Calculation method for carbon emission of trailing suction dredger

Abstract

The invention discloses a method for calculating carbon emission of a trailing suction dredger. The method comprises the steps that S1, the shaft power of a dredge pump is calculated; s2, calculating the shaft power of the high-pressure flushing pump; s3, calculating the main propulsion power of the trailing suction dredger; s4, drag head resistance power is calculated; step S5, forming a ship total power calculation model according to the power calculation results of the step S1 to the step S4, inputting a construction state, process parameters, a construction section and construction time, calculating the instantaneous total power of the ship, and further calculating carbon emission; s6, integrating the calculation model, and calculating the carbon emission of the construction period; s7, the construction periods of different construction sections of the channel are measured and calculated; and S8, arranging different ships for construction in different construction sections according to the calculated construction periods of the different construction sections, and calculating the comprehensive total carbon emission of the fleet in the different construction sections. The dredging efficiency is greatly improved, the energy consumption is reduced, and the carbon emission is reduced.

Description

Technical Field

[0001] The present invention relates to a method for calculating carbon emissions of a trailing suction hopper dredger. Background Art

[0002] According to the 2021 global carbon dioxide emissions statistics report of the International Energy Agency (IEA), the global energy-related CO 2 emissions reached 36.3 billion tons, hitting a record high. According to statistics, the top five carbon-emitting industries in China are power and heat, manufacturing and construction, industry, transportation, and agriculture. In recent years, significant achievements have been made in carbon accounting and emission reduction measures for high-carbon-emitting industries in China.

[0003] There have been many studies on regional carbon emissions at scales such as global, national, provincial, major function areas, counties and cities, and grids, mostly from a single perspective such as land use, industry, and energy. Research on carbon emission space, such as carbon emission differences between cities, carbon budgets, and carbon spillover, mostly focuses on a relatively large research scope, lacking comprehensive accounting of carbon emissions within small-scale estuary regions and research on their spatial differentiation. Currently, there are only a few cases for reference in relevant research on carbon emissions in the Yangtze Estuary at home and abroad. Therefore, the accounting of carbon emissions in the Yangtze Estuary dredging industry and research on their spatial distribution are very insufficient.

[0004] As the main vessel in the dredging construction industry, the trailing suction hopper dredger has technical characteristics such as self-loading, self-navigation, self-unloading, flexibility, strong resistance to wind and waves, and the ability to discharge dredged spoil into land reclamation areas. Therefore, it is widely used in engineering fields such as port and waterway excavation and maintenance. The traditional construction process of the trailing suction hopper dredger, namely "dig, transport, and dump", is relatively mature. Facing complex construction conditions, a huge construction machinery operation system, and a large number of dynamic construction parameters, optimizing the selection of appropriate construction processes according to different engineering characteristics can not only greatly improve the dredging efficiency, but also reduce energy consumption and carbon emissions.

[0005] Therefore, a method for calculating carbon emissions of a trailing suction hopper dredger is provided. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for calculating carbon emissions of a trailing suction hopper dredger to greatly improve the dredging efficiency, reduce energy consumption, and reduce carbon emissions.

[0007] The technical solution for achieving the above purpose is as follows: A method for calculating carbon emissions of a trailing suction hopper dredger includes: Step S1, calculating the shaft power of the mud pump; Step S2, calculating the shaft power of the high-pressure flushing water pump; Step S3, calculating the main propulsion power of the trailing suction hopper dredger; Step S4, calculating the resistance power of the dredging head; Step S5: According to the power calculation results of Steps S1 - S4, form a total ship power calculation model, input the construction status, process parameters, construction section, and construction time, calculate the instantaneous total power of the ship, and then calculate the carbon emissions. Step S6: Integrate the calculation model to calculate the carbon emissions during the construction period. Step S7: Measure the construction periods of different construction sections of the waterway. Step S8: According to the measured construction periods of different construction sections, arrange different ships for construction in different construction sections, and calculate the total comprehensive carbon emissions of the fleet in different construction sections.

[0008] Preferably, in Step S1, the calculation process of the shaft power of the slurry pump is as follows: Calculate the shaft power of the slurry pump according to the calculated effective power of the slurry pump and the actual pump efficiency. The calculation formula is as follows: ; In the formula, P 有效 is the effective power of the slurry pump, H is the head of the slurry pump, Q 1 is the displacement of the slurry pump, ρ is the density of the slurry, and g is the acceleration due to gravity; Among them, ; In the formula, V is the flow velocity, and r is the radius of the discharge pipe of the slurry pump; ; In the formula, V 2 is the discharge port flow velocity, V 1 is the suction port flow velocity, P 2 is the discharge port pressure, P 1 is the suction pressure, and h is the vertical height distance between the discharge port pressure gauge and the center of the suction port of the slurry pump; The head of the slurry pump includes four parts: one is the velocity head, the second is the pressure head, the third is the elevation head, and the fourth is the frictional resistance loss and the elbow resistance loss. Among them, ; In the formula, K 1 and both K 2 are resistance coefficients, L is the straight pipe length of the slurry pipe, D is the inner diameter of the straight pipe of the slurry pipe, and g is the acceleration due to gravity; According to the flow - efficiency curve fitting formula, the actual pump efficiency is empirically selected as 0.8 of the theoretical pump efficiency, that is: ; In the formula, η 实际 is the actual pump efficiency of the slurry pump, η 理论It is the theoretical pump efficiency of the mud pump, obtained from the flow - efficiency curve fitting formula in the clear water test, and the flow velocity is the direct acquisition reading of the ship flowmeter.

[0009] Preferably, in the step S2, the calculation process of the shaft power of the high - pressure flushing water pump is as follows: Statistics on the rotation speed, pressure, and power of the high - pressure water pump, draw the characteristic curves of the high - pressure water pump at different rotation speeds. The characteristic curves include the flow velocity - rotation speed - head curve, the flow velocity - rotation speed - power curve, and the flow velocity - rotation speed - efficiency curve, and fit to obtain the formula; Determine the flow rate according to the flow velocity of the high - pressure water pump, that is: ; In the formula, V G is the flow velocity of the high - pressure water pump, S G is the area of the discharge pipe diameter of the high - pressure water pump, r G is the radius of the discharge pipe of the high - pressure water pump, R G is the diameter of the discharge pipe of the high - pressure water pump; According to the flow velocity and combined with the flow velocity - rotation speed - head curve, obtain: ; Determine the pump efficiency discount ratio F according to the actual pressure and the theoretical pressure; ; Calculate the theoretical pressure at different rotation speeds, take the ratio with the actual pressure, obtain the pump efficiency discount ratio F at different rotation speeds, and average to get the pump efficiency discount ratio, that is: ; In the formula, F a is the pump efficiency discount ratio of the a - th group of rotation speeds, and a is the number of rotation speed groups; Determine the pipeline characteristics according to the flow rate and the actual pressure, that is: The total resistance of the pipeline system consists of the following two parts: ; Among them, H G静 is the static head of the elevation difference between the inlet and outlet of the pipeline, and the loss head H G损失 includes the frictional loss along the way and the local resistance loss, which is proportional to the square of the flow rate Q 2 , that is: ; In the formula, k is the pipeline characteristic coefficient; Furthermore, establish the pipeline characteristic equation. Assume H G静 =h, the energy difference generated by the fluid in the pipeline system due to the vertical height difference between the inlet and outlet, that is: ; The actual working point of the pump satisfies: ; Subtract the static head h from the H in each group to obtain the corrected head: 泵i ; ; Fit and calculate the pipeline characteristic coefficient k. Use the least squares method to fit the data to obtain the pipeline characteristic coefficient k: ; In the formula, Q 2i is the flow rate at different rotational speeds of the high-pressure water pump, and H 泵i is the head at different rotational speeds of the high-pressure water pump; Calculate the corresponding flow rate according to different pressures and pipeline characteristics. Determine the theoretical efficiency by looking up the table based on the corresponding flow velocity. Determine the actual pump efficiency according to the theoretical efficiency and the pump efficiency discount ratio. Determine the effective power according to the pressure and flow rate. Determine the actual shaft power according to the effective power and the actual pump efficiency, that is: ; That is: ; In the formula, P G实功 is the actual power of the high-pressure water pump, η G实际 is the actual pump efficiency of the high-pressure water pump, and η G理论 is the theoretical pump efficiency of the high-pressure water pump.

[0010] Preferably, in step S3, the calculation process of the main propulsion power of the trailing suction hopper dredger is as follows: According to the principle of physics, in ship propulsion, the propulsion power is used to overcome the resistance of the ship to make the ship move forward. When the ship is sailing at a constant speed, the propulsive force is equal to the resistance of the ship, that is: ; That is: ; In the formula, P C is the main propulsion power of the trailing suction hopper dredger, R is the resistance of the trailing suction hopper dredger, V C is the speed of the trailing suction hopper dredger, R f is the frictional resistance, R w is the wave-making resistance, and R s is the form resistance; Among them, The frictional resistance R f is proportional to , that is: ; To simplify the calculation, set the frictional resistance coefficient i, which is related to the hull roughness, wetted surface area, and Reynolds number, For the trailing suction hopper dredger, the empirical value of the friction resistance coefficient i is 0.35 - 0.50; For low-speed ships, the wave-making resistance R w accounts for a relatively small proportion of the total resistance. For high-speed ships, the wave-making resistance R w becomes the main resistance component. When the ship speed exceeds the critical value, the wave-making resistance increases sharply, and its growth rate is much faster than that of the friction resistance, being proportional to the square or higher power of the ship speed, i.e.: ; In the formula, n ≥ 2, and n takes 3; To simplify the calculation, a wave-making resistance coefficient j is set such that For the wave-making resistance coefficient j of the trailing suction hopper dredger, the empirical value is 0.03 - 0.06; The ITTC empirical formula is used to calculate the form resistance R s , i.e.: ; The Holtrop formula is used to calculate the wetted surface area S of the hull C : ; In the formula, ρ 1 is the density of water, S C is the wetted surface area of the hull, C DS is the form resistance coefficient, B is the beam of the ship, T is the draft, C B is the block coefficient of the ship, and L 1 is the length of the ship; The calculation formula for the block coefficient of the ship is as follows: ; In the formula, is the displacement volume, and Δ is the full load displacement; Furthermore, it is obtained that: ; In the formula, i is the friction resistance coefficient and j is the wave-making resistance coefficient; Finally, it is obtained that: .

[0011] Preferably, in the step S4, the calculation process of the drag power of the drag head is as follows: Obtain the main engine power, auxiliary engine power, and corresponding construction parameters of the ship in different sections and at different times; According to the main engine and auxiliary engine powers, deduct the calculated values of the mud pump, high-pressure flushing, and propulsion power to obtain the power corresponding to the drag head and drag arm resistances, and establish a relationship with the dredging speed, i.e.: ; Calculate P 耙阻功 , corresponding to the dredging speed V C , plot the curve, and establish the fitting relationship between P 耙阻功 and the ship speed: ; In the formula, P 主瞬 is the instantaneous total power of the ship, P 辅发 is the auxiliary engine power, η is the efficiency of the trailing suction dredger, P 辅助 is the power of the ship's auxiliary equipment, and a, b, and c are all fitting parameters of P 耙阻功 and the ship speed.

[0012] Preferably, in step S5, input the construction state, process parameters, construction section, and construction time into the calculation model, calculate the instantaneous total power of the ship, and then calculate the carbon emissions, that is: The instantaneous total power of the ship P 主瞬 : ; Each ship refers to the fuel consumption at 50%, 75%, 80%, and 100% loads during the main engine bench test. When the instantaneous total power falls within a certain range of the main engine power, use the instantaneous fuel consumption rate in this range. The instantaneous emission time is t, then: ; In the formula, M 1 is the fuel consumption, and F is the fuel consumption rate; Calculate the instantaneous carbon emissions according to the carbon dioxide emission coefficient table CFj: Fuel mode: ; Gas mode: ; That is: ; In the formula, M 1 is the total instantaneous fuel consumption, M 2 is the total instantaneous gas consumption, M 3 is the total instantaneous ignition oil fuel consumption, L is the LNG consumption in the gas mode, the LNG calorific value is 49539 kJ / kg, D 1 is the ignition oil consumption rate in the gas mode, taking the average value of 11.4 kg / h; In actual operation, introduce the incomplete combustion error coefficient k 燃烧 to correct the emission calculation, that is: ; If the main engine power is below 50% of the rated power, it is in the low-load combustion stage, and the combustion efficiency η 燃烧 further decreases, and k 燃烧 needs to be corrected: ; In the formula, α is the operating condition coefficient, taking 0.3 - 0.5, and η 设计 is the combustion efficiency under the design condition.

[0013] Preferably, in the step S6, by integrating the instantaneous carbon emissions during the construction period, the total carbon emissions of the construction period are obtained, that is, a construction voyage includes dredging q 1 , heavy-load navigation q 2 , mud dumping q 3 , light-load navigation to the dredging area q 4 Four sub-units, count the earthwork volume of each single-voyage construction unit within a month, and obtain the average earthwork volume of the single-voyage construction unit m 土 , and then according to the earthwork volume of a single construction section M 土 , the total number of voyage units is obtained A , M 土 can be determined by geological exploration, engineering design documents or on-site measurement. The calculation formula of the voyage unit A is as follows: ; Calculate the carbon emissions of a single construction section C 燃油单 or C 燃油单 , and the calculation formula is as follows: Fuel mode: ; In the formula, C 燃油 is the carbon emissions per voyage in the fuel mode; Substitute ; into , and calculate the carbon emissions of the ship per day in a single construction section in the fuel mode; Gas mode: ; In the formula, C 燃气 is the carbon emissions per voyage in the gas mode; Substitute ; Substitute , and calculate the carbon emissions of the ship per day in a single construction section in the gas mode.

[0014] Preferably, in step S7, according to historical data, measure the earthwork volume of each construction section of the Yangtze Estuary waterway, count the operation time and earthwork volume of a single ship's voyage of different ships in a single construction section, and according to the average number of construction ships S per day 平均 and the average earthwork volume per ship's voyage m 土 , convert it to 26 days according to the effective working days per month, and calculate the monthly earthwork volume of different ships in a certain construction section M 月 : ; According to the total monthly construction earthwork volume of different ships invested in this section and the measured earthwork volume of the section, calculate the construction period T z : .

[0015] Preferably, in step S8, calculate the carbon emissions of a single ship per ship's voyage per day according to historical data C 燃油 or C 燃气 , and then according to the number of construction ships A per day in the construction section, the daily carbon emissions of a single ship in this section can be calculated C 燃气单 or C 燃气单 , finally, according to the construction period T z , calculate the total carbon emissions of each ship or .

[0016] The beneficial effects of the present invention are as follows: By calculating the shaft power of the dredge pump, the present invention provides key parameter support for the operation of the ship; and provides a method for resistance analysis of the ship and more accurate calculation of the propulsion power. Through the accurate estimation of the form drag, it is possible to better understand the influence of various resistance factors on the ship when it is sailing in water. At the same time, using empirical formulas to calculate the wetted surface area and displacement volume helps to quickly estimate the relevant parameters of the ship in practical applications, providing an important reference basis for ship design and operation; By using methods such as empirical formulas, simulation calculations or actual measurements to calculate the construction period of different construction sections of the waterway, and by calculating the carbon emissions of different sections and different ship types, it can provide a basis for energy conservation and emission reduction, and at the same time can also provide a reference for ship design and operation; Through the method of the present invention, the operation sequence of the ship can be reasonably arranged, the waiting time and empty sailing mileage of the ship can be reduced, the construction efficiency can be improved, and the energy consumption and carbon emissions can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flowchart of a method for calculating the carbon emissions of a trailing suction hopper dredger according to the present invention; Figure 2 is the clear water efficiency curve of the dredge pump of the New Sea Tiger 4 in the embodiment of the present invention; Figure 3 is the flow velocity-clear water efficiency curve of the dredge pump of the New Sea Ox in the embodiment of the present invention; Figure 4 is the flow velocity-clear water efficiency curve of the dredge pump of the New Sea Tiger in the embodiment of the present invention; Figure 5 is the flow velocity-efficiency curve of the clear water test of the dredge pump of the Sea Tiger 8 in the embodiment of the present invention; Figure 6 is the flow velocity-head curve of the high-pressure water pump of the Sea Tiger 8 in the embodiment of the present invention; Figure 7 is the flow velocity-power curve of the high-pressure water pump of the Sea Tiger 8 in the embodiment of the present invention; Figure 8 is the flow velocity-efficiency curve of the high-pressure water pump of the Sea Tiger 8 in the embodiment of the present invention; Figure 9 is the ground speed-rake head resistance power curve of the New Sea Tiger 4 in the D3.0 section in the embodiment of the present invention; Figure 10 is the ground speed-rake head resistance power curve of the New Sea Tiger 4 in the D3.1 section in the embodiment of the present invention; Figure 11 is the ground speed-rake head resistance power curve of the New Sea Tiger 4 in the D3.2 section in the embodiment of the present invention; Figure 12 is the ground speed-rake head resistance power curve of the New Sea Tiger 4 in the D3.3 section in the embodiment of the present invention; Figure 13It is the ground speed - draghead resistance power curve of the D3.4 section of Xin Hai Hu 4 in the embodiment of the present invention; Figure 14 It is the ground speed - draghead resistance power curve of the extended section of Xin Hai Hu 4 in the embodiment of the present invention; Figure 15 It is the schematic diagram of soil classification and correction coefficient values in the embodiment of the present invention. Specific Embodiments

[0018] Next, the technical solution of the present invention will be clearly and completely described in conjunction with the accompanying drawings. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0019] Next, the present invention will be further described in conjunction with the accompanying drawings.

[0020] As Figure 1 shown, a method for calculating the carbon emissions of a trailing suction hopper dredger includes: Step S1, calculating the shaft power of the mud pump.

[0021] In the embodiment, the calculation process of the shaft power of the mud pump is as follows: According to the calculated effective power of the mud pump and the actual pump efficiency, calculate the shaft power of the mud pump, and its calculation formula is as follows: ; In the formula, P 有效 is the effective power of the mud pump, H is the head of the mud pump, Q 1 is the displacement of the mud pump, ρ is the density of the slurry, and g is the acceleration due to gravity; Among them, ; In the formula, V is the flow velocity, and r is the radius of the discharge pipe of the mud pump; ; In the formula, V 2 is the discharge port flow velocity, V 1 is the suction port flow velocity, P 2 is the discharge port pressure, P 1 is the suction pressure, and h is the vertical height distance between the discharge port pressure gauge and the center of the mud pump suction port; The lift of the slurry pump consists of four parts: one is the velocity head, the second is the pressure head, the third is the elevation head, and the fourth is the frictional resistance loss and the elbow resistance loss. Among them, ; In the formula, K 1 and both K 2 are resistance coefficients, which can be queried in the "Code for Design of Dredging and Hydraulic Fill Engineering (JTS 181-5-2012)". L is the straight pipe length of the mud pipe, D is the inner diameter of the straight pipe of the mud pipe, and g is the acceleration of gravity; According to the flow rate-efficiency curve fitting formula, the actual pump efficiency is empirically selected as 0.8 of the theoretical pump efficiency, that is: ; In the formula, η 实际 is the actual pump efficiency of the slurry pump, and η 理论 is the theoretical pump efficiency of the slurry pump, which is obtained through the flow rate-efficiency curve fitting formula in the clean water test, and the flow velocity is the direct acquisition reading of the ship flowmeter.

[0022] The above formula combines multiple parameters and accurately calculates the shaft power of the slurry pump. Among them, the calculation of the lift of the slurry pump considers multiple factors such as the velocity head, pressure head, elevation head, frictional resistance loss and elbow resistance loss, making the calculation result more accurately reflect the actual situation. By dividing the effective power of the slurry pump by the actual pump efficiency, the shaft power of the slurry pump is obtained, providing key parameter support for the operation of the ship.

[0023] Taking Haihu No. 4 as an example: As Figure 2 shown, in the construction report of Haihu No. 4, by screening out the slurry concentration greater than 1.1 t / m³, the following dredging parameters (average values) are obtained The slurry density ρ is 1.24 t / m³, the flow velocity is 7.79 m / s, the inlet pressure P 1 is -0.37 bar, the discharge pressure P 2 is 0.65 bar, and the diameter D of the discharge pipe of the slurry pump is DN900 mm; Elevation head: The vertical height distance between the pressure gauge at the discharge port and the center of the suction port of the slurry pump. For Haihu No. 4, it is about 8 m.

[0024] ; Taking Xin Hainiu or Xin Haihu as an example: As Figure 3 shown, for Xin Hainiu, η 理论 is obtained through the flow velocity-efficiency fitting formula in the clean water test, and the flow velocity is read by the flowmeter: ; As Figure 4 shown, for Xin Haihu, η 理论It is obtained from the flow velocity - efficiency fitting formula in the clear water test, and the flow velocity is read by the flow meter: ; The calculation of the shaft power of the new Hainiu and new Haihu is the same as the calculation steps of Haihu No. 4.

[0025] Taking Haihu No. 8 / 9 as an example: Such as Figure 5 As shown, according to the fine - particle loading model (mixed model), in accordance with the sediment particle size and particle size percentage distribution in the Yangtze River Estuary area, combined with the clear water efficiency and shaft power of the mud pump, the optimal loading flow rate of the double - pump is calculated to be 21000 m³ / h, and the average flow velocity of a single pump is 4.58 m / s. According to the proportional relationship between the mud pump flow rate and the rotational speed Q 1 / Q 2 =n 1 / n 2 , the rotational speed at this time is 160 rpm, and it is obtained from the flow velocity - efficiency fitting formula in the clear water test: ; According to the formula: ; The shaft power of the mud pump is calculated.

[0026] Step S2, calculate the shaft power of the high - pressure flushing water pump.

[0027] In the embodiment, the calculation process of the shaft power of the high - pressure flushing water pump is as follows: Statistical analysis is carried out on the rotational speed, pressure, and power of the high - pressure water pump, and the characteristic curves of the high - pressure water pump at different rotational speeds are plotted. The characteristic curves include the flow velocity - rotational speed - head curve, the flow velocity - rotational speed - power curve, and the flow velocity - rotational speed - efficiency curve, and the formula is obtained by fitting; According to the data of the clear water test of the high - pressure flushing water pump of Haihu No. 8, combined with the specific speed method, the characteristic curves at different rotational speeds are plotted, as shown in Table 1 for example: Table 1

[0028] Determine the flow rate according to the flow velocity of the high - pressure water pump, that is: ; In the formula, V G is the flow velocity of the high - pressure water pump, S G is the discharge pipe diameter area of the high - pressure water pump, r G is the discharge pipe radius of the high - pressure water pump, R G is the discharge pipe diameter of the high - pressure water pump; According to the flow velocity and combined with the flow velocity - rotational speed - head curve, obtain: ; Determine the pump efficiency discount ratio F based on the actual pressure and the theoretical pressure; ; Calculate the theoretical pressure at different rotational speeds, take the ratio with the actual pressure, obtain the pump efficiency discount ratio F at different rotational speeds, and average them to get the pump efficiency discount ratio, that is: ; In the formula, F a is the pump efficiency discount ratio of the a-th group of rotational speeds, and a is the number of rotational speed groups; The total resistance of the pipeline system consists of the following two parts: ; Among them, H G静 is the static head of the elevation difference between the inlet and outlet of the pipeline, and the loss head H G损失 includes the frictional loss along the way and the local resistance loss, and is proportional to the square of the flow rate Q 2 , that is: ; In the formula, k is the pipeline characteristic coefficient, which comprehensively reflects the geometric parameters of the pipeline (length, diameter, roughness) and local resistances (valves, elbows, etc.); Furthermore, establish the pipeline characteristic equation. Assume that H G静 =h, the energy difference generated by the fluid in the pipeline system due to the vertical height difference between the inlet and outlet is ignored, that is: ; The actual operating point of the pump satisfies: ; Subtract the static head h from each group of H 泵i to obtain the corrected head: ; Fit and calculate the pipeline characteristic coefficient k, use the least squares method to fit the data, and obtain the pipeline characteristic coefficient k: ; In the formula, Q 2i is the flow rate of the high-pressure water pump at different rotational speeds, and H 泵i is the head of the high-pressure water pump at different rotational speeds; Calculate the corresponding flow rate according to different pressures and pipeline characteristics, determine the theoretical efficiency by looking up the table according to the corresponding flow velocity, determine the actual pump efficiency according to the theoretical efficiency and the pump efficiency discount ratio, determine the effective power according to the pressure and flow rate, and determine the actual shaft power according to the effective power and the actual pump efficiency, that is: ; That is: ; Wherein, P G实功 is the actual power of the high-pressure water pump, η G实际 is the actual pump efficiency of the high-pressure water pump, and η G理论 is the theoretical pump efficiency of the high-pressure water pump.

[0029] Taking the Xinhaihu 8 as an example: 1) The rotation speed, pressure, and power of the high-pressure water pump of the Xinhaihu 8 are counted as shown in Table 2.

[0030] Table 2

[0031]

[0032] 2) According to the data of the clean water test of the high-pressure water pump of the Haihu No. 8 and combined with the speed ratio method, the characteristic curves at different rotation speeds are drawn: flow velocity - head curve, flow velocity - power curve, flow velocity - efficiency curve, as Figures 6 - 8 shown.

[0033] 3) Determine the flow rate according to the power and rotation speed of the high-pressure water pump; 4) Determine the theoretical pressure according to the flow rate and rotation speed; 5) Determine the pump efficiency discount ratio (average value of multiple groups of data) according to the actual pressure and theoretical pressure; 6) Determine the pipeline characteristics according to the flow rate and actual pressure; 7) Calculate the corresponding flow rate according to different pressures and pipeline characteristics, determine the theoretical efficiency by looking up the table according to the corresponding flow velocity, determine the actual pump efficiency according to the theoretical efficiency and the pump efficiency discount ratio, determine the effective power according to the pressure and flow rate, and determine the actual shaft power according to the effective power and the actual pump efficiency; That is According to the pipeline characteristic curve coefficient obtained in step 6, given the discharge pressure, , , the system head H G is obtained. According to , the flow rate corresponding to the discharge pressure is obtained; Determine the theoretical efficiency according to the corresponding flow rate table and the fitting formula in the flow rate - efficiency curve.

[0034] The pump efficiency discount ratio is averaged according to the theoretical efficiency and the pump discount ratio K to determine the actual pump efficiency: ; Determine the effective power according to the pressure and flow rate: ; Determine the actual shaft power according to the effective power and the actual pump efficiency: .

[0035] Step S3, calculate the main propulsion power of the trailing suction hopper dredger.

[0036] In the embodiment, the calculation process of the main propulsion power of the trailing suction hopper dredger is as follows: According to the principles of physics, in ship propulsion, the propulsion power is used to overcome the resistance suffered by the ship to make the ship move forward. When the ship is sailing at a constant speed, the propulsive force is equal to the resistance suffered by the ship, that is: ; That is: ; In the formula, P C is the main propulsion power of the trailing suction hopper dredger, R is the resistance suffered by the trailing suction hopper dredger, V C is the speed of the trailing suction hopper dredger, R f is the frictional resistance, R w is the wave-making resistance, R s is the form resistance; Among them, The frictional resistance R f is the tangential force generated on the hull surface due to the viscosity of water. It is related to factors such as the wetted surface area of the hull, the kinematic viscosity coefficient of water, the ship speed, and the surface roughness of the hull. The frictional resistance R f is proportional to , that is: ; To simplify the calculation, a frictional resistance coefficient i is set, which is related to the hull roughness, wetted surface area, and Reynolds number. , and the empirical value of the frictional resistance coefficient i for the trailing suction hopper dredger is 0.35 - 0.50; The wave-making resistance R w is the resistance corresponding to the energy consumed by the waves generated when the ship is sailing. Its relationship with the ship speed is relatively complex and is usually related to the square, cube, or even higher powers of the ship speed. For low-speed ships, the wave-making resistance R w accounts for a relatively small proportion of the total resistance. For high-speed ships, the wave-making resistance R w becomes the main resistance component. When the ship speed exceeds the critical value, the wave-making resistance increases sharply, and its growth rate is much faster than that of the frictional resistance, and is proportional to the square or higher powers of the ship speed, that is: ; In the formula, n ≥ 2, and n takes 3; To simplify the calculation, a wave-making resistance coefficient j is set, such that , and the empirical value of the wave-making resistance coefficient j for the trailing suction hopper dredger is 0.03 - 0.06; The form resistance R sIt is mainly the resistance generated by the separation of the water flow at the stern of the ship to form vortices. It is also related to the ship speed and is greatly affected by the hull shape; Form resistance R s One that increases with the increase of the ship speed. Although the proportion it accounts for in the total resistance is usually less than that of the frictional resistance R f and the wave-making resistance R w , it may also have a significant impact on the resistance characteristics of the ship under some special circumstances (such as unreasonable hull shape design).

[0037] Form resistance R s The magnitude of depends on the rationality of the hull shape; by optimizing the hull design and reducing the separation of the water flow at the stern and the formation of vortices, the form resistance R can be reduced s ; in the process of ship design, the influence of form resistance needs to be fully considered, and advanced design concepts and technologies should be adopted to improve the performance and efficiency of the ship; Based on the tide level, tidal current velocity data, and propulsion power table, establish the dredger's excavation and navigation propulsion power under different sections and different times of the deep water channel; When establishing the dredger's excavation and navigation propulsion power under different sections and different times of the deep water channel, the changes in tide level and tidal current velocity data need to be fully considered; the height of the tide level will affect the draft and buoyancy of the ship, thus affecting the demand for propulsion power. The magnitude and direction of the tidal current velocity will also have an impact on the navigation of the ship, increasing or decreasing the consumption of propulsion power; First, according to the obtained tide level and tidal current velocity data, analyze the water flow conditions under different sections and times. Combining the data in the propulsion power table, the propulsion power demand of the dredger under specific conditions can be initially determined. Then, consider the impact of the excavation operation on the propulsion power; during the excavation process, the ship needs to overcome the resistance of the soil and its own weight, which will increase the consumption of propulsion power; by analyzing the characteristics and requirements of the excavation operation, the propulsion power can be further adjusted and optimized; In addition, the influence of other factors on the propulsion power can also be considered, such as wind direction, sea waves, etc. Although these factors are relatively small, they may also have a certain impact on the propulsion power of the ship under certain circumstances. By comprehensively considering various factors, a more accurate and practical dredger excavation and navigation propulsion power model can be established to provide strong support for ship operation and management; In actual calculations, some empirical formulas are often used to estimate the form resistance R s , that is, the ITTC empirical formula is used to calculate the form resistance R s , that is: ; The Holtrop formula is used to calculate the wetted surface area S of the hull C : ; where ρ 1 is the density of water, S C is the wetted surface area of the hull, C DS is the form drag coefficient, B is the beam of the ship, T is the draft, C B is the block coefficient of the ship, L 1 is the length between perpendiculars; The calculation formula for the block coefficient of the ship is as follows: ; where is the displacement volume and Δ is the full load displacement; Furthermore, we get: ; where i is the frictional resistance coefficient and j is the wave-making resistance coefficient; according to the current draft T of the ship and the speed V through water C to calculate the propulsion power, the frictional resistance coefficient i and the wave-making resistance coefficient j will change. Based on a clean hull (roughness ks ≈ 150 μm) and the standard wetted surface area, for a trailing suction hopper dredger, due to fouled bottom and sediment attachment, the roughness may reach ks ≥ 300 μm, and the frictional resistance coefficient needs to be increased, i = 0.35 - 0.50; since the economic speed of a trailing suction hopper dredger is low, the full load design speed is 12 - 14 kn, and the dredging speed is at a low Froude number Fr (Fr < 0.15), the proportion of wave-making resistance decreases and the form drag is dominant, so the wave-making resistance coefficient needs to be decreased, j = 0.03 - 0.06; Finally, we get: .

[0038] The parameters of each ship are shown in Table 3: Table 3

[0039] When establishing the dredging and navigation propulsion power of a trailing suction hopper dredger in different sections and at different times of a deep water channel, it is necessary to fully consider the changes in tide level and tidal current velocity data. The height of the tide level will affect the draft depth and buoyancy of the ship, thus affecting the demand for propulsion power. The magnitude and direction of the tidal current velocity will also have an impact on the navigation of the ship, increasing or decreasing the consumption of propulsion power.

[0040] Based on the obtained tide level and tidal current velocity data, analyze the water flow conditions in different sections and at different times. Combining with the data in the propulsion power table, the propulsion power requirements of the trailing suction hopper dredger under specific conditions can be preliminarily determined. Then, consider the impact of the dredging operation on the propulsion power. During the dredging process, the ship needs to overcome the resistance of the soil and its own weight, which will increase the consumption of propulsion power. By analyzing the characteristics and requirements of the dredging operation, the propulsion power can be further adjusted and optimized.

[0041] In addition, other factors affecting the propulsion power can also be considered, such as wind direction, sea waves, etc. Although these factors are relatively small, they may also have a certain impact on the ship's propulsion power in some cases. By comprehensively considering various factors, a more accurate and practical model for the dredging and navigation propulsion power of the trailing suction hopper dredger can be established, providing strong support for ship operation and management.

[0042] Step S4, calculate the drag power of the dredge head.

[0043] In the embodiment, the calculation process of the drag power of the dredge head is as follows: Obtain the main engine power, auxiliary generator power, and corresponding construction parameters of the ship in different sections and at different times; According to the main engine and auxiliary engine powers, deduct the calculated values of the mud pump, high-pressure flushing water, and propulsion power to obtain the power corresponding to the drag of the dredge head and the dredge arm, and establish a relationship with the dredging speed (speed relative to the ground), that is: ; Calculate to obtain P 耙阻功 , and the corresponding dredging speed V C , draw a curve, and establish the fitting relationship between P 耙阻功 and the ship speed: ; In the formula, P 主瞬 is the instantaneous total power of the ship, that is, the main engine power, P 辅发 is the auxiliary engine power, η is the efficiency of the trailing suction hopper dredger, P 辅助 is the power of the ship's auxiliary equipment, and a, b, and c are all the fitting parameters of P 耙阻功 and the ship speed.

[0044] In actual calculation, first, the main engine power P 主瞬 and the auxiliary generator power P 辅发 need to be accurately measured. These powers can be measured by power measurement equipment installed on the ship or estimated according to the technical parameters and operating status of the engine. Then, calculate the mud pump power P 轴 , the high-pressure flushing water power P G实功 , the propulsion power P C and the power of the auxiliary equipment P 辅助; The calculation of these powers can be carried out according to the methods introduced above. After obtaining each power value, add the main engine power and the auxiliary generator power, and then subtract the total power of the mud pump, high-pressure flushing, propulsion, and auxiliary equipment to obtain the power P corresponding to the drag of the drag head and drag arms. 耙阻功 ; Then, take P 耙阻功 and the corresponding dredging speed V C for data collection. By plotting curves and performing fitting analysis, the relationship between P 耙阻功 and the ship speed can be obtained. This relationship can help us better understand the variation law of the drag head resistance power with the ship speed and provide guidance for optimizing the construction process and improving efficiency.

[0045] Taking the Xin Hai Hu No. 4 as an example, calculate the drag head resistance power (taking the average value) and the corresponding ship's ground speed (average value) in the construction sections D3.0, D3.1, D3.2, D3.3, D3.4 and the extended construction area respectively. Plot the curves of the drag head resistance power and the ground speed, obtain the fitting formula, and establish the relationship between P 耙阻功 and the ship speed in the construction sections as shown in Tables 4, 5 and Figures 9 - 14 as follows: Table 4

[0046] Table 5

[0047] The physical properties of different soil types (such as shear strength, friction coefficient) significantly affect the drag head resistance. It is necessary to consider introducing a soil quality correction coefficient k_soil and incorporate it into the resistance power calculation formula. Obtain the soil type and distribution in the construction area, and combine with the "Dredging Engineering Soil Classification and Resistance Coefficient Manual". The soil classification and correction coefficient values are as Figure 15 shown.

[0048] Multiply the soil quality correction coefficient k 土 directly into the drag resistance power formula, such as in the D3.0 section: ; In the formula and in the figure, x represents V C .

[0049] Among them, the drag head resistance parameters of each ship design are shown in Table 6.

[0050] Table 6

[0051]

[0052] Step S5: According to the power calculation results of steps S1 - S4, form a ship total power calculation model, input the construction status, process parameters, construction section, and construction time, calculate the instantaneous total power of the ship, and then calculate the carbon emissions.

[0053] In the embodiment, the construction state, process parameters, construction section, and construction time are input into the calculation model to calculate the instantaneous total power of the ship, and then the carbon emissions are calculated, that is: The instantaneous total power of the ship P 主瞬 : ; Table 7 Ship main engine load rate - power correspondence table

[0054] Table 8 Ship main engine load rate - fuel consumption rate correspondence table

[0055] As shown in Table 7 and Table 8, Table 7 is the ship main engine load - power table, and Table 8 is the average fuel consumption under different loads of the ship main engine. When the instantaneous total power falls within a certain interval of the ship main engine power, the instantaneous fuel consumption rate of this interval is adopted. The instantaneous emission time is t, then: ; In the formula, M 1 is the fuel consumption, and F is the fuel consumption rate; Table 9

[0056] As shown in Table 9, the instantaneous carbon emissions are calculated according to the carbon dioxide emission coefficient table CFj, which is the carbon emissions of a single ship per single voyage per day: Fuel mode: ; Gas mode: ; That is: ; In the formula, M 1 is the total instantaneous fuel consumption, M 2 is the total instantaneous gas consumption, M 3 is the total instantaneous ignition oil fuel consumption, L is the LNG consumption in the gas mode, the LNG gas calorific value is 49539 kJ / kg, D 1 is the ignition oil consumption rate in the gas mode, taking the average value of 11.4 kg / h; In actual operation, the incomplete combustion error coefficient k is introduced to correct the emission calculation 燃烧 , that is: ; If the main engine power is below 50% of the rated power and in the low - load combustion stage, the combustion efficiency η 燃烧 further decreases, k 燃烧Correction is required: ; where α is the operating condition coefficient, taking 0.3 - 0.5, and η 设计 is the combustion efficiency under the design condition.

[0057] Step S6, integrate the calculation model to calculate the carbon emissions during the construction period.

[0058] In the embodiment, by integrating the instantaneous carbon emissions during the construction period, the total carbon emissions during the construction period can be obtained. This requires determining the time range of the construction period and accumulating the instantaneous carbon emissions at each time point. During the integration process, various factors such as the main engine power, working hours, fuel type, etc. need to be considered to ensure the accuracy of the calculation results; If the main engine uses the fuel mode, then by integrating the instantaneous carbon emissions during the construction period, the total carbon emissions during the construction period are obtained, that is, a construction voyage includes dredging q 1 , heavy-load navigation q 2 , mud dumping q 3 , light-load navigation to the dredging area q 4 Four sub-units, count the earthwork volume of each single-voyage construction unit within a month, and obtain the average earthwork volume of the single-voyage construction unit m 土 , and then according to the earthwork volume of a single construction section M 土 , the total number of voyage units is obtained A , M 土 can be determined by geological exploration, engineering design documents or on-site measurement methods. The calculation formula for the voyage unit A is as follows: ; Calculate the carbon emissions C 燃油单 or C 燃油单 of a single construction section, and the calculation formula is as follows: Fuel mode: ; where C 燃油 is the carbon emissions per voyage in the fuel mode; Substitute ; into , and calculate the carbon emissions of the ship per day in a single construction section in the fuel mode; Gas mode: ; In the formula, C 燃气 is the carbon emission per voyage in the gas mode; Substitute ; into , and calculate the carbon emission of the ship per day in a single construction section in the gas mode.

[0059] According to the main engine bench test data of each ship, determine the fuel consumption under different loads. When the instantaneous total power falls within a certain range of the main engine power, use the instantaneous fuel consumption in this range for calculation. The instantaneous emission time can be determined according to the actual construction situation.

[0060] Finally, through the calculation formula of the total instantaneous fuel consumption, combined with the main engine power, working time and fuel consumption including ignition oil, calculate the total instantaneous fuel consumption. Then, according to the carbon dioxide emission coefficient table, determine the carbon dioxide emission generated by each unit of fuel consumption, and further calculate the instantaneous carbon emission. This calculation process can help us understand the carbon emission situation of the ship under different construction conditions and provide a basis for energy conservation and emission reduction.

[0061] The instantaneous carbon emission of the ship can be calculated based on the total instantaneous fuel consumption and the corresponding emission coefficient. Different fuel types have different emission coefficients, which is due to their different chemical compositions and combustion characteristics. In practical applications, it is necessary to select the appropriate emission coefficient according to the fuel type used by the ship to ensure the accuracy and reliability of the carbon emission calculation.

[0062] Step S7, measure the construction period of different construction sections of the waterway.

[0063] In the embodiment, according to the historical data, measure the earthwork volume of each construction section of the Yangtze Estuary waterway, count the operation time and earthwork volume of a single voyage of different ships in a single construction section, and according to the average number of construction ships per day S 平均 and the average earthwork volume per voyage m 土 , convert it to 26 days according to the effective working days per month, and calculate the monthly earthwork volume of different ships in a certain construction section M 月 : ; According to the total monthly construction earthwork volume of different ships invested in this section and the measured earthwork volume of the section, calculate the construction period T z : ; If the construction vessels are Xinhaihu 4, Haihu 8, Xinhainiu, Xinhaixun, or Haihu, then: 。

[0064] The construction conditions in different construction sections may vary, so the construction period will also differ. To accurately calculate the construction period of different construction sections of the waterway, the following factors need to be considered: The length and soil quality of the construction section: Longer construction sections and complex topographies may increase the construction time; Construction techniques and equipment: Different construction techniques and equipment have different efficiencies, which will affect the construction period; Weather and sea conditions: Severe weather and sea conditions may cause construction interruptions and extend the construction period; By comprehensively considering these factors, methods such as empirical formulas, simulation calculations, or actual measurements can be used to calculate the construction periods of different construction sections of the waterway.

[0065] Step S8, according to the obtained construction periods of different construction sections, calculate the carbon emissions of different construction sections and different ship types.

[0066] In the embodiment, the carbon emissions per day per single vessel for a single voyage are calculated based on historical data C 燃油 or C 燃气 , and then, according to the number of construction vessels A per day in the construction section, the daily carbon emissions of a single vessel in this section can be calculated C 燃油单 or C 燃气单 , and finally, according to the construction period T z , calculate the total carbon emissions of each vessel or 。

[0067] In the embodiment, the average number of construction vessels per day of the same vessel in different construction sections obtained through historical data analysis S 平均 and the average earthwork volume m 土 , based on the number of construction vessels per day, obtain the carbon emissions of the same vessel in different single construction sections C 单 , arrange different vessels for construction according to different construction sections, and based on the total earthwork volume of each construction section and the single-vessel construction volume of different vessels in this section, calculate the number of construction vessels and accumulate to obtain the carbon emissions of the vessels in this section.

[0068] Characteristics of ship types: Parameters such as the main engine power, fuel consumption rate, and navigation speed of different ship types are different, which will affect carbon emissions.

[0069] Environmental conditions of construction sections: The environmental conditions such as water flow velocity, water depth, and soil quality in different construction sections are different, which will affect the operation efficiency and carbon emissions of ships.

[0070] Construction technology and equipment: Different construction technologies and equipment have different energy consumptions, which will affect carbon emissions.

[0071] By calculating the carbon emissions of different sections and different ship types, it can provide a basis for energy conservation and emission reduction, and at the same time can provide a reference for the design and operation of ships.

[0072] There are obvious differences in the environmental conditions such as water flow velocity, water depth, and soil quality in different construction sections of the deep water channel in the Yangtze Estuary. These factors have an important impact on the operation efficiency and carbon emissions of ships. In sections with a relatively fast water flow velocity, such as some areas in the North Passage of the Yangtze Estuary, ships need to consume more energy to overcome the water flow resistance, resulting in an increase in the main propulsion power and a corresponding increase in carbon emissions.

[0073] Water depth is also an important factor affecting carbon emissions. In sections with a relatively shallow water depth, the draft of the ship is relatively large, the friction between the hull and the bottom of the water increases, and the navigation resistance of the ship also increases. This makes both the main propulsion power and the drag power of the drag head increase, resulting in an increase in carbon emissions.

[0074] Soil quality has a significant impact on the drag of the drag head and the power of the slurry pump. In the silty soil area, the drag of the drag head is relatively small, the density of the slurry sucked by the slurry pump is relatively low, and the required power is also relatively small, so the carbon emissions are relatively low. In the sandy soil area, the drag of the drag head is large, and the slurry pump needs to consume more energy to transport the slurry, resulting in an increase in carbon emissions.

[0075] There is a close relationship between the length of the construction period and the total carbon emissions. As the construction period extends, the operation time of the ship increases, and the energy consumption also increases accordingly, resulting in an increase in the total carbon emissions. Through the data analysis of construction projects, the functional relationship between the construction period and the total carbon emissions is established. The extension of the construction period will not only lead to an increase in the total carbon emissions, but also an increase in the carbon emissions per unit volume of soil. This is because during the extension of the construction period, factors such as the aging of the ship's equipment and the increase in maintenance costs will lead to a decrease in the energy utilization efficiency, resulting in an increase in the energy consumption and carbon emissions per unit volume of soil. By optimizing the construction organization and scheduling and shortening the construction period, carbon emissions can be effectively reduced. For example, reasonably arranging the operation sequence of ships, reducing the waiting time and empty sailing mileage of ships, can improve the construction efficiency and reduce the energy consumption and carbon emissions.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating carbon emissions from a trailing suction hopper dredger, characterized in that: include: Step S1, calculating the mud pump shaft power; Step S2, calculating the shaft power of the high-pressure flushing pump; Step S3, calculating the main propulsion power of the trailing suction hopper dredger; Step S4, calculating the drag power of the rake head; Step S5, forming a ship total power calculation model according to the power calculation results of steps S1 to S4, inputting the construction status, process parameters, construction section, and construction time, calculating the instantaneous total power of the ship, and then calculating the carbon emissions; Step S6, integrating the calculation model to calculate the carbon emissions during the construction period; Step S7, calculating the construction period of different construction sections of the waterway; Step S8, according to the calculated construction period of different construction sections, different ships are arranged to carry out construction in different construction sections, and the total comprehensive carbon emissions of the fleet in different construction sections are calculated.

2. The method for calculating carbon emissions of a trailing suction hopper dredger according to claim 1, characterized in that: In step S1, the calculation process of the mud pump shaft power is as follows: According to the calculation of the effective power and actual pump efficiency of the mud pump, the shaft power of the mud pump is calculated. The calculation formula is as follows: ； Where, P 有效 is the effective power of the mud pump, H is the head of the mud pump, Q1 is the displacement of the mud pump, ρ is the density of the mud, and g is the acceleration of gravity; in, ； Where, V is the flow velocity, r is the radius of the mud pump discharge pipe; ； Where, V2 is the discharge velocity, V1 is the suction velocity, P2 is the discharge pressure, P1 is the suction pressure, and h is the vertical height distance between the discharge pressure gauge and the center of the mud pump suction port; The mud pump head consists of four parts: velocity head, pressure head, position head, and resistance loss along the way and elbow resistance loss. ； Where, K1 and K2 are resistance coefficients, L is the length of the mud pipe, D is the inner diameter of the mud pipe, and g is the acceleration of gravity; According to the flow-efficiency curve fitting formula, the actual pump efficiency is empirically selected as 0.8 of the theoretical pump efficiency, that is: ； Where η 实际 is the actual pump efficiency of the mud pump, η 理论 is the theoretical pump efficiency of the mud pump, which is obtained by fitting the flow-efficiency curve in the clean water test. The flow rate is the reading directly collected by the ship flow meter.

3. The method for calculating carbon emissions of a trailing suction hopper dredger according to claim 2, characterized in that: In step S2, the high-pressure flushing pump shaft power calculation process is as follows: Statistics on the speed, pressure and power of the high-pressure water pump are obtained, and the characteristic curves of the high-pressure water pump at different speeds are drawn. The characteristic curves include flow rate-speed-head curve, flow rate-speed-power curve, and flow rate-speed-efficiency curve, and the formula is obtained by fitting; Determine the flow rate according to the high-pressure water pump flow rate, that is: ； Where, V G is the flow rate of the high-pressure water pump, S G is the discharge pipe diameter area of ​​the high-pressure water pump, r G R is the radius of the discharge pipe of the high-pressure water pump, G is the discharge pipe diameter of the high-pressure water pump; According to the flow rate combined with the flow rate-speed-head curve, we get: ； Determine the pump efficiency discount ratio F based on the actual pressure and theoretical pressure; ； According to the theoretical pressure calculated at different speeds, the ratio with the actual pressure is compared to obtain the pump efficiency discount ratio F at different speeds. The pump efficiency discount ratio is obtained by averaging, that is: ； In the formula, F a is the pump efficiency discount ratio of the ath speed group, a is the number of speed groups; According to the flow rate and actual pressure, the pipeline characteristics are determined, namely: The total resistance of the piping system consists of the following two parts: composition: ； Among them, H G静 The static head of the elevation difference between the inlet and outlet of the pipeline, the loss head H G损失 Including friction loss and local resistance loss along the way, it is proportional to the square of the flow rate Q2, that is: ； Where, k is the pipeline characteristic coefficient; Then establish the pipeline characteristic equation, assuming that H G静 =h, the energy difference of the fluid in the pipeline system caused by the vertical height difference between the inlet and outlet, that is: ； The actual working point of the pump meets: ； From each group's H 泵i Subtract the static head h from the above to get the corrected head: ； Fit and calculate the pipeline characteristic coefficient k. Use the least squares method to fit the data and obtain the pipeline characteristic coefficient k: ； Where, Q 2i is the flow rate of the high-pressure water pump at different speeds, H 泵i It is the head of the high-pressure water pump at different speeds; Calculate the corresponding flow rate according to different pressures and pipeline characteristics, determine the theoretical efficiency according to the corresponding flow rate table, determine the actual pump efficiency according to the theoretical efficiency and pump efficiency discount ratio, determine the effective power according to the pressure and flow rate, and determine the actual shaft power according to the effective power and actual pump efficiency, that is: ； Right now: ； Where, P G实功 is the actual power of the high-pressure water pump, η G实际 is the actual pump efficiency of the high-pressure water pump, η G理论 It is the theoretical pump efficiency of high pressure water pump.

4. The method for calculating carbon emissions of a trailing suction hopper dredger according to claim 3, characterized in that: In step S3, the calculation process of the main propulsion power of the trailing suction hopper dredger is as follows: According to the principles of physics, in ship propulsion, propulsion power is used to overcome the resistance of the ship to make the ship move forward. When the ship is sailing at a constant speed, the propulsion force is equal to the resistance of the ship, that is: ； Right now: ； Where, P C is the main propulsion power of the hopper dredger, R is the resistance of the hopper dredger, V C is the speed of the trailing suction hopper dredger, R f is the friction resistance, R w is the wave resistance, R s is the shape drag; in, Friction resistance R f is with is proportional, that is: ； In order to simplify the calculation, the friction resistance coefficient i is set, which is related to the hull roughness, wet surface area and Reynolds number. , the empirical value of the friction resistance coefficient i of the trailing suction dredger is 0.35~0.50; For low-speed ships, the wave-making resistance R w The proportion of total resistance is relatively small. For high-speed ships, the wave-making resistance R w It becomes the main resistance component. When the ship speed exceeds the critical value, the wave resistance increases sharply. Its growth rate is much faster than that of friction resistance and is proportional to the square of the speed or higher power, that is: ； Where, n≥2, n is 3; In order to simplify the calculation, the wave resistance coefficient j is set so that , the empirical value of the wave resistance coefficient j of the trailing suction dredger is 0.03~0.06; The shape resistance R is calculated using the ITTC empirical formula s ,Right now: ； The hull wet surface area S is calculated using the Holtrop formula C : ； Where ρ1 is the density of water, S C is the wet surface area of ​​the hull, C DS is the shape resistance coefficient, B is the ship width, T is the draft, C B is the block coefficient of the ship, L1 is the length of the ship; The calculation formula of the ship's block coefficient is as follows: ； In the formula, is the displacement volume, Δ is the full load displacement; Then we get: ； In the formula, i is the friction resistance coefficient, j is the wave resistance coefficient; Finally, we get: 。 5. The method for calculating carbon emissions of a trailing suction hopper dredger according to claim 4, characterized in that: In step S4, the drag power calculation process of the drag head is as follows: Obtain the ship's main engine power, auxiliary power, and corresponding construction parameters in different sections and at different times; According to the power of the main engine and auxiliary engine, deduct the calculated values ​​of the mud pump, high-pressure water flushing and propulsion power, obtain the power corresponding to the resistance of the rake head and rake arm, and establish a relationship with the dredging speed, that is: ； Calculate P 耙阻功 , and the corresponding dredging speed V C , draw the curve, establish P 耙阻功 Fitting relationship with ship speed: ； Where, P 主瞬 is the instantaneous total power of the ship, P 辅发 is the auxiliary engine power, η is the efficiency of the trailing suction dredger, P 辅助 is the power of ship auxiliary equipment, a, b and c are all P 耙阻功 Fitting parameters related to ship speed.

6. The method for calculating carbon emissions of a trailing suction hopper dredger according to claim 5, characterized in that: In step S5, the construction status, process parameters, construction section, and construction time are input into the calculation model to calculate the instantaneous total power of the ship, and then calculate the carbon emissions, that is: Ship instantaneous total power P 主瞬 : ； Each ship refers to the fuel consumption of the main engine bench test at 50%, 75%, 80% and 100% load. When the instantaneous total power falls within a certain range of the main engine power, the instantaneous fuel consumption rate of the range is adopted. The instantaneous emission time is t, then: ； In the formula, M1 is the fuel consumption, F is the fuel consumption rate; Calculate the instantaneous carbon emissions according to the carbon dioxide emission coefficient table CFj: Fuel Mode: ； Gas Mode: ； Right now: ； Where, M1 is the instantaneous total fuel consumption, M2 is the instantaneous total gas consumption, M3 is the instantaneous total ignition oil fuel consumption, L is the LNG consumption in gas mode, the calorific value of LNG gas is 49539 kJ / kg, D1 is the ignition oil consumption rate in gas mode, the average value is 11.4 kg / h; In actual operation, the incomplete combustion error coefficient is introduced to correct the emission calculation k 燃烧 ,Right now: ； If the main engine power is below 50% of the rated power, it is in the low-load combustion stage, and the combustion efficiency η 燃烧 Further decrease, k 燃烧 Corrections needed: ； In the formula, α is the operating coefficient, which is 0.3-0.5, and η 设计 is the combustion efficiency under design conditions.

7. The method for calculating carbon emissions of a trailing suction hopper dredger according to claim 6, characterized in that: In step S6, the instantaneous carbon emissions are integrated during the construction period to obtain the total carbon emissions during the construction period, that is, a construction ship trip includes dredging. q 1. Heavy-load sailing q 2. Throwing mud q 3. Lightly loaded sailing to the dredging area q 4 Four sub-units, count the earthwork volume of each single ship construction unit within a month, and calculate the average earthwork volume of the single ship construction unit m 土 , and then according to the earthwork volume of a single construction section M 土 , the total ship unit A , M 土 It can be determined through geological exploration, engineering design documents or on-site measurements. A The calculation formula is as follows: ； Calculate the carbon emissions of a single construction section C 燃油单 or C 燃气单 , the calculation formula is as follows: Fuel Mode: ； In the formula, C 燃油 is the carbon emissions per ship trip in fuel oil mode; Will ； Substitution , calculate the carbon emissions of the ship in a single construction section per day under fuel mode; Gas Mode: ； In the formula, C 燃气 is the carbon emissions per ship trip in gas-fired mode; Will ； Substitution , and calculated the carbon emissions of the ship in a single construction section per day under gas mode.

8. The method for calculating carbon emissions of a trailing suction hopper dredger according to claim 7, characterized in that: In step S7, the earthwork volume of each construction section of the Yangtze River Estuary waterway is calculated based on historical data, and the operation time and earthwork volume of each ship in a single construction section are counted. 平均 and the average earthwork volume per ship m 土 , according to the monthly effective working days converted to 26 days, calculate the monthly earthwork volume of different ships in a certain construction section M 月 : ； The construction period is calculated based on the total monthly earthwork volume of different ships in the section and the measured earthwork volume of the section. T z : 。 9. The method for calculating carbon emissions of a trailing suction hopper dredger according to claim 8, characterized in that: In step S8, the carbon emissions per ship per day C are calculated based on historical data. 燃油 or C 燃气 Then, based on the number of construction vessels A per day in the construction section, the daily carbon emissions of a single ship in the section can be calculated. C 燃油单 or C 燃气单 Finally, according to the construction period T z , calculate the total carbon emissions of each ship or .

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