NO established by the patentee of marine diesel engine and accepted by classification society x Calculation method:

[0049] In a preferred embodiment of S2, according to the current NO x Measure the emissions and calculate the NOx of each load x Conversion rate, which can include:

[0050] The current NO corresponding to each load under emission level 2 (Tier 2) and emission level 3 (Tier 3) x The measured emissions are A and B respectively, so the NO x The conversion rate N% is: N%=1-B / A.

[0051] In a preferred embodiment of S3, the worst condition refers to: a situation where the maximum allowable emission amount that can be achieved by satisfying the emission limit value.

[0052] In a preferred embodiment of S3, the worst NO x The emission can be based on the NOx set by the marine diesel engine patentee and accepted by the classification society. x Calculation method:

[0053] Further, in S3, assuming that the measured emission at a certain load point is based on the explosion pressure measured by the bench test and corrected to 178.5 bara under ISO conditions, then assuming that the maximum allowable explosion pressure under ISO conditions defined by the diesel engine patent holder is (178.5+5) bara, where 5 bar is the pressure tolerance, and the emission generated by this 5 bar is additional and is obtained through theoretical calculation, then, the worst emission = bench measured emission + emission generated by each tolerance. Of course, the additional emission generated by the tolerance is not only the pressure tolerance, but also the temperature tolerance, etc. The calculation method of the worst emission is given by the diesel engine patent holder and approved by the classification society. Therefore, the minimum urea injection amount can be obtained by calculating the known worst emission.

[0054] In a preferred embodiment of S4, according to the worst NOx Emissions, calculate the minimum NOx under the worst conditions for each load x Conversion rate, which can include:

[0055] Worst NOx corresponding to each load under the worst conditions for emission level 2 (Tier 2) and emission level 3 (Tier 3) x The emissions are A worse and B worse , then the minimum NO of each load under the worst conditions x Conversion rate N min %: N min % = 1-B worse / A worse .

[0056] In a preferred embodiment of S6, the actual urea injection amount, the current NO x Conversion rate and minimum NO x Conversion rate, calculate the minimum urea injection amount corresponding to each load, which can include:

[0057] The measured urea injection amount under emission level 3 is D, so the minimum urea injection amount corresponding to each load is D min is: N / N min =D / D min ;D min =D×N min / N; where N is the NO of each load at present x Conversion rate, N min The minimum NO x Conversion rate.

[0058] The technical solution provided by the above embodiment of the present invention is further described below in conjunction with a preferred embodiment.

[0059] like Figure 1 As shown, the method for calculating the minimum urea injection amount of the SCR system of a low-speed diesel engine provided by the preferred embodiment includes the following steps:

[0060] Step 1: Submit the test data approved by the classification society based on the diesel engine test bench, including diesel engine performance data (power, speed, pressure, temperature, etc.), SCR system related data (urea injection amount, etc.), and obtain IMO NO specified in NTC2008. x Calculation method or marine diesel engine patent vendors and accepted by the classification society NO x Calculation method for obtaining the current NOx for each load (25%, 50%, 75%, 100%) of emission level 2 (T2) and emission level 3 (T3). xValues ​​A and B;

[0061] Step 2: Calculate the NO of each load x Conversion rate: N% = 1-B / A;

[0062] Step 3, get NO in step 1 x Based on the values, the worst NO values ​​of each load T2 and T3 under the worst conditions of this diesel engine are calculated. x Value A worse and B worse , where the worst condition specified is the maximum permissible emission value that can be achieved by meeting the emission limit value;

[0063] Step 4: Calculate the minimum NO under the worst load conditions. x Conversion rate: N min % = 1-B worse / A worse ;

[0064] Step 5, obtaining the urea injection amount D measured in the diesel engine bench test Tier 3;

[0065] Step 6, calculate the minimum urea injection amount for each load:

[0066] N / N min =D / D min

[0067] D min =D×N min / N

[0068] In the above steps:

[0069] The measured emission value of the diesel engine bench test Tier 2 is A, in g / kwh;

[0070] The measured emission value of Tier 3 diesel engine bench test is B, in g / kwh;

[0071] The worst emission value under the worst conditions defined by the diesel engine bench test Tier 2 is A worse , unit is g / kwh;

[0072] The worst emission value under the worst conditions defined by the diesel engine bench test Tier 3 is B worse , unit is g / kwh;

[0073] Diesel engine bench test Tier 2 to Tier 3NO x The actual conversion rate is N%;

[0074] Minimum NO under the worst conditions x The conversion rate is N min %;

[0075] The actual urea injection amount measured in the diesel engine bench test Tier 3 is D, in L / h;

[0076] Based on minimum NO x The minimum urea injection amount for conversion rate is D min , unit is L / h.

[0077] Table 1 shows the Tier 2 performance data of diesel engine bench test.

[0078] Table 2 shows the Tier 3 performance data of diesel engine bench test

[0079] Table 3 shows the emission values ​​of Tier 2 diesel engine bench test.

[0080] Table 4 shows the emission values ​​of Tier 3 diesel engine bench test.

[0081] Table 1

[0082]

[0083] Table 2

[0084]

[0085] Table 3

[0086]

[0087] *) Actual NOx emission values ​​of the prototype engine on the test bench, without ISO environmental correction

[0088] **) NOx emission values ​​of parent engine under reference conditions

[0089] ***) NOx emission value of the parent engine under the maximum allowable value (worst emission value under the worst conditions)

[0090] Table 4

[0091]

[0092] *) Actual NOx emission values ​​of the prototype engine on the test bench, without ISO environmental correction

[0093] **) NOx emission value of the parent engine under the maximum permissible value (worst emission value under the worst conditions)

[0094] The new method for calculating the minimum urea injection amount provided by the above embodiment of the present invention can obtain the minimum NOx emission under the maximum allowable value. xThe minimum urea injection amount of the conversion rate is used to determine whether the diesel engine meets the Tier 3 requirements and whether the urea injection system works normally when the ship is sailing by verifying whether the actual urea injection amount exceeds the minimum value of the urea injection amount (i.e. the minimum urea injection amount).

[0095] An embodiment of the present invention provides a system for calculating the minimum urea injection amount of an SCR system of a low-speed diesel engine.

[0096] like Figure 2 As shown, the calculation system of the minimum urea injection amount of the low-speed diesel engine SCR system provided by this embodiment may include:

[0097] A data acquisition module, which is used to obtain the diesel engine bench test parameters and the actual urea injection amount under emission level three;

[0098] Data calculation module, which calculates the current NO corresponding to each load under emission level 2 and emission level 3 based on the test parameters. x Measured emissions; based on current NO x Measure the emissions and calculate the NOx of each load x Conversion rate; based on current NO x The measured emissions, under the worst conditions, calculate the worst NOx corresponding to each load under emission level 2 and emission level 3 respectively. x Emissions; based on the worst NO x Emissions, calculate the minimum NOx under the worst conditions for each load x Conversion rate; based on the measured urea injection amount, NO x Conversion rate and minimum NO x The conversion rate is calculated to obtain the minimum urea injection amount corresponding to each load.

[0099] It should be noted that the steps in the method provided by the present invention can be implemented by using corresponding modules, devices, units, etc. in the system. Those skilled in the art can refer to the technical solution of the method to realize the composition of the system, that is, the embodiments in the method can be understood as preferred examples for constructing the system, which will not be elaborated here.

[0100] An embodiment of the present invention provides a terminal, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it can be used to execute any method in the above embodiments of the present invention.

[0101] Optionally, the memory is used to store programs; the memory may include volatile memory (English: volatile memory), such as random-access memory (English: random-access memory, abbreviated: RAM), such as static random-access memory (English: static random-access memory, abbreviated: SRAM), double data rate synchronous dynamic random access memory (English: Double Data Rate Synchronous Dynamic Random Access Memory, abbreviated: DDR SDRAM), etc.; the memory may also include non-volatile memory (English: non-volatile memory), such as flash memory (English: flash memory). The memory is used to store computer programs (such as applications, functional modules, etc. that implement the above method), computer instructions, etc., and the above computer programs, computer instructions, etc. can be partitioned and stored in one or more memories. And the above computer programs, computer instructions, data, etc. can be called by the processor.

[0102] The above-mentioned computer programs, computer instructions, etc. may be stored in one or more memories in partitions, and the above-mentioned computer programs, computer instructions, data, etc. may be called by a processor.

[0103] The processor is used to execute the computer program stored in the memory to implement the various steps of the method or various modules of the system involved in the above embodiments. For details, please refer to the relevant descriptions in the above method and system embodiments.

[0104] The processor and the memory may be independent structures or integrated structures. When the processor and the memory are independent structures, the memory and the processor may be coupled and connected via a bus.

[0105] An embodiment of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, it can be used to execute any method in the above embodiments of the present invention.

[0106] The above embodiment of the present invention provides a method and system for calculating the minimum urea injection amount of a low-speed diesel engine SCR system, through nitrogen oxides (NO x) conversion rate, emission values ​​of emission level two (Tier 2) and emission level three (Tier 3), and the urea injection amount of emission level three (Tier 3) during the test, and the minimum urea injection amount required under the Tier 3 state is calculated. Then, the minimum urea injection amount is obtained through a new algorithm. The minimum urea injection amount can be used to verify whether the urea injection system is normal and whether the ship can meet the Tier 3 emission requirements during operation.

[0107] Those skilled in the art know that, in addition to implementing the system and its various devices provided by the present invention in a purely computer-readable program code, the system and its various devices provided by the present invention can be made to implement the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices provided by the present invention can be considered as a hardware component, and the devices for implementing various functions included therein can also be considered as structures within the hardware component; the devices for implementing various functions can also be considered as both software modules for implementing the method and structures within the hardware component.

[0108] All matters not covered in the above embodiments of the present invention are well known in the art.

[0109] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for calculating the minimum urea injection amount of a low-speed diesel engine SCR system, characterized in that: include: Obtain the diesel engine bench test parameters, and calculate the current NO corresponding to each load under emission level 2 and emission level 3 based on the test parameters. x Measured emissions; According to the current NO x Measure the emissions and calculate the NOx of each load x Conversion rate; Based on the current NO x The measured emissions, under the worst conditions, calculate the worst NOx corresponding to each load under emission level 2 and emission level 3 respectively. x Emissions; According to the worst NO x Emissions, calculate the minimum NOx under the worst conditions for each load x Conversion rate; Obtaining the measured urea injection amount under emission level three; According to the measured urea injection amount, the NO x Conversion rate and minimum NO x Conversion rate, calculate the minimum urea injection amount corresponding to each load; According to the current NO x Measure the emissions and calculate the NOx of each load x Conversion rate, including: Current NOx for each load under Tier 2 and Tier 3 x The measured emissions are A and B respectively, so the NO x The conversion rate N% is: N% = 1-B / A; According to the worst NO x Emissions, calculate the minimum NOx under the worst conditions for each load x Conversion rate, including: Worst NOx corresponding to each load under the worst conditions for emission level 2 (Tier 2) and emission level 3 (Tier 3) x The emissions are A worse and B worse , then the minimum NO of each load under the worst conditions x Conversion rate N min %: N min % = 1-B worse / A worse ; According to the measured urea injection amount, the NO x Conversion rate and minimum NO x Conversion rate, calculate the minimum urea injection amount corresponding to each load, including: The measured urea injection amount under emission level 3 is D, and the minimum urea injection amount corresponding to each load is D min is: N / N min =D / D min ;D min =D×N min / N; where N is the NO of each load at present x Conversion rate, N min The minimum NO x Conversion rate.

2. The method for calculating the minimum urea injection amount of the SCR system of a low-speed diesel engine according to claim 1, characterized in that: Also includes any one or more of the following: - The test parameters include: diesel engine performance data and SCR system related data approved by the test classification society; - Each load under the emission level 2 and the emission level 3 includes: 25%, 50%, 75% and 100%; -The current NO x The measured emissions are based on the IMO NO x Calculation method or NO established by the patentee of marine diesel engine and accepted by classification society x Calculation method:

3. The method for calculating the minimum urea injection amount of the SCR system of a low-speed diesel engine according to claim 1, characterized in that: The worst condition refers to the situation where the maximum allowable emissions can be achieved while meeting the emission limit values.

4. The method for calculating the minimum urea injection amount of the SCR system of a low-speed diesel engine according to claim 1, characterized in that: The worst NO x The emission is based on the NOx set by the marine diesel engine patentee and accepted by the classification society. x Calculation method:

5. A calculation system for the minimum urea injection amount of a low-speed diesel engine SCR system, characterized in that: include: A data acquisition module, which is used to obtain the diesel engine bench test parameters and the actual urea injection amount under emission level three; A data calculation module is used to calculate the current NO corresponding to each load under emission level 2 and emission level 3 based on the test parameters. x Measured emissions; according to the current NO x Measure the emissions and calculate the NOx of each load x Conversion rate; based on the current NO x The measured emissions, under the worst conditions, calculate the worst NOx corresponding to each load under emission level 2 and emission level 3 respectively. x Emissions; based on the worst NO x Emissions, calculate the minimum NOx under the worst conditions for each load x conversion rate; according to the measured urea injection amount, the current NO x Conversion rate and minimum NO x The conversion rate is calculated to obtain the minimum urea injection amount corresponding to each load.

6. A terminal comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, it can be used to perform the method according to any one of claims 1 to 4.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, it can be used to execute the method according to any one of claims 1 to 4.

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