A method for determining the threshold value of ship exhaust emissions exceeding the standard based on multiple scenarios

Abstract

The present invention discloses a method for determining the threshold value of ship exhaust emission exceeding the standard that is adaptable to multiple scenarios, including: real-time collection of AIS parameters and meteorological parameters of ships that can be monitored by monitoring points; analysis and processing of the AIS parameters and meteorological parameters of each ship, obtaining the real-time atmospheric stability level and selecting the corresponding diffusion parameters; obtaining ship item parameters and calculating the ship exhaust emission rate according to the AIS parameters of the ship; determining the positions of all ships that can be monitored by the monitoring point, establishing a coordinate system based on the position of the ship and performing coordinate conversion, calculating the concentration distribution of the chimney of each ship; calculating the concentration threshold of the monitoring height according to the concentration distribution of the chimney of each ship. The present invention comprehensively considers the driving characteristics of the ship and the meteorological environment factors, further corrects the factors affecting the diffusion of exhaust gas, ensures the real-time performance of the threshold value of exhaust emission exceeding the standard, and can dynamically adjust the threshold value exceeding the standard, thereby improving the accuracy and efficiency of exhaust emission supervision.

Description

Technical Field

[0001] The invention relates to a method for determining a threshold value of ship exhaust emissions exceeding a standard that is adaptable to multiple scenarios, and belongs to the technical field of ship exhaust emission supervision. Background Art

[0002] Pollutants released from ship exhaust, especially sulfur dioxide, is one of the main sources of air pollution. The "Implementation Plan for Ship Air Pollutant Emission Control Areas" issued by the Ministry of Transport in 2018 has made more stringent regulations on the sulfur content limit of fuel quality, etc. Therefore, the demand for remote telemetry and online enforcement of ship exhaust pollutant emissions is increasing.

[0003] Existing ship exhaust emission supervision is mainly based on manual means, generally by boarding the ship to detect whether the sulfur content of marine fuel meets the relevant standards, but this method has lag and low supervision efficiency. In order to effectively supervise ship exhaust emissions, it is particularly necessary to deploy detection equipment above the bridge, set the threshold value of exceeding the standard, and remotely monitor the exhaust concentration, but the setting of the threshold value of exceeding the standard for exhaust is a key issue. If the differences under different working conditions are ignored, a fixed threshold is set according to past experience, and the same value is used for exhaust monitoring in all environments, different effects will be produced: for example, even if the meteorological conditions are exactly the same, for the case of a low monitoring height, the exhaust detection value will generally be larger than the fixed threshold, resulting in frequent false alarms, affecting the efficiency and effectiveness of maritime law enforcement; for the case of a high monitoring height, the exhaust detection value will generally be smaller than the fixed threshold, resulting in missed reports, which cannot meet the needs of ship exhaust control. In summary, it is of great significance to dynamically adjust the threshold value of exceeding the standard according to the real-time situation. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for determining the threshold value of ship exhaust emissions exceeding the standard that is adaptable to multiple scenarios, ensure the real-time nature of the threshold value of exhaust emissions exceeding the standard, and dynamically adjust the threshold value, so that the diffusion model has better adaptability.

[0005] The present invention adopts the following technical solutions to solve the above technical problems:

[0006] A method for determining a threshold value of ship exhaust emissions exceeding the standard that is suitable for multiple scenarios comprises the following steps:

[0007] Step 1, setting a monitoring point on the bridge, and collecting AIS parameters and meteorological parameters of the ship that can be monitored by the monitoring point in real time;

[0008] Step 2: Analyze and process the AIS parameters and meteorological parameters of each ship through the atmospheric stability level calculation method, obtain the real-time atmospheric stability level and select the corresponding diffusion parameters;

[0009] Step 3, according to the AIS parameters of the ship, obtain the ship item parameters and calculate the ship exhaust emission rate;

[0010] Step 4, determining the positions of all ships that can be monitored by the monitoring point, establishing a coordinate system based on the positions of the ships and performing coordinate conversion, and calculating the concentration distribution of the chimneys of each ship;

[0011] Step 5: Obtain the monitoring height according to the location of the monitoring point, and calculate the concentration threshold of the monitoring height according to the concentration distribution of each ship chimney.

[0012] As a preferred solution of the present invention, the AIS parameters in step 1 are obtained through AIS base stations deployed at monitoring points, and the AIS parameters include ship static parameters and ship dynamic parameters, wherein the ship static parameters include ship name, ship number and ship engine power, and the ship dynamic parameters include ship longitude, ship latitude and ship speed.

[0013] As a preferred embodiment of the present invention, the meteorological parameters in step 1 are obtained by a meteorological analyzer deployed at a monitoring point, and the meteorological parameters include wind speed and cloud cover.

[0014] As a preferred solution of the present invention, the specific process of step 2 is as follows:

[0015] Step 2.1, calculate the solar hour angle and solar inclination angle according to the ship's longitude and monitoring time, specifically:

[0016] ω=15t+j-300

[0017] σ=(0.006918-0.399912cosθ+0.0702578sinθ-0.006758cos2θ+0.000907sin2θ-0.002697cos3θ+0.00148sin3θ)*180 / π

[0018] Where, ω represents the solar hour angle; t represents the hour part of the monitoring time; j represents the ship's longitude; σ represents the solar inclination angle; d represents the ordinal number of the monitoring date in the whole year;

[0019] Step 2.2, calculate the solar altitude angle, specifically:

[0020] h=arcsin(sinw*sinσ+cosw*cosσ*cosω)

[0021] Wherein, h represents the solar altitude angle; w represents the latitude of the ship;

[0022] Step 2.3, according to the solar altitude angle, query the solar incidence level table to determine the solar incidence level;

[0023] Step 2.4, according to the solar incidence level and wind speed, query the atmospheric stability level table to determine the atmospheric stability level;

[0024] Step 2.5, according to the atmospheric stability level, query the diffusion parameter table to determine the atmospheric diffusion parameters.

[0025] As a preferred solution of the present invention, in step 3, the ship parameters include the height from the ship chimney to the sea level and the ship engine power, and the specific calculation formula for the ship exhaust emission rate is:

[0026] Q i =P i ×EF / 3600

[0027] Among them, Q i represents the exhaust emission rate of ship i; P i represents the engine power of ship i, kW; EF represents the emission factor of sulfur dioxide, g / (kW·h).

[0028] As a preferred solution of the present invention, the specific process of step 4 is as follows:

[0029] Step 4.1, take the projection of the exhaust gas monitoring point set on the bridge on the horizontal plane as the origin, the positive direction of the X-axis is the wind direction, the Y-axis is perpendicular to the X-axis on the horizontal plane, the positive direction is on the left side of the X-axis, and the Z-axis is located on the horizontal plane, with the upward direction as the positive direction; let the coordinates of each ship chimney be (X i ,Y i ,H i ), i = 1, 2, ..., n, n is the number of all ships that can be monitored at the monitoring point, X i ,Y i Obtained through the ship, monitoring point latitude and longitude and wind direction, H i represents the height from the chimney of ship i to the sea level;

[0030] Step 4.2, using each ship as the origin, establish different coordinate systems. The coordinates of each ship's chimney in its own coordinate system are (0, 0, H i ), assuming that the coordinates of the monitoring point P are (x, y, z), the exhaust concentration contribution of ship i to point P is C(x, y, z, H i ) is calculated as:

[0031]

[0032] Among them, Q i represents the exhaust emission rate of ship i, in kg / s; μ is the average wind speed, in m / s; σ y is the atmospheric diffusion coefficient on the Y axis, σz is the atmospheric diffusion coefficient on the Z axis, x is the downwind distance in meters, y is the crosswind distance in meters;

[0033] Step 4.3, set the total coordinate system, select the ship farthest from the monitoring point as the origin of the total coordinate system, and its coordinates are (X s ,Y s ,H s );

[0034] Step 4.4, coordinate transformation is performed on the remaining ships, and the coordinates of the remaining ships in the total coordinate system are (X i -X s ,Y i -Y s ,H i );

[0035] Step 4.5: Calculate the concentration distribution C of each ship at height z in the global coordinate system. i (X i -X s ,Y i -Y s ,z,H i ), the calculation formula is:

[0036]

[0037] in, represents the diffusion coefficient in the Y-axis direction.

[0038] As a preferred solution of the present invention, the concentration threshold of the monitoring height in step 5 is specifically:

[0039]

[0040] Where C represents the concentration threshold at the monitoring height, C i (X i -X s ,Y i -Y s ,z,H i ) represents the concentration distribution of ship i at height z, and n is the number of all ships that can be monitored at the monitoring point.

[0041] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0042] 1. The threshold setting method of the present invention comprehensively considers factors such as ship driving characteristics and meteorological environment, and further corrects the factors affecting exhaust gas diffusion, so that the real-time nature of the exhaust emission exceeding threshold is guaranteed, and the exceeding threshold can be dynamically adjusted, so that the diffusion model has better adaptability, thereby improving the accuracy and efficiency of exhaust emission supervision.

[0043] 2. The threshold setting method of the present invention can adjust the threshold value of ship exhaust emissions exceeding the standard according to different working conditions, thereby better improving the adaptability of the threshold value in different scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flow chart of a method for determining a threshold value of ship exhaust emissions exceeding the standard that is suitable for multiple scenarios of the present invention;

[0045] Figure 2 This is a suggested diagram of ship threshold values ​​obtained by using the method of the present invention. DETAILED DESCRIPTION

[0046] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention.

[0047] like Figure 1 As shown, it is a flow chart of a method for determining a threshold value of ship exhaust emissions exceeding the standard that is suitable for multiple scenarios of the present invention, and the specific steps are as follows:

[0048] S1: A monitoring point is set on the bridge to collect AIS parameters and meteorological parameters of the ship that can be monitored by the monitoring point in real time.

[0049] AIS parameters include static ship parameters and dynamic ship parameters. The static ship parameters include ship name, ship number and ship engine power, and the dynamic ship parameters include ship longitude and latitude and ship speed. Meteorological parameters include wind speed and cloud cover.

[0050] By deploying AIS base stations at monitoring points, the AIS parameters of ships can be obtained; by deploying meteorological analyzers at monitoring points, the meteorological parameters of monitoring points can be obtained.

[0051] S2: Through the atmospheric stability level calculation method, the AIS parameters and meteorological parameters of each ship are analyzed and processed to obtain the local real-time atmospheric stability level and select the corresponding diffusion parameters. The details are as follows:

[0052] S2.1: Calculate the solar hour angle and solar inclination angle based on the ship's longitude and local time, specifically:

[0053] ω=15t+j-300

[0054] σ=(0.006918-0.399912cosθ+0.0702578sinθ-0.006758cos2θ+0.000907sin2θ-0.002697cos3θ+0.00148sin3θ)*180 / π

[0055] Where ω represents the solar hour angle; t represents the hour part of the local time; j represents the ship's longitude; σ represents the solar inclination; and the calculation formula for θ is: d represents the ordinal number of the current date in the whole year.

[0056] S2.2: Get the solar altitude angle, specifically:

[0057] h=arcsin(sinw*sinσ+cosw*cosσ*cosω)

[0058] Wherein, h represents the solar altitude angle; w represents the latitude of the ship.

[0059] S2.3: Determine the solar incidence level, and obtain the specific value by referring to Table 1;

[0060] Table 1 Solar incidence level table

[0061]

[0062]

[0063] S2.4: Determine the atmospheric stability level based on the solar incidence level and wind speed. The specific value can be obtained from Table 2.

[0064] Table 2 Atmospheric stability level table

[0065]

[0066] S2.5: Determine the diffusion parameter σ based on the atmospheric stability level y and σ z , the specific value can be obtained by looking up Table 3.

[0067] Table 3 Diffusion parameters

[0068]

[0069]

[0070] Where x represents the downwind distance.

[0071] S3: According to the AIS parameters of the ship, obtain the ship item parameters and calculate the ship exhaust emission rate.

[0072] Ship parameters include ship chimney height, engine power, ship exhaust emission rate Q i The calculation is as follows:

[0073] Q i =P i ×EF / 3600

[0074] Among them, P i is the engine power of ship i, kW; EF is the emission factor of sulfur dioxide, g / (kW·h), and the emission factor is obtained from references.

[0075] S4: Determine the position of all ships that can be monitored by the monitoring point, and synchronously establish and convert the coordinate system based on the position of the ship. The details are as follows:

[0076] S4.1: The projection of the exhaust gas monitoring point set on the bridge on the horizontal plane is taken as the origin, the positive direction of the X-axis is the wind direction, the Y-axis is perpendicular to the X-axis on the horizontal plane, the positive direction is on the left side of the X-axis, and the Z-axis is located on the horizontal plane, with the upward direction as the positive direction. Assume that the coordinates of each ship chimney are (X i ,Y i ,H i ), i = 1, 2, ..., n, n is the number of all ships that can be monitored at the monitoring point, X i ,Y i Obtained through the ship, monitoring point latitude and longitude and wind direction, H i represents the height from the chimney of ship i to the sea level;

[0077] S4.2: Take each ship as the origin and establish different coordinate systems. The coordinates of each ship's chimney in each coordinate system are (0,0,H i ), assuming the coordinates of monitoring point P are (x, y, z), the exhaust concentration contribution of ship i to point P is C(x, y, z, H i ) is calculated as:

[0078]

[0079] Among them, Q is the exhaust emission rate (source strength), the unit is kg / s, μ is the average wind speed, the unit is m / s, σ y is the atmospheric diffusion coefficient on the Y axis, σ z is the atmospheric diffusion coefficient on the Z axis;

[0080] S4.3: Set up the overall coordinate system and select the ship farthest from the monitoring point as the overall coordinate origin. Its coordinates are (X s , Y s , H s );

[0081] S4.4: The other ships perform coordinate system conversion synchronously, and the relative coordinates in the same coordinate system are (X i -X s , Y i -Y s , H i );

[0082] S4.5: Under the new coordinate system, obtain the concentration distribution C of each ship emission source i (X i -X s ,Y i -Y s ,z,H i ), as follows:

[0083]

[0084] Where, z is the distance between the monitoring point P and the sea level, m; Q i is the exhaust emission rate, kg / s; H i is the distance between the emission source (chimney mouth) and the sea level, m; μ is the wind speed, m / s; σ y is the atmospheric diffusion coefficient on the Y axis, σ z is the atmospheric diffusion coefficient on the Z axis;

[0085] S5: Obtain the monitoring height according to the location of the monitoring equipment; calculate the concentration threshold of the monitoring height by calculating the concentration distribution of the ship emission source.

[0086] Monitoring height refers to the vertical distance between the location where the monitoring equipment is installed and the sea level, that is, z.

[0087] The concentration thresholds for monitoring heights are:

[0088]

[0089] Example

[0090] Taking the monitoring area - the downstream channel of the Third Nanjing Yangtze River Bridge as an example, based on the standard limit of 0.1% for the sulfur content of marine fuel, the exceeding thresholds under the most common atmospheric stability levels C to E were calculated respectively. At the same time, threshold recommendations for different monitoring plane heights and effective source heights were given to improve the expanded application of the model.

[0091] Figure 2In the figure, the X-axis represents atmospheric stability, the Y-axis represents the effective source height, the Z-axis represents the vertical distance from the monitoring height to the sea surface, the sphere represents the calculated monitoring threshold, and the color depth represents the concentration value. Taking the most common offshore working conditions as an example, the basic parameters are shown in Table 4. Under the daytime C-level stability, the recommended threshold for ship exhaust monitoring at the Nanjing Yangtze River Third Bridge at a height of 10 meters is 56.65μg·m^(-3), and under the nighttime E-level stability, the threshold is recommended to be 37.89μg·m^(-3). For monitoring heights under different bridge net heights, when the ship and other meteorological conditions do not change, the monitoring threshold is within the interval formed by the two circles. For example, when the monitoring height is 9 to 10 meters, the threshold is in the interval [88.52 56.65]μg·m^(-3), and the specific value can be solved by the model. Similarly, this conclusion also applies when any other condition changes.

[0092] Table 4 Basic parameters

[0093]

[0094]

[0095] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for determining the threshold value of ship exhaust emissions exceeding the standard that is suitable for multiple scenarios, characterized in that: The steps include: Step 1: Setting a monitoring point on the bridge to collect AIS parameters and meteorological parameters of the ship that can be monitored by the monitoring point in real time; Step 2: Analyze and process the AIS parameters and meteorological parameters of each ship through the atmospheric stability level calculation method, obtain the real-time atmospheric stability level and select the corresponding diffusion parameters; Step 3, according to the AIS parameters of the ship, obtain the ship item parameters and calculate the ship exhaust emission rate; Step 4, determine the positions of all ships that can be monitored by the monitoring point, establish a coordinate system based on the ship position and perform coordinate conversion, and calculate the concentration distribution of each ship chimney; the specific process is as follows: Step 4.1, take the projection of the exhaust gas monitoring point set on the bridge on the horizontal plane as the origin, the positive direction of the X-axis is the wind direction, the Y-axis is perpendicular to the X-axis on the horizontal plane, the positive direction is on the left side of the X-axis, and the Z-axis is located on the horizontal plane, with the upward direction as the positive direction; let the coordinates of each ship chimney be (X i , Y i , H i ), i = 1, 2, ..., n, n is the number of all ships that can be monitored at the monitoring point, X i , Y i Obtained through the ship, monitoring point latitude and longitude and wind direction, H i represents the height from the chimney of ship i to the sea level; Step 4.2, using each ship as the origin, establish different coordinate systems. The coordinates of each ship's chimney in its own coordinate system are (0, 0, H i ), assuming that the coordinates of the monitoring point P are (x, y, z), the exhaust concentration contribution of ship i to point P is C(x, y, z, H i ) is calculated as: Among them, Q i represents the exhaust emission rate of ship i, in kg / s, μ is the average wind speed, in m / s, σ y is the atmospheric diffusion coefficient on the Y axis, σ z is the atmospheric diffusion coefficient on the Z axis, x is the downwind distance in meters, y is the crosswind distance in meters; Step 4.3, set the total coordinate system, select the ship farthest from the monitoring point as the origin of the total coordinate system, and its coordinates are (X s , Y s , H s ); Step 4.4, coordinate transformation is performed on the remaining ships, and the coordinates of the remaining ships in the total coordinate system are (X i -X s , Y i -Y s , H i ); Step 4.5: Calculate the concentration distribution C of each ship at height z in the global coordinate system. i (X i -X s , Y i -Y s , z, H i ), the calculation formula is: in, represents the diffusion coefficient in the Y-axis direction; Step 5: Obtain the monitoring height according to the location of the monitoring point, and calculate the concentration threshold of the monitoring height according to the concentration distribution of each ship chimney.

2. The method for determining the threshold value of ship exhaust emissions exceeding the standard adapted to multiple scenarios according to claim 1 is characterized in that: The AIS parameters in step 1 are obtained through the AIS base station deployed at the monitoring point, and the AIS parameters include ship static parameters and ship dynamic parameters, wherein the ship static parameters include ship name, ship number and ship engine power, and the ship dynamic parameters include ship longitude, ship latitude and ship speed.

3. The method for determining the threshold value of ship exhaust emissions exceeding the standard adapted to multiple scenarios according to claim 1 is characterized in that: The meteorological parameters in step 1 are obtained by a meteorological analyzer installed at a monitoring point, and the meteorological parameters include wind speed and cloud cover.

4. The method for determining the threshold value of ship exhaust emissions exceeding the standard adapted to multiple scenarios according to claim 1 is characterized in that: The specific process of step 2 is as follows: Step 2.1, calculate the solar hour angle and solar inclination angle according to the ship's longitude and monitoring time, specifically: ω=15t+j-300 σ=(0.006918-0.399912cosθ+0.0702578sinθ-0.006758cos2θ +0.000907sin2θ-0.002697cos3θ+0.00148sin3θ)*180 / π Where, ω represents the solar hour angle; t represents the hour part of the monitoring time; j represents the ship's longitude; σ represents the solar inclination angle; d represents the ordinal number of the monitoring date in the whole year; Step 2.2, calculate the solar altitude angle, specifically: h=arcsin(sinw*sinσ+cosw*cosσ*cosω) Wherein, h represents the solar altitude angle; w represents the latitude of the ship; Step 2.3, according to the solar altitude angle, query the solar incidence level table to determine the solar incidence level; Step 2.4, according to the solar incidence level and wind speed, query the atmospheric stability level table to determine the atmospheric stability level; Step 2.5, according to the atmospheric stability level, query the diffusion parameter table to determine the atmospheric diffusion parameters.

5. The method for determining the threshold value of ship exhaust emissions exceeding the standard adapted to multiple scenarios according to claim 1 is characterized in that: In step 3, the ship parameters include the height from the ship chimney to the sea level and the ship engine power, and the specific calculation formula for the ship exhaust emission rate is: Q i =P i ×EF / 3600 Among them, Q i represents the exhaust emission rate of ship i; P i represents the engine power of ship i, kW; EF represents the emission factor of sulfur dioxide, g / (kW·h).

6. The method for determining the threshold value of ship exhaust emissions exceeding the standard adapted to multiple scenarios according to claim 1 is characterized in that: The concentration threshold of the monitoring height in step 5 is specifically: Where C represents the concentration threshold at the monitoring height, C i (X i -X s , Y i -Y s , z, H i ) represents the concentration distribution of ship i at the height z of the monitoring point P, and n is the number of all ships that can be monitored by the monitoring point.

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