A marine-mounted servo-type exhaust drag reduction chimney

Abstract

This invention provides a marine-mounted, servo-driven exhaust drag-reducing chimney, designed to effectively reduce exhaust back pressure of the ship's main engine and improve energy efficiency. The chimney features an integrated design, structurally connecting the exhaust and intake ducts, with an integrated electric motor and gear transmission mechanism forming its core drive unit. During operation, the system receives and processes environmental data from wind speed and direction sensors in real time. A signal processing unit then issues commands to drive the electric motor, controlling the synchronous rotation of the exhaust and intake ducts to dynamically adjust the direction of the air inlet, ensuring it is always aligned with the incoming airflow. This invention utilizes the Venturi effect to generate auxiliary suction, guiding air to flow in at high speed from the small-diameter intake vent and exit from the large-diameter exhaust vent, creating low pressure at the exhaust outlet and generating suction. This reduces exhaust drag, decreases engine fuel consumption, and improves the ship's operational efficiency.

Description

Technical Field

[0001] This invention relates to the field of ship chimney technology, and in particular to a ship-mounted follow-up type chimney with reduced exhaust resistance. Background Technology

[0002] Conventional ship exhaust chimneys are of the standard bent pipe type. However, due to increasingly stringent standards for ship engine exhaust control, some ship engine exhaust systems require the installation of SCR (Selective Catalytic Reduction) systems, exhaust gas boilers or economizers, silencers, and desulfurization systems to treat the exhaust process. This can lead to the following problems:

[0003] 1. With the increase of equipment in the exhaust system of ship engines, the exhaust resistance increases, exceeding the recommended exhaust pressure value, resulting in an increase in fuel consumption rate.

[0004] 2. When calculating the exhaust back pressure of marine engines, only the operating condition under 85% load is considered. When operating at a load of more than 85%, the exhaust back pressure may exceed the recommended value, resulting in increased fuel consumption rate when operating at higher loads.

[0005] In view of the shortcomings of existing exhaust chimneys, the present invention provides a marine follow-up type exhaust resistance reducing chimney to overcome the exhaust resistance of conventional marine exhaust chimneys and reduce fuel consumption. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a marine follow-up type exhaust resistance reduction chimney, including an exhaust pipe and an air inlet pipe. The exhaust pipe includes a vertical section and a bend section connected together. The lower end of the vertical section is sleeved on the outer wall of the main engine exhaust pipe. The bend section is a quarter circle arc. The exhaust port of the bend section faces the horizontal direction. The wall of the bend section is connected to the air inlet pipe. The opening direction of the air inlet of the air inlet pipe is opposite to the opening direction of the exhaust port. The horizontal line passing through the center of the exhaust port coincides with the central axis of the air inlet pipe. The inner diameter of the air inlet pipe is smaller than the inner diameter of the exhaust pipe.

[0007] The outer side of the main exhaust pipe is surrounded by a chimney top cover. The sleeve is coaxially arranged with the main exhaust pipe and fixedly connected to the chimney top cover. The lower end of the vertical section of the exhaust pipe is sleeved in the inner opening of the rotating sleeve. The outer wall of the rotating sleeve is fixedly connected to the sleeve so that the exhaust pipe can rotate around the main exhaust pipe.

[0008] Optionally, a follower gear is also coaxially fixed to the outer wall of the vertical section of the exhaust pipe. The follower gear is located above the pulley and meshes with the drive gear, which is driven by an electric motor.

[0009] Optionally, it also includes a wind speed and direction sensor and a signal processing unit. The wind speed and direction sensor is used to collect wind direction data in real time. After receiving the wind direction signal from the wind speed and direction sensor, the signal processing unit controls the electric motor to run until the air intake duct is adjusted to be parallel to the current wind direction.

[0010] Optionally, the air inlet of the air inlet duct adopts a flared design.

[0011] Optionally, the expansion angle β of the air inlet flare can be 10°~15°.

[0012] Optionally, the main unit exhaust flow rate ,in For the host power, For fuel consumption rate, For fuel density, The excess air coefficient, The gas constant is... The exhaust temperature, Atmospheric pressure For air quality.

[0013] Optionally, the inlet air velocity greater than the exhaust port velocity , =1.2~1.5 .

[0014] Optionally, the main unit power is increased by n times, and the diameter of the air inlet and exhaust port is increased. times.

[0015] As described above, this invention provides a marine-mounted, servo-driven exhaust drag-reducing chimney, designed to effectively reduce exhaust back pressure of the ship's main engine and improve energy efficiency. The chimney features an integrated design, structurally connecting the exhaust pipe and air intake pipe, with an integrated electric motor and gear transmission mechanism forming its core drive unit. During operation, the system receives and processes environmental data from wind speed and direction sensors in real time. The signal processing unit then issues commands to drive the electric motor, thereby controlling the synchronous rotation of the exhaust pipe and air intake pipe, dynamically adjusting the direction of the air intake to ensure it is always aligned with the incoming airflow. This invention cleverly utilizes the Venturi effect to generate auxiliary suction, guiding air to flow in at high speed from the small-diameter air intake flare and exit from the large-diameter exhaust port, creating low pressure at the exhaust pipe outlet and generating suction, thereby reducing exhaust resistance, decreasing engine fuel consumption, and improving the ship's navigation economic efficiency. Attached Figure Description

[0016] Figure 1 The diagram shown is an overall schematic of the chimney structure in this invention.

[0017] Figure 2 The diagram shown is a partially enlarged schematic of the chimney structure in this invention.

[0018] Figure 3 The diagram shown is a schematic diagram of the logic control for the rotation of the exhaust pipe in this invention.

[0019] Component designation explanation

[0020] Chimney top cover 100, main exhaust pipe 11, exhaust pipe 12, air inlet pipe 13, sleeve pipe 14, follower gear 15, drive gear 16, rotating sleeve 17, electric motor 18. Detailed Implementation

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0022] In the detailed description of embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0023] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for the device in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or there may be one or more layers in between. The phrase “between” as used herein includes both endpoint values.

[0024] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are formed in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0025] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0026] like Figures 1 to 3 As shown, the present invention provides a marine servo-type exhaust resistance reducing chimney, including an exhaust pipe 12 and an air inlet pipe 13;

[0027] The exhaust pipe 12 includes a vertical section and a bend section connected together. The lower end of the vertical section is fitted onto the outer wall of the main exhaust pipe 11. The bend section is a quarter-circle arc. The exhaust port of the bend section faces the horizontal direction. The pipe wall of the bend section is connected to an air inlet pipe. The opening direction of the air inlet of the air inlet pipe 13 is opposite to the opening direction of the exhaust port. The horizontal line passing through the center of the exhaust port coincides with the central axis of the air inlet pipe. The inner diameter of the air inlet pipe 13 is smaller than the inner diameter of the exhaust pipe 12. The inner diameter of the exhaust pipe 12 is slightly larger than the outer diameter of the main exhaust pipe 11 to facilitate assembly.

[0028] The outer side of the main exhaust pipe 11 is surrounded by a chimney top cover 100. The sleeve pipe 14 is coaxially arranged with the main exhaust pipe 11 and fixedly connected to the chimney top cover 100. The lower end of the vertical section of the exhaust pipe 12 is sleeved in the inner opening of the rotating sleeve 17. The outer wall of the rotating sleeve 17 is fixedly connected to the sleeve pipe 14 so that the exhaust pipe 12 can rotate around the main exhaust pipe 11.

[0029] Furthermore, a follower gear 15 is coaxially fixed to the outer wall of the vertical section of the exhaust pipe 12. The follower gear 15 is located above the pulley and meshes with the drive gear 16, which is driven by an electric motor 18.

[0030] Furthermore, it also includes a wind speed and direction sensor and a signal processing unit. The wind speed and direction sensor is used to collect wind direction data in real time. After receiving the wind direction signal from the wind speed and direction sensor, the signal processing unit controls the electric motor to run until the air intake duct is adjusted to be parallel to the current wind direction.

[0031] The materials and wall thickness of exhaust pipes, air intake pipes, and bushings must meet the corrosion resistance and vibration resistance requirements of ship navigation conditions and marine environment, such as stainless steel, nickel-based alloys, or steel with appropriate anti-corrosion treatment. The wall thickness should be calculated and optimized according to the actual working conditions to ensure that the overall durability and safety requirements in the marine environment are met.

[0032] Furthermore, the air inlet of the air inlet duct 13 adopts a flared (gradually expanding) design, which aims to optimize air intake performance and system efficiency. Through streamlined transition, it effectively reduces local resistance and turbulence when air flows in, improves air intake uniformity and stability, and reduces noise and energy loss.

[0033] The operating logic and theoretical calculations of the entire chimney system are as follows:

[0034] (I) System Operation Logic: The device receives signals from the anemometer and wind direction sensor. These signals are then sent to the processing unit, which uses an electric motor to control the adjustment of the air inlet direction. Simultaneously, the actual turning angle of the air inlet is fed back to the processing unit in real time. The unit compares this angle with the target angle and corrects the command to ensure precise turning. The specific system operation logic is as follows:

[0035] The entire system operates in a logical hierarchy of “signal acquisition → processing → driving → execution”, with each link transmitting signals or power in one direction and having one feedback loop.

[0036] (1) Signal acquisition end: The wind speed and direction sensor is the signal source of the whole system and is responsible for capturing the external wind speed and direction parameters in real time.

[0037] (2) Signal processing unit: The sensor sends the raw data to the processing unit; the core function of the processing unit is to filter (remove interference), amplify (enhance weak signals) and make logical judgments (calculate the angle that the air inlet should be adjusted).

[0038] (3) Processing unit to drive element: The processing unit sends start, forward and reverse rotation, stop and other commands to the electric motor according to the calculation results; the electric motor is the power source of the system and outputs rotational power after receiving the command.

[0039] (4) Drive element to transmission mechanism: The gear transmission mechanism includes the driving gear and the follower gear. Their function is to reduce speed (reduce motor speed) and amplify torque (increase driving force), and to transmit the motor power to the actuator after optimization.

[0040] (5) Execution end: The air inlet steering mechanism receives the optimized power and finally completes the steering action of the air inlet to achieve angle adjustment.

[0041] (6) Feedback loop (closed-loop control): The air inlet turning mechanism is connected to the information processing unit. This loop allows the processing unit to obtain the actual turning angle of the air inlet in real time, compare it with the target angle and correct the command to ensure accurate turning.

[0042] (II) Theoretical Calculation

[0043] This invention utilizes the Venturi effect, and its core lies in the combination of Bernoulli's equation and the continuity equation. For incompressible fluids (ship exhaust can be approximated as incompressible), the continuity equation is: ( Volumetric flow rate, For the flow area, (where the velocity is 0); Bernoulli's equation is: ( For pressure, For fluid density, (At its height). Small-diameter air inlet ( Small) to reduce flow rate Increase, according to Bernoulli's equation, the pressure downstream of the air inlet (exhaust outlet) increases. This reduces the resistance of the exhaust pipe, creating a "suction effect".

[0044] (1) The exhaust flow of a ship's main engine has the characteristic of dynamic change with the load. The follow-up air inlet of the present invention can match the wind direction in real time to ensure that the air intake direction is consistent with the wind field of the ship's navigation and maximize the use of the "ejection effect" of the ambient wind; the Venturi structure, through the "contraction and expansion" flow channel, increases the local flow velocity while avoiding exhaust backflow, which is fundamentally different from the "resistance accumulation" of conventional bent pipe chimneys.

[0045] (2) Calculation of key dimensions: Optimization matching of air inlet, exhaust outlet and main unit power

[0046] a. Main unit exhaust flow rate With host power Fuel consumption rate Fuel density Exhaust coefficient (The excess air coefficient, typically 1.6~2.2 for the main unit, is related, and the formula derivation is as follows:)

[0047]

[0048] Rated power of the host ( );

[0049] Fuel consumption rate ( Typical values ​​for diesel engines (0.2~0.25);

[0050] Fuel density ( (e.g., heavy diesel oil, approximately 850-950).

[0051] Excess air coefficient;

[0052] Gas constant (air) =287 );

[0053] Exhaust temperature (K, typical value for diesel engine exhaust is 400~600K).

[0054] Atmospheric pressure (Pa, taken as 101325);

[0055] Air mass (kg, here referring to air mass per unit time).

[0056] The rated exhaust flow rate under the rated power of the main unit can be calculated using this formula. This serves as the basis for the design of the dimensions of the air inlet and exhaust outlet.

[0057] b. Calculation of the dimensions of the air inlet flare and the exhaust outlet

[0058] The key to the Venturi structure is the area ratio of the inlet (small diameter) to the outlet (large diameter), which needs to satisfy the goals of flow continuity and resistance reduction. Let the cross-sectional area of ​​the inlet duct 13 be... The area of ​​exhaust pipe 12 is ,but:

[0059] Flow velocity matching: To ensure effective suction from the Venturi effect, the inlet flow velocity should be... It needs to be greater than the exhaust port velocity. Combined with traffic , can be obtained In engineering, it is usually taken =1.2~1.5 This is to ensure that the pressure drop is large enough.

[0060] Relationship with main unit power: The higher the main unit power, the greater the exhaust flow. The larger the diameter, the larger the inner diameter of the air inlet duct 13. and the inner diameter of exhaust pipe 12 Need to follow The square root relationship increases (or the square root relationship based on flow rate increases). Taking a certain type of diesel engine as an example, if the main engine power increases from... kW increased to 2x With a power output of approximately kW and an exhaust flow rate nearly doubling, the diameters of the air inlet and exhaust outlet need to be increased by approximately [amount missing]. ≈1.414 times. That is, if the main unit power increases by n times, the diameter of the air inlet and exhaust outlet needs to be increased. times.

[0061] Optimization of the inlet flare: The expansion angle β of the inlet flare (typically 10°~15°) needs to be verified through fluid simulation to ensure that there is no air separation within the flare and that pressure loss is minimized. A three-dimensional model is established to simulate the velocity and pressure fields under different expansion angles, and finally, the structural parameters that maximize the "inlet pressure loss + Venturi suction gain" are selected. The specific method is as follows:

[0062] Simulation verification was performed using commonly used engineering software such as UG, ANSYS ICEM, and ANSYS Fluent. The process involved geometric modeling, mesh generation, and simulation settings, ultimately selecting the optimal parameters. The detailed steps are as follows:

[0063] ① Parametric 3D modeling (UG software can be used):

[0064] First, simplify the chimney's bell-shaped structure, ignoring irrelevant details such as chamfers and small protrusions, retaining only the core structures of the inlet section, the bell-shaped expansion section, and the outlet end. Using the inlet inner diameter, outlet inner diameter, and axial length as fixed parameters, establish 3D models of the fluid domain with different expansion angles (e.g., 5°, 10°, 15°, etc.), ensuring that the geometric features of each model differ only in the expansion angle, facilitating subsequent comparative analysis. After modeling, check whether the model is closed to avoid holes affecting the simulation.

[0065] ② Mesh generation (ANSYS ICEM software can be used):

[0066] Import the 3D models of each expansion angle into the software and divide the area into three regions: the inlet surface, the outlet surface, and the avoidance surface. Select tetrahedral mesh type and set the mesh cell size to 0.02m. Set 25 boundary layers near the avoidance surface at the horn opening, with a boundary layer growth rate of 1.2 and a first layer height of 0.111115m. After completing the meshing, verify mesh independence by gradually refining the mesh. If the fluctuation of core data such as pressure loss is not less than 3%, the current mesh parameters are considered valid.

[0067] ③ Simulation preprocessing (ANSYS Fluent software can be used):

[0068] Import the pre-defined mesh, first select the SST turbulence model, which offers high accuracy in simulating separated flows and meets the requirements for verifying the flared airflow at the chimney; then set the roughness avoidance to match the surface characteristics of the actual chimney material. For boundary conditions, input the actual velocity or volumetric flow rate of the marine exhaust gas at the inlet surface, and set the outlet surface to atmospheric back pressure to match the external environment during ship navigation.

[0069] ④ Numerical simulation calculation:

[0070] Set the solver to a three-dimensional steady viscous solution, using total pressure and static pressure as acceptance criteria, and submit the calculation. Monitor the calculation curves in real time during the process. Acceptance is indicated when the curves are stable and without fluctuations. If divergence occurs, the mesh quality or boundary condition settings need to be checked again, corrected, and the calculation resubmitted. This process is repeated to complete the simulation of all models with different expansion angles.

[0071] ⑤ Flow field results analysis:

[0072] After the simulation is completed, examine the velocity and pressure field data for each model. Determine if there is airflow separation within the bell mouth using the velocity vector diagram, and calculate the inlet pressure drop using the pressure contour map. Extract relevant data on the suction gain by applying the Venturi effect principle. Record the airflow separation, inlet pressure drop, and suction gain values ​​for each expansion angle model.

[0073] ⑥ Selecting the optimal structural parameters:

[0074] Comparing all model data, models with airflow separation were prioritized for elimination. Among the models without separation, the model with the smallest inlet pressure loss and the largest Venturi suction gain was selected, and its corresponding expansion angle is the optimal structural parameter for the bell mouth.

[0075] The servo-type exhaust resistance reduction chimney of this invention utilizes the Venturi effect to generate suction force on the exhaust gas of the chimney by the wind flow during navigation. It can also adjust the direction of the air inlet at any time by receiving the wind speed and direction instrument signal and using an electric motor control device. When the exhaust pipe of the ship's main engine is equipped with a lot of exhaust gas treatment devices or is operating at more than 85% load, resulting in increased exhaust resistance, it can effectively reduce the exhaust resistance of the ship's main engine and reduce fuel consumption.

[0076] The rate of decrease in drag can be obtained through the following calculation process:

[0077] Total resistance of the ship's exhaust system It consists of frictional resistance and local resistance, and the formula is:

[0078]

[0079] Friction coefficient (related to Reynolds number) (related to pipe wall roughness)

[0080] :Exhaust pipe length;

[0081] : Inner diameter of the exhaust pipe;

[0082] Local resistance coefficient (such as the local loss coefficient of elbows, valves, and venturi structures).

[0083] This invention utilizes the "suction effect" of the Venturi structure to reduce the local drag coefficient. The resistance is reduced (because the low pressure at the outlet partially offsets the friction loss). Let the resistance of a conventional chimney be... The resistance of the present invention is The rate of decrease in resistance is:

[0084]

[0085] Reduced exhaust resistance directly reduces the exhaust back pressure of the main engine, thereby reducing fuel consumption. Based on the characteristics of diesel engines, for every 1 kPa reduction in exhaust back pressure, fuel consumption can be reduced by 0.5% to 1% (the specific reduction needs to be determined in conjunction with the main engine bench test calibration). Combined with the annual operating time of the main engine and fuel prices, the annual fuel cost savings can be calculated, further highlighting the economic advantages of this invention.

[0086] In summary, this invention provides a marine-mounted, servo-driven exhaust drag-reducing chimney, designed to effectively reduce exhaust back pressure of the ship's main engine and improve energy efficiency. The chimney features an integrated design, structurally connecting the exhaust and intake ducts, with an integrated electric motor and gear transmission mechanism forming its core drive unit. During operation, the system receives and processes environmental data from wind speed and direction sensors in real time. The signal processing unit then issues commands to drive the electric motor, controlling the synchronous rotation of the exhaust and intake ducts to dynamically adjust the direction of the air inlet, ensuring it is always aligned with the incoming airflow. This invention cleverly utilizes the Venturi effect to generate auxiliary suction, guiding air to flow in at high speed from the small-diameter intake vent and exit from the large-diameter exhaust outlet, creating low pressure at the exhaust pipe outlet and generating suction. This reduces exhaust resistance, decreases engine fuel consumption, and improves the ship's operational efficiency.

[0087] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A marine-mounted, follow-up type chimney with reduced exhaust resistance, characterized in that, It includes an exhaust pipe and an air inlet pipe. The exhaust pipe includes a connected vertical section and a bend section. The lower end of the vertical section is fitted onto the outer wall of the main unit's exhaust pipe. The bend section is a quarter-circle arc. The exhaust port of the bend section faces horizontally. The wall of the bend section is connected to an air inlet pipe. The opening direction of the air inlet of the air inlet pipe is opposite to the opening direction of the exhaust port. The horizontal line passing through the center of the exhaust port coincides with the central axis of the air inlet pipe. The inner diameter of the air inlet pipe is smaller than the inner diameter of the exhaust pipe. The outer side of the main exhaust pipe is surrounded by a chimney top cover. The sleeve is coaxially arranged with the main exhaust pipe and fixedly connected to the chimney top cover. The lower end of the vertical section of the exhaust pipe is sleeved in the inner opening of the rotating sleeve. The outer wall of the rotating sleeve is fixedly connected to the sleeve so that the exhaust pipe can rotate around the main exhaust pipe.

2. The marine-mounted, servo-driven, low-exhaust-resistance chimney according to claim 1, characterized in that: The outer wall of the vertical section of the exhaust pipe is also coaxially fixed with a follower gear, which is located above the pulley. The follower gear meshes with the drive gear, which is driven by an electric motor.

3. The marine-mounted, servo-driven, low-exhaust-resistance chimney according to claim 2, characterized in that: It also includes a wind speed and direction sensor and a signal processing unit. The wind speed and direction sensor is used to collect wind direction data in real time. After receiving the wind direction signal from the wind speed and direction sensor, the signal processing unit controls the electric motor to run until the air intake duct is adjusted to be parallel to the current wind direction.

4. The marine-mounted, servo-driven, low-exhaust-resistance chimney according to claim 1, characterized in that: The air inlet of the air inlet duct adopts a flared design.

5. The marine-mounted, servo-driven, low-exhaust-resistance chimney according to claim 4, characterized in that: The expansion angle β of the air inlet flare is 10°~15°.

6. The marine-mounted, servo-driven, low-exhaust-resistance chimney according to claim 1, characterized in that: Main unit exhaust flow ,in For the host power, For fuel consumption rate, For fuel density, The excess air coefficient, The gas constant is... The exhaust temperature, Atmospheric pressure For air quality.

7. The marine-mounted, servo-driven, low-exhaust-resistance chimney according to claim 1, characterized in that: Inlet air velocity greater than the exhaust port velocity , =1.2~1.5 .

8. The marine-mounted, servo-driven, low-exhaust-resistance chimney according to claim 1, characterized in that: The main unit power is increased by n times, and the diameter of the air inlet and exhaust port is increased. times.

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