Ship high-sulfur fuel oil monitoring method based on Gaussian plume model

Abstract

The invention discloses a ship high-sulfur fuel oil monitoring method based on a Gaussian plume model, and the method aims at ship flue gas remote sensing monitoring, based on the diffusion concentration of sulfur dioxide discharged by a ship at a monitoring point, an optimization algorithm is utilized, an emission source intensity inversion problem is resolved into an objective function unconstrained multi-dimensional extreme value problem, and a ship high-sulfur fuel oil monitoring result is obtained. According to the method, the emission source intensity of the ship is calculated, and the ship fuel oil consumption amount calculated by the basic information of the ship is combined, so that an underway ship fuel oil sulfur content back calculation method without the help of the carbon dioxide concentration is established, and the ship with the sulfur content exceeding the standard is effectively identified. Meanwhile, in consideration of the fact that the wind direction and the line source direction are not completely consistent in the actual navigation environment, a Gaussian plume model corrected by combining the included angle between the wind direction and the line source, the effective height of the ship flue gas emission source, the effective wind speed and the diffusion coefficient is constructed, and the accuracy of the ship high-sulfur fuel oil monitoring result is further improved.

Description

Technical Field

[0001] The invention relates to a ship smoke remote sensing monitoring method, and in particular to a ship high-sulfur fuel oil monitoring method based on a Gaussian smoke plume model. Background Art

[0002] Ship emissions are one of the major contributors to global air pollution. According to statistical analysis, ship sulfur dioxide emissions account for 4-9% of the world's total anthropogenic emissions. In order to control ship emissions, the Ministry of Transport and the Ministry of Ecology and Environment have successively issued documents such as the "Implementation Plan for Ship Air Pollutant Emission Control Areas", "Ship Engine Exhaust Pollutant Emission Limits and Measurement Methods" and "Yangtze River Economic Belt Ecological and Environmental Protection Plan", requiring that from January 1, 2020, ships entering inland river emission control areas should use marine fuel with a sulfur content of no more than 0.1% m / m. How to monitor sulfur dioxide and other pollutants emitted by ships in real time and effectively identify fuel with excessive sulfur content to maximize the role of emission control areas is an important and urgent challenge facing us at present and in the future.

[0003] Looking at the existing research at home and abroad, ship pollutant emissions and the back calculation of fuel sulfur content have attracted widespread attention, but there are still the following problems to be solved: 1) The existing fuel sulfur content identification method is mainly based on the sulfur-carbon ratio to determine the sulfur content. When it is impossible or difficult to obtain carbon dioxide monitoring concentration, it is urgent to construct a method that can identify and back calculate the sulfur content of ship fuel using only sulfur dioxide emission source strength data; 2) In the actual navigation environment, wind direction will affect the construction of the ship smoke diffusion model, especially when the wind direction is inconsistent with the navigation direction, this effect is particularly significant; 3) Due to the influence of key parameters such as the effective height of the ship smoke emission source, the diffusion coefficient, and the wind speed at the effective height of the ship emission source, the existing Gaussian diffusion model is not accurate in practical applications and urgently needs to be improved. Summary of the invention

[0004] Purpose of the invention: In order to solve the above technical problems, the present invention proposes a ship high-sulfur fuel monitoring method based on a Gaussian plume model, which has the advantages of a wide monitoring range (the optical path can monitor multiple channels simultaneously), high sensitivity (covering the monitoring limit of low concentrations from ppb to high concentrations from ppm), strong stability (not affected by the chemical behavior of the object being measured) and strong scalability.

[0005] Technical solution: In order to achieve the above-mentioned invention objectives, the present invention proposes a ship high-sulfur fuel monitoring method based on a Gaussian plume model, the method comprising: determining atmospheric stability according to weather and meteorological data, and calculating a diffusion coefficient according to atmospheric stability and downwind distance; obtaining the intensity of ship sulfur dioxide emission sources through an intelligent optimization algorithm according to the ship's dynamic and static information and the measured sulfur dioxide monitoring data of the monitoring points; calculating the ship's fuel consumption according to the basic information of the ship; calculating the ship's fuel sulfur content according to the ship's fuel consumption and the intensity of the ship's sulfur dioxide emission sources; the goal of the intelligent optimization algorithm is to make the sulfur dioxide monitoring data of each monitoring point and the corresponding sulfur dioxide calculated concentration closest, the sulfur dioxide calculated concentration is calculated based on the Gaussian plume model, and the original diffusion coefficient in the Gaussian plume model is replaced by the diffusion coefficient calculated according to the atmospheric stability and downwind distance.

[0006] Among them, the dynamic and static information of the ship includes: ship dynamic information and ship static information. The ship dynamic information includes the longitude and latitude of the ship, the ship's navigation speed, the navigation angle, and the distance from the monitoring point; the ship static information includes the water mobile communication service identification code (ship MMSI number), ship name, ship tonnage, ship type, and emission source height; weather and meteorological data include local longitude and latitude, observation time, solar hour angle, solar inclination, solar altitude angle, cloud cover, incidence level, wind speed and direction.

[0007] The Gaussian plume model can use a general conventional calculation formula that takes into account the combined influence of real sources and image sources. Considering that there will be losses in gas reflection and the diffusion concentration of the image source will be reduced, as a preferred solution, the present invention proposes a Gaussian plume model that takes into account the reflection ratio. The calculation formula for calculating the concentration of sulfur dioxide is:

[0008]

[0009] In the formula, Q represents the emission source intensity of ship smoke, σ y and σ z are the diffusion coefficients in the crosswind and vertical directions respectively; y is the crosswind coordinate; z is the vertical coordinate; H is the effective height of the ship smoke emission source, u is the effective wind speed, c is the calculated concentration of sulfur dioxide, and R is the reflection ratio, R∈[0,1].

[0010] The atmospheric stability can be determined based on weather and meteorological data, and a general atmospheric stability determination method can be used. As a preferred solution, the present invention calculates the diffusion coefficient including the following steps:

[0011] Step 21, calculate the solar hour angle according to the longitude of the monitoring point and the observation time:

[0012] ω=15t+λ-300

[0013] Where ω represents the solar hour angle, t represents the hour part of Beijing time during observation, and λ represents the geographical longitude of the monitoring point;

[0014] Step 22, calculate the solar altitude angle according to the solar hour angle, solar inclination angle and the latitude of the monitoring point:

[0015]

[0016] Where h is the solar altitude angle, represents the geographical latitude of the monitoring point, σ represents the solar inclination;

[0017]

[0018] In the formula, day indicates the day of the year when the observation time is, and θ indicates the conversion angle;

[0019] Step 23, querying the solar incidence level table according to the solar altitude angle and cloud cover data to determine the solar incidence level;

[0020] Step 24, querying the atmospheric stability level table according to the solar incidence level and wind speed data to determine the atmospheric stability;

[0021] Step 25, under different levels of atmospheric stability, determine the characteristic parameters of the crosswind direction and the vertical direction, and determine the diffusion coefficients of the crosswind direction and the vertical direction in combination with the downwind distance. The calculation formula is:

[0022]

[0023] In the formula, σ y and σ z are the diffusion coefficients in the crosswind and vertical directions, respectively, x represents the downwind distance; γ 1,y and γ 2,y is the crosswind characteristic parameter; γ 1,z and γ 2,z is the vertical characteristic parameter; α y and α z is the diffusion index.

[0024] The goal of the intelligent optimization algorithm is to make the sulfur dioxide monitoring data of each monitoring point and the corresponding sulfur dioxide calculated concentration closest to each other. Any functional relationship that substantially reflects the sulfur dioxide monitoring data of each monitoring point and the corresponding sulfur dioxide calculated concentration closest to each other can be used. As a preferred solution, the objective function of the intelligent optimization algorithm is set as:

[0025]

[0026] In the formula, and are the sulfur dioxide monitoring data of the ith monitoring point and the corresponding calculated sulfur dioxide concentration, n is the number of monitoring points; the objective function f(Q) is the objective function, and Q represents the emission source intensity of ship smoke.

[0027] Furthermore, the present invention also improves the Gaussian plume model, including:

[0028] The angle between the wind direction and the line source is corrected. When the angle between the wind direction and the line source is ɑ, the calculation formula for sulfur dioxide concentration is improved to the integral formula of Gaussian plume diffusion of ship smoke:

[0029]

[0030] Where, C is the improved calculated concentration of sulfur dioxide; (x p ,y p ) is the coordinate of the monitoring point; (0, y′) is the coordinate of the ship’s position; α is the angle between the wind direction and the line source; Q represents the emission source intensity of the ship’s smoke, α y and σ z are the diffusion coefficients in the crosswind and vertical directions respectively; z is the vertical coordinate; H is the effective height of the ship smoke emission source, u is the effective wind speed, R is the reflection ratio, R∈[0,1], and L is the line source length.

[0031] Correction for the effective height of ship smoke emission sources:

[0032] H=H′+Δh

[0033] Where H′ is the geometric height of the ship chimney; Δh is the smoke lift height of the ship.

[0034] Correction for effective wind speed:

[0035]

[0036] In the formula, u g H is the ground wind speed monitored by the meteorological instrument; g is the height at which the meteorological instrument monitors wind speed; m is the power law constant determined by the atmospheric stability.

[0037] Based on the basic information of the ship, the common method for calculating the fuel consumption of the ship is:

[0038] Step 41, determine the fuel consumption of the main engine of the ship:

[0039] A 1 =a 1 *b 1

[0040] In the formula, A 1 is the fuel consumption of the main engine; a 1is the host power; b 1 is the fuel consumption rate of the main engine;

[0041] Step 42, determine the fuel consumption of the auxiliary engine of the ship:

[0042] A 2 =a 2 *b 2

[0043] In the formula, A 2 is the auxiliary engine fuel consumption; a 2 is the auxiliary machine power; b 2 is the auxiliary engine fuel consumption rate;

[0044] Step 43, determine the fuel consumption of the ship:

[0045]

[0046] Where M is the fuel consumption of the ship; p is the basic fuel consumption coefficient of the main engine.

[0047] This common method can be replaced by other schemes for calculating ship fuel consumption.

[0048] As a preferred solution, the sulfur content of the ship fuel is calculated according to the ship fuel consumption and the ship sulfur dioxide emission source intensity, and the calculation formula is:

[0049]

[0050] Where S is the sulfur content of ship fuel.

[0051] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following advantages: The method of the present invention is based on the diffusion concentration of sulfur dioxide emitted by ships at the monitoring point, uses the Gaussian plume model to explore the diffusion process of ship smoke, and reduces the emission source intensity inversion problem to the unconstrained multidimensional extreme value problem of the objective function, and uses the intelligent optimization algorithm to infer the emission source intensity of the ship. Combined with the ship fuel consumption calculated from the basic information of the ship, a method for inverse calculation of the sulfur content of fuel oil of ships at sea without the help of carbon dioxide concentration is constructed, which effectively helps the maritime department to identify high-sulfur oil suspected ships remotely and quickly without boarding the ship. This method can avoid the problems of low efficiency and small monitoring range of traditional regulatory means, solve the problems of narrow coverage of existing monitoring methods, reliance on carbon dioxide monitoring data, and difficulty in obtaining the required parameters in the calculation process. At the same time, it overcomes the influence of factors such as wind direction and speed, effective height of ship smoke emission source, and diffusion coefficient on the construction of ship smoke diffusion model. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a calculation flow chart of the ship high sulfur fuel monitoring method based on the Gaussian plume model described in the present invention;

[0053] Figure 2 Schematic diagram of the Gaussian plume model in the method of the present invention. DETAILED DESCRIPTION

[0054] In order to more clearly illustrate the technical solution of the embodiment of the present invention, it will be introduced in detail below in conjunction with the accompanying drawings.

[0055] like Figure 1 As shown, it is a calculation flow chart of the ship high sulfur fuel monitoring method based on the Gaussian plume model of the present invention, and the specific steps are as follows:

[0056] Step 1: construct a Gaussian plume model based on the dynamic and static information of the ship received by the ship automatic identification system (AIS), the sulfur dioxide monitoring data measured by the ship, and the weather and meteorological data;

[0057] In step 1, the ship dynamic information includes the latitude and longitude of the ship, the ship's navigation speed, the navigation angle, and the distance from the monitoring point; the ship static information includes the water mobile communication service identification code (ship MMSI number), ship name, ship tonnage, ship type, emission source height, that is, the distance between the top of the exhaust pipe and the water surface; weather and meteorological data include wind speed and wind direction.

[0058] The specific process of step 1 is as follows:

[0059] Step 11: The smoke diffusion concentration of any ship at any point is affected by both the real source and the image source, and a real source diffusion model is constructed:

[0060]

[0061] In the formula, c s is the real source diffusion concentration, kg / m 3 ; Q represents the emission source intensity of ship smoke, kg / s; σ y and σ z are the diffusion coefficients in the y and z directions, i.e., the crosswind direction and the vertical direction, respectively; y is the crosswind coordinate; z is the vertical coordinate; H is the effective height of the ship's smoke emission source, m; u is the effective wind speed, m / s;

[0062] Step 12: Construct image source diffusion model:

[0063]

[0064] In the formula, c s ′ is the image source diffusion concentration, kg / m 3 ; R is the reflection ratio. Considering that there will be losses in gas reflection, the diffusion concentration of the image source will decrease, so R∈[0,1];

[0065] Step 13, combining the real source diffusion model and the image source diffusion model to construct a Gaussian plume model:

[0066]

[0067] Where c is the cumulative diffusion concentration, kg / m 3 .

[0068] Step 2: Determine the atmospheric stability based on the local latitude and longitude, observation time, solar hour angle, solar inclination, solar altitude angle, cloud cover, incident level, wind speed and other factors, and determine the diffusion coefficient in combination with the downwind distance. The specific method is as follows:

[0069] Step 21, calculate the solar hour angle according to the longitude of the monitoring point and the observation time:

[0070] ω=15t+λ-300

[0071] Where ω represents the solar hour angle, t represents the hour part of Beijing time during observation, and λ represents the geographical longitude of the monitoring point;

[0072] Step 22, calculate the solar altitude angle according to the solar hour angle, solar inclination angle and the latitude of the monitoring point:

[0073]

[0074] Where h is the solar altitude angle, represents the geographical latitude of the monitoring point, σ represents the solar inclination;

[0075]

[0076] In the formula, day indicates the day of the year when the observation time occurs;

[0077] Step 23, according to the solar altitude angle and cloud cover data, query the solar incidence level table (as shown in Table 1) to determine the solar incidence level;

[0078] Table 1 Solar incidence levels

[0079]

[0080] Step 24, according to the solar incidence level and wind speed data, query the atmospheric stability level table (as shown in Table 2) to determine the atmospheric stability. The atmospheric stability is divided into AF levels, namely: A strong instability, B unstable, C weak instability, D neutral, E relatively stable, F stable;

[0081] Table 2 Atmospheric stability levels

[0082]

[0083] Step 25, determine the diffusion coefficient σ in the crosswind direction and vertical direction at different levels of atmospheric stability y and σ z The functional relationship with the downwind distance x is used to determine the diffusion coefficient in the crosswind and vertical directions in combination with the downwind distance:

[0084]

[0085] Where x represents the distance from the emission source in the downwind direction, i.e., the downwind distance, m; γ 1,y and γ 2,y is the crosswind characteristic parameter; γ 1,z and γ 2,z is the vertical characteristic parameter; α y and α z is the diffusion index. The above parameter values ​​can be obtained through the Briggs diffusion coefficient equation (as shown in Table 3).

[0086] Table 3 Briggs diffusion coefficient values

[0087] Atmospheric stability <![CDATA[γ 1,y ]]> <![CDATA[γ 2,y ]]> <![CDATA[α y ]]> <![CDATA[γ 1,z ]]> <![CDATA[γ 2,z ]]> <![CDATA[α z ]]> A——Strong instability 0.22 0.0001 0.5 0.20 0 1.0 B——Unstable 0.16 0.0001 0.5 0.12 0 1.0 C——Weakly unstable 0.11 0.0001 0.5 0.08 0.0002 0.5 D——Neutral 0.08 0.0001 0.5 0.06 0.0015 0.5 E——More stable 0.06 0.0001 0.5 0.03 0.0003 1.0 F——Stable 0.04 0.0001 0.5 0.02 0.0003 1.0

[0088] Step 3: Combine the wind direction and line source angle, the effective height of the ship's smoke emission source, the effective wind speed and other factors to build a Gaussian plume correction model, and use the intelligent optimization algorithm to reduce the emission source intensity inversion problem to the unconstrained multidimensional extreme value problem of the objective function, and estimate the sulfur dioxide emission source intensity of the ship. The specific method is as follows:

[0089] Step 31, correct the angle between the wind direction and the line source. In the actual navigation environment, the wind direction and the line source direction are not completely consistent, and the angle between the two will affect the construction of the ship smoke diffusion model. Therefore, when the angle between the wind direction and the line source is α, Figure 2 As shown, the emission concentration of the line source in the crosswind direction is the same. The finite length of the moving emission source along the horizontal direction can be divided into n equal parts, and the concentration of all points on the finite length relative to any point downwind can be integrated and summed.

[0090] exist Figure 2 In the above equation, P(x p ,y p ) is the coordinate of the monitoring point; A(0,y′) is the coordinate of the ship's position; α is the angle between the wind direction and the line source. The diffusion of ship smoke is divided into two parts, one part moves along the direction of the ship's travel, and the other part moves along the wind direction under the influence of wind speed. The vector synthesis of wind direction and speed and ship heading speed is the actual diffusion direction of ship smoke. W Axis, with the direction perpendicular to the wind direction as Y W Axis, make Y through point A and point P WThe perpendicular line of the axis intersects at point A′ and point B′, then the ship position and the monitoring point position are projected on the Y W The distance on the axis is A'B'. Draw a perpendicular line to the Y axis through point P and intersect it at point C. Draw a parallel line to A'B' through point C, intersecting AA' at point A", PB' at point B", ∠PCB" = ∠CAA" = α. Then:

[0091] A′B′=A″B″=AC·sinα+PC·cosα=(y p -y′)sinα+x p cosα

[0092] In addition, when estimating the pollutant concentration caused by a finite line source, the "edge effect" caused by the end of the line source must be taken into account. For a crosswind finite line source, if the range of the line source extends from -L to L, the finite line source diffusion model integrates the variable y' from -L to L. Therefore, when the angle between the wind direction and the line source is α, the integral formula for ship smoke diffusion is:

[0093]

[0094] Where C is the diffusion concentration of the Gaussian plume model, kg / m 3 ;

[0095] Step 32, correcting the effective height of the ship smoke emission source:

[0096] H=H′+Δh

[0097] In the formula, H′ is the geometric height of the ship chimney, m; Δh is the smoke lift height of the ship, m. Among them, the smoke lift height is related to many parameters such as buoyancy parameters, the distance from a certain point in the downwind direction to the emission source, ship speed, emission source temperature, ambient atmospheric temperature, and emission port diameter. Since some parameters are difficult to obtain and are limited by the lack of actual data, the smoke lift height can adopt the following recommended values. When the geometric height of the emission chimney is greater than 50m, the recommended value of the smoke lift height is 15m; when the chimney height is between 30 and 50m, the lift height is 8m; when the chimney height is less than 30m, the lift height is 5m. If in an actual case, the geometric height of the ship chimney is small and the ambient wind speed is large, the linear interpolation method can be used to determine the smoke lift height;

[0098] Step 33, perform effective wind speed correction:

[0099]

[0100] In the formula, u g is the ground wind speed monitored by the meteorological instrument, m / s; H g is the height of the meteorological instrument monitoring wind speed, m; m is the power law constant, determined by the atmospheric stability, as shown in Table 4:

[0101] Table 4 Values ​​of power law constants under different atmospheric stability conditions

[0102]

[0103] Step 34, using the intelligent optimization algorithm, the intensity of the sulfur dioxide emission source of the ship is estimated:

[0104]

[0105] In the formula, and are the i-th monitored concentration and calculated concentration respectively; the objective function f(Q) is the sum of squares of the errors between the monitored concentration and the calculated concentration at each monitoring point.

[0106] Taking the genetic algorithm to solve the above unconstrained minimum optimization problem as an example, the parameters in the problem are encoded as chromosomes, and the chromosome individuals in the population are updated by selection, crossover, mutation and other operations in an iterative manner to achieve the evolution from the initial solution to the optimal solution of the inverse problem, and finally form the chromosome that best meets the optimization goal. The specific steps are: 1) Encoding. Compile the solution data of the problem solution space into genotype string structure data; 2) Generate the initial population. Randomly generate N initial string structures containing source strength information as the starting point of evolution; 3) Fitness function. Substitute the individuals in the population into the objective function, calculate the chromosome individual values ​​and sort them; 4) Selection. According to the law of survival of the fittest, select excellent individuals from the current population; 5) Crossover. Randomly perform crossover operations between different individuals to generate new individuals and new populations; 6) Mutation. Select a small number of individuals in the population, change the string structure with a given probability, and jump out of the local optimum; 7) Iteration end condition. Specify the maximum number of iterations, iteration time and other conditions to terminate this iteration.

[0107] Step 4: Calculate the fuel consumption of the ship based on the basic information of the ship. The specific process is as follows:

[0108] Step 41, determine the fuel consumption of the main engine of the ship:

[0109] A 1 =a 1 *b 1

[0110] In the formula, A 1 is the fuel consumption of the main engine, kg / h; a 1 is the main engine power, kw; b 1 is the main engine fuel consumption rate, kg / kw·h, and the value range of the main engine fuel consumption rate is 0.165~0.178kg / kw·h;

[0111] Step 42, determine the fuel consumption of the auxiliary engine of the ship:

[0112] A 2 =a 2 *b 2

[0113] In the formula, A 2 is the auxiliary engine fuel consumption, kg / h; a 2 is the auxiliary machine power, kw; b 2 is the auxiliary engine fuel consumption rate, kg / kw·h, and the auxiliary engine fuel consumption rate ranges from 0.019 to 0.025 kg / kw·h. For ships with missing main engine power and auxiliary engine power data, they can be obtained based on AIS static information and ship gross tonnage data in the Lloyd's Register database using multi-source data matching and regression fitting methods, as shown in Table 5:

[0114] Table 5 Relationship between ship gross tonnage and main engine power and auxiliary engine power

[0115]

[0116]

[0117] Step 43, determine the fuel consumption of the ship:

[0118]

[0119] Where M is the fuel consumption of the ship, kg / s; p is the basic fuel consumption coefficient of the main engine, which is 0.7 for liquefied gas tankers, 0.8-0.9 for cargo ships, 0.8-0.9 for container ships, 0.5-0.7 for tugboats, and 1.0 for passenger ships.

[0120] Step 5: Calculate the sulfur content of ship fuel by the ratio of sulfur dioxide emission source intensity to ship fuel consumption. The specific process is as follows:

[0121] The sulfur content of ship fuel can be expressed as the ratio of sulfur dioxide emission rate (i.e. emission source strength) to ship fuel consumption. 2 The molecular mass ratio of sulfur to elemental sulfur S is 64:32=2:1, so the sulfur content of ship fuel is:

[0122]

[0123] Where S is the sulfur content of ship fuel, %.

[0124] At around 10:06 am on December 25, 2021, the monitoring section of Nanjing Third Bridge in Nanjing City, Jiangsu Province detected a sulfur dioxide concentration of 51.5 μg / m 3After calculation, it was determined that the ship exceeded the standard and an alarm was issued. After reporting to the Jiangsu Maritime Safety Department, the staff immediately boarded the ship with portable analytical instruments to extract oil samples for testing and confirmed that the sulfur content of the ship's fuel exceeded the standard. The specific calculation and analysis process is as follows:

[0125] (1) Determine atmospheric stability

[0126] The longitude of Nanjing Third Bridge is 118.6261 and the latitude is 31.9614. Then t = 10, day = 359, λ = 118.6261, Combining the cloud cover data and wind speed conditions, the atmospheric stability is obtained to be level D, which is a neutral state.

[0127] (2) Determine the intensity of ship emission sources

[0128] First, determine the diffusion coefficient, the effective height of the ship smoke emission source and the wind speed correction coefficient at the effective height. In this embodiment, the downwind distance x = 809.9m, and the diffusion coefficient can be obtained as σ y =62.3179,σ z =32.6529. The ship in this embodiment is a small bulk carrier with a chimney height of about 7m. After linear interpolation, the smoke lift height is taken as 1m. Therefore, the effective height of the ship's smoke emission source is corrected to 8m. For the effective wind speed correction, the ground wind speed monitored by the meteorological instrument is 2.7m / s, and the height at which the meteorological instrument monitors the wind speed is about 10m. From the D-level atmospheric stability, it can be seen that the power law constant in non-urban areas is 0.15, and the wind speed at the effective height of the ship's smoke emission source is corrected to 2.61m / s. According to the coverage of the monitoring equipment and the ship's smoke diffusion characteristics, the length of the limited line source is 1km, that is, L is 500m.

[0129] Genetic algorithm is used to solve the emission source strength. The specific process is as follows: 1) Encoding. For the sulfur dioxide emission source strength Q and the distance from the ship to the bridge L 0 (ship position) is encoded with real numbers; 2) Generate the initial population. First, set the population size to 20 (two unknown quantities Q and L 0 Each set 10 individuals), which are randomly generated by the initial population generation function; 3) Fitness function. Calculate the sum of squares of the monitored concentration and the calculated concentration of sulfur dioxide on the ship, where the objective function is the sum of squares of the errors of each monitored concentration and the calculated concentration; 4) Selection, crossover, and mutation operations. Operate on the individuals in the group, continuously complete the replacement process of the old and new populations, realize the global search of the genetic algorithm, and achieve the iterative process of the optimal source strength information solution; 5) Set the maximum evolutionary generation to 500 generations and the termination generation to 150 generations. For the new population, repeat step 4 until the iterative result of the genetic algorithm meets the termination condition. At this time, the individual with the highest fitness in the new generation is the global optimal solution, and the result is output.

[0130] In this embodiment, the genetic algorithm stops after 72 iterations, and the sulfur dioxide emission source intensity Q=146212 μg / s, that is, 0.146 g / s, is obtained.

[0131] (3) Determine the sulfur content of fuel

[0132] Combined with the ship type database information, the gross tonnage of the small bulk carrier is 550t. The main engine power is 615kw and the auxiliary engine power is 156kw according to Table 5. The basic fuel consumption coefficient p of the main engine is 0.8, the fuel consumption rate of the main engine is 0.172kg / kw·h, and the fuel consumption rate of the auxiliary engine is 0.022kg / kw·h. The ship fuel consumption M can be obtained to be 88.056kg / h, that is, 24.460g / s.

[0133] Finally, the sulfur content S of the ship's fuel was calculated to be 0.298%. After the staff boarded the ship to take oil samples for testing, it was confirmed that the actual sulfur content of the ship's fuel was 0.26%. The calculation result of this method has an accuracy of 85.38%. The above calculation results show that this method can accurately monitor and identify ships using high-sulfur fuel without relying on carbon dioxide concentration.

Claims

1. A method for monitoring ship high-sulfur fuel oil based on a Gaussian plume model, characterized in that: The method comprises: determining atmospheric stability according to weather and meteorological data, and calculating a diffusion coefficient according to atmospheric stability and downwind distance; obtaining the intensity of sulfur dioxide emission sources of the ship through an intelligent optimization algorithm according to dynamic and static information of the ship and measured sulfur dioxide monitoring data of monitoring points; calculating the fuel consumption of the ship according to basic information of the ship; and calculating the sulfur content of the fuel of the ship according to the fuel consumption of the ship and the intensity of sulfur dioxide emission sources of the ship; the goal of the intelligent optimization algorithm is to make the sulfur dioxide monitoring data of each monitoring point and the corresponding calculated sulfur dioxide concentration closest, the calculated sulfur dioxide concentration is calculated based on a Gaussian plume model, and the original diffusion coefficient in the Gaussian plume model is replaced by the diffusion coefficient calculated according to atmospheric stability and downwind distance.

2. The method for monitoring ship high sulfur fuel oil based on Gaussian plume model according to claim 1, characterized in that: The dynamic and static information of the ship includes: ship dynamic information and ship static information. The ship dynamic information includes the longitude and latitude of the ship, the ship's navigation speed, the navigation angle, and the distance from the monitoring point; the ship static information includes the water mobile communication service identification code, ship name, ship tonnage, ship type, and emission source height; weather and meteorological data include local longitude and latitude, observation time, solar hour angle, solar inclination, solar altitude angle, cloud cover, incidence level, wind speed and direction.

3. The method for monitoring ship high sulfur fuel oil based on Gaussian plume model according to claim 1, characterized in that: The Gaussian plume model is used to calculate the sulfur dioxide concentration. The calculation formula is: In the formula, Q represents the emission source intensity of ship smoke, σ y and σ z are the diffusion coefficients in the crosswind and vertical directions respectively; y is the crosswind coordinate; z is the vertical coordinate; H is the effective height of the ship smoke emission source, u is the effective wind speed, c is the calculated concentration of sulfur dioxide, and R is the reflection ratio, R∈[0,1].

4. The method for monitoring ship high sulfur fuel oil based on Gaussian plume model according to claim 1, characterized in that: The atmospheric stability is determined based on weather and meteorological data, and the diffusion coefficient is calculated based on the atmospheric stability and downwind distance, including the following steps: Step 21, calculate the solar hour angle according to the longitude of the monitoring point and the observation time: ω=15t+λ-300 Where ω represents the solar hour angle, t represents the hour part of Beijing time during observation, and λ represents the geographical longitude of the monitoring point; Step 22, calculate the solar altitude angle according to the solar hour angle, solar inclination angle and the latitude of the monitoring point: Where h is the solar altitude angle, represents the geographical latitude of the monitoring point, σ represents the solar inclination; In the formula, day indicates the day of the year when the observation time is, and θ indicates the conversion angle; Step 23, querying the solar incidence level table according to the solar altitude angle and cloud cover data to determine the solar incidence level; Step 24, querying the atmospheric stability level table according to the solar incidence level and wind speed data to determine the atmospheric stability; Step 25, under different levels of atmospheric stability, determine the characteristic parameters of the crosswind direction and the vertical direction, and determine the diffusion coefficients of the crosswind direction and the vertical direction in combination with the downwind distance. The calculation formula is: In the formula, σ y and σ z are the diffusion coefficients in the crosswind and vertical directions, respectively, x represents the downwind distance; γ 1,y and γ 2,y is the crosswind characteristic parameter; γ 1,z and γ 2,z is the vertical characteristic parameter; α y and α z is the diffusion index.

5. The method for monitoring ship high sulfur fuel oil based on Gaussian plume model according to claim 1, characterized in that: The objective function of the intelligent optimization algorithm is: In the formula, and are the sulfur dioxide monitoring data of the ith monitoring point and the corresponding calculated sulfur dioxide concentration, n is the number of monitoring points; the objective function f(Q) is the objective function, and Q represents the emission source intensity of ship smoke.

6. The method for monitoring ship high sulfur fuel oil based on Gaussian plume model according to claim 1, characterized in that: The Gaussian plume model is improved, including: correcting the angle between the wind direction and the line source. When the angle between the wind direction and the line source is a, the calculation formula for calculating the concentration of sulfur dioxide is improved to the integral formula for the diffusion of the Gaussian plume of ship smoke: Where, C is the improved calculated concentration of sulfur dioxide; (x p ,y p ) is the coordinate of the monitoring point; (0, y′) is the coordinate of the ship’s position; α is the angle between the wind direction and the line source; Q represents the emission source intensity of the ship’s smoke, σ y and σ z are the diffusion coefficients in the crosswind and vertical directions respectively; z is the vertical coordinate; H is the effective height of the ship smoke emission source, u is the effective wind speed, R is the reflection ratio, R∈[0,1], and L is the line source length.

7. The method for monitoring ship high sulfur fuel oil based on Gaussian plume model according to claim 1, characterized in that: The Gaussian plume model is improved, including: correcting the effective height of the ship smoke emission source: H=H′+Δh Where H′ is the geometric height of the ship chimney; Δh is the smoke lift height of the ship.

8. The method for monitoring ship high sulfur fuel oil based on Gaussian plume model according to claim 1, characterized in that: The Gaussian plume model is improved, including: correcting the effective wind speed: In the formula, u g H is the ground wind speed monitored by the meteorological instrument; g is the height at which the meteorological instrument monitors wind speed; m is the power law constant determined by the atmospheric stability.

9. The method for monitoring ship high sulfur fuel oil based on Gaussian plume model according to claim 1, characterized in that: Calculate the fuel consumption of the ship based on the basic information of the ship, including the following steps Step 41, determine the fuel consumption of the main engine of the ship: A1=a1*b1 In the formula, A1 is the main engine fuel consumption; a1 is the main engine power; b1 is the main engine fuel consumption rate; Step 42, determine the fuel consumption of the auxiliary engine of the ship: A2=a2*b2 In the formula, A2 is the auxiliary engine fuel consumption; a2 is the auxiliary engine power; b2 is the auxiliary engine fuel consumption rate; Step 43, determine the fuel consumption of the ship: Where M is the fuel consumption of the ship; p is the basic fuel consumption coefficient of the main engine.

10. The method for monitoring ship high sulfur fuel oil based on Gaussian plume model according to claim 1, characterized in that: According to the fuel consumption of the ship and the intensity of the sulfur dioxide emission source of the ship, the sulfur content of the fuel of the ship is calculated as follows: Where S is the sulfur content of ship fuel.

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