A sewage pipe diffuser for port sewage dilution and diffusion discharge

Abstract

This invention relates to a sewage pipe diffuser for diluting and discharging port sewage, belonging to the field of port sewage treatment technology. It includes: a delivery pipe, risers, a backpressure check valve, and an anti-backflow structure. The delivery pipe comprises a main pipe and a tail pipe. The main pipe axis is horizontal, and the bottom end of the tail pipe is connected to the output end of the main pipe. The top end of the tail pipe is detachably connected to an anti-backflow structure for sealing the top of the tail pipe. Multiple risers are welded to the outer wall of the main pipe at equal intervals along the main pipe axis. The top end of each riser is detachably connected to a backpressure check valve, and the bottom end of the riser is connected to the main pipe. When sewage pumping stops or the pressure inside the main pipe is lower than the external seawater static and dynamic pressure, the backpressure check valve automatically closes, preventing seawater carrying seabed sediments from flowing back into the sewage discharge diffuser. Furthermore, the backpressure valve itself plays a role in rectifying the sewage discharge and forming a stable jet, which helps improve the sewage diffusion effect.

Description

Technical Field

[0001] This invention relates to the field of port sewage treatment technology, and in particular to a sewage pipe diffuser for diluting and discharging port sewage. Background Technology

[0002] Wastewater discharge projects typically involve pressurizing treated effluent through pumping stations, then discharging it via offshore diversion pipes and seabed diffusers into a high-convective-current area at a certain distance and depth offshore. The tidal forces dilute, diffuse, degrade, and self-purify the effluent, achieving the final disposal purpose and reducing its impact on the port area environment. After being discharged from the outlet, the wastewater rapidly mixes with the surrounding water under its own momentum and the dynamic forces of the marine environment, thus becoming highly diluted.

[0003] In existing technologies, a typical wastewater discharge diffuser usually consists of a main delivery pipeline laid on the seabed and multiple vertical or inclined risers installed at certain intervals along it. During system operation, pressurized wastewater is pumped from an onshore pumping station through the main pipeline and then sprayed upwards into the water body through the risers, utilizing the dynamics of the surrounding water for dilution and diffusion. In environments with frequently changing tidal directions, if the system pumps stop or the pressure in the main delivery pipeline fluctuates, seawater carrying seabed sediments can easily backflow into the wastewater discharge diffuser, causing blockage. Summary of the Invention

[0004] To address the shortcomings of related technologies, this invention provides a sewage pipe diffuser for diluting and discharging port sewage. A back pressure check valve is installed at the output end of the diffuser to solve the technical problem that seawater can easily carry seabed sediments back into the sewage discharge diffuser.

[0005] This invention provides a sewage pipe diffuser for diluting and discharging port sewage, comprising: a conveying pipe, a riser, a back pressure check valve, and an anti-backflow structure; the conveying pipe includes a main pipe and a tail pipe; the main pipe axis is horizontal and straight, the bottom end of the tail pipe is connected to the output end of the main pipe, and the top end of the tail pipe is detachably connected to the anti-backflow structure for sealing the top end of the tail pipe; multiple risers are welded to the outer wall of the main pipe and arranged at equal intervals along the main pipe axis; the top end of the riser is detachably connected to the back pressure check valve, and the bottom end of the riser is connected to the main pipe.

[0006] In some embodiments, the sewage pipe diffuser for diluting and discharging port sewage also includes a wireless water quality monitor for detecting the concentration of pollutants in seawater; a sampling probe is mounted above each back pressure check valve and positioned directly above the valve port of the back pressure check valve.

[0007] In some embodiments, the delivery pipe and riser are buried in silty clay in a deep trench area near the shoreline; the back pressure check valve and anti-backflow structure are close to and higher than the bottom surface of the deep trench area; the depth of the deep trench area is greater than or equal to 10m; the spacing s between adjacent risers satisfies the following formula:

[0008] Where s is the distance between adjacent risers in meters; K is a given coefficient; The design flow rate for a single riser is expressed in units of... v is the average flow velocity of seawater in the deep channel, in m / s; d is the inner diameter of the riser, in m.

[0009] In some embodiments, when the area where the sewage pipe diffuser for diluting and discharging port sewage is installed has the characteristics of an open nearshore sea area with seawater flow driven mainly by tides and a monsoon climate zone, the value of K ranges from 0.22 to 0.28.

[0010] In some embodiments, the delivery pipe is a tapered pipe, and the top of the tail pipe is the small-diameter end of the delivery pipe.

[0011] In some embodiments, the tailpipe includes a bridging section and a guide section; the main pipe axis, the bridging section axis and the guide section axis are smoothly connected in sequence, the guide section axis is a straight line and the bridging section axis is an arc.

[0012] In some embodiments, the angle between the guide segment axis and the horizontal plane is 30° to 65°.

[0013] In some embodiments, the back pressure check valve is a duckbill valve; the length direction of the duckbill valve orifice is perpendicular to the axis of the main pipe.

[0014] In some embodiments, the riser includes a straight pipe section and a tapered pipe section. The two ends of the straight pipe section are connected to the main pipe and the large-diameter end of the tapered pipe section, respectively, and the small-diameter end of the tapered pipe section is connected to a back pressure check valve.

[0015] In some embodiments, the delivery pipe and riser are one of Q235B steel pipe, welded steel pipe, or fiberglass reinforced plastic pipe; the anti-backflow unit is a flange cover or valve.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention automatically closes the back-pressure check valve when sewage pumping stops or the pressure inside the main pipe is lower than the external seawater static and dynamic pressure, preventing seawater carrying seabed sediments from flowing back into the sewage discharge diffuser. The detachable design of the back-pressure check valve facilitates its replacement or cleaning, significantly reducing the long-term operation and maintenance costs and downtime of the sewage pipe diffuser used for dilution and diffusion discharge in ports. Furthermore, the back-pressure valve itself plays a role in rectifying the sewage discharge and forming a stable jet, contributing to improved sewage diffusion effects.

[0017] 2. This invention involves installing a wireless water quality monitoring instrument at a fixed distance directly above the valve port of each back-pressure check valve. The probe of this instrument faces directly towards the initial mixing zone of the sewage plume. This arrangement allows for real-time and continuous capture of the initial mixing effect of the sewage discharged from the riser with seawater, i.e., near-field dilution, as well as changes in the concentrations of key pollutants such as chemical oxygen demand (COD), ammonia nitrogen, and suspended solids. The wireless transmission method eliminates the need for complex submarine cable laying, improving reliability and deployment flexibility.

[0018] 3. This invention, using hydrological data from a preset total discharge flow rate, a selected pipe diameter, and the expected installation location, can calculate the theoretically optimal riser spacing using a formula to balance the following objectives: 1) Avoiding premature plume merging. 2) Ensuring continuous coverage area. 3) The spacing design dynamically adapts to the specific hydrodynamic conditions of the installation point, ensuring that the sewage jet can fully utilize environmental currents for diffusion, rather than conflicting with them. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 A schematic diagram of one implementation method for a sewage pipe diffuser used for diluting and dispersing port sewage; Figure 2 Schematic diagram of another implementation of a sewage pipe diffuser for diluting and dispersing port sewage; Figure 3 A schematic diagram showing the connection between a sewage pipe diffuser and a sewage treatment plant for diluting and dispersing port wastewater. Figure 4 Horizontal pollutant concentration diffusion diagram for sewage pipe diffusers used in port wastewater dilution and diffusion discharge; Figure 5 Vertical pollutant concentration diffusion diagram of a sewage pipe diffuser used for diluting and dispersing port sewage.

[0020] In the diagram: 1. Delivery pipe; 11. Main pipe; 12. Tail pipe; 121. Bridging section; 122. Guide section; 2. Riser; 21. Straight pipe section; 22. Conical pipe section; 4. Back pressure check valve; 5. Anti-backflow structure; 6. Wireless water quality monitor; 7. Sewage treatment plant; 8. Drainage pipe; 9. Pumping station. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the terms "center", "lateral", "longitudinal", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] like Figure 1-3 As shown, in an illustrative embodiment of a sewage pipe diffuser for diluting and discharging port sewage according to the present invention, the sewage pipe diffuser for diluting and discharging port sewage includes: This invention provides a sewage pipe diffuser for diluting and discharging port sewage, comprising: a conveying pipe 1, a riser 2, a backpressure check valve 4, and an anti-backflow structure 5; the conveying pipe 1 includes a main pipe 11 and a tail pipe 12; the axis of the main pipe 11 is a horizontal straight line, the bottom end of the tail pipe 12 is connected to the output end of the main pipe 11, and the top end of the tail pipe 12 is detachably connected to the anti-backflow structure 5 for sealing the top end of the tail pipe 12; multiple risers 2 are welded to the outer wall of the main pipe 11 at equal intervals along the axial direction of the main pipe 11; the top end of the riser 2 is detachably connected to the backpressure check valve 4, and the bottom end of the riser 2 is connected to the main pipe 11. A sewage treatment plant 7 transports sewage to a pumping station 9 through a diversion pipe 8, and the pumping station 9 pumps sewage to the main pipe 11 through another diversion pipe 8.

[0026] Tailpipe 12 serves as an extension output end of main pipe 11, with its top sealed by a detachable anti-backflow structure 5, forming a closed end. During system operation, wastewater flows within main pipe 11 and is evenly distributed into each riser 2, after which residual water is pushed into tailpipe 12. Because tailpipe 12 is closed at its end, it creates a certain back pressure, which helps to balance the pressure distribution within the entire conveying pipe 1, especially in the section near the tail end. This avoids the problems of insufficient wastewater flow and poor dilution effect caused by traditional open tail ends or improper design. Simultaneously, the detachable anti-backflow structure 5 facilitates regular flushing and cleaning of the conveying pipe 1, removing sludge and preventing blockage.

[0027] The welding of the main pipe 11 and riser 2 ensures the robustness and sealing of the connection between riser 2 and main pipe 11, and can withstand the stress and corrosion brought about by the complex seabed environment. The equidistant arrangement of risers 2 is an optimized layout based on hydraulic calculations and environmental models. Its purpose is to ensure that the sewage jets exiting from different risers 2 have consistent or similar initial dilution and diffusion trajectories under the same environmental dynamic conditions (such as tidal currents). Compared with the potential for insufficient local dilution or insufficient sewage coverage due to non-equidistant arrangement, the equidistant arrangement of risers 2 is a key design for achieving rapid and uniform diffusion of pollutants in the target sea area.

[0028] The back-pressure check valve 4 opens when the sewage pressure pumped to the delivery pipe 1 is high, allowing sewage to spray upwards into the water body. When sewage pumping stops or the pressure inside the main pipe 11 is lower than the external seawater static and dynamic pressure, the back-pressure check valve 4 automatically closes, preventing seawater carrying seabed sediments from flowing back into the sewage discharge diffuser. The detachable design of the back-pressure check valve 4 facilitates its replacement or cleaning, significantly reducing the long-term operation and maintenance costs and downtime of the sewage pipe diffuser used for port sewage dilution and diffusion discharge. In addition, the back-pressure valve itself can play a certain role in rectifying the sewage discharge and forming a stable jet, which helps to improve the sewage diffusion effect.

[0029] In some embodiments, the sewage pipe diffuser for diluting and discharging port sewage also includes a wireless water quality monitor 6 for detecting the concentration of pollutants in seawater; a sampling probe of the wireless water quality monitor 6 is mounted above each back pressure check valve 4 and is positioned directly above the valve port of the back pressure check valve 4.

[0030] A wireless water quality monitor 6 is installed at a fixed distance directly above the valve port of each back-pressure check valve 4, with its probe facing the initial mixing zone of the sewage plume. This arrangement allows for real-time and continuous capture of the initial mixing effect of sewage and seawater discharged from the riser 2, i.e., near-field dilution, as well as changes in the concentration of key pollutants such as chemical oxygen demand (COD), ammonia nitrogen, and suspended solids. Wireless transmission eliminates the need for complex submarine cable laying, improving reliability and deployment flexibility. The real-time data from the wireless water quality monitor 6 has multiple functions: 1) Operational monitoring: Operators can remotely monitor whether the discharge from each riser 2 is normal and uniform, and promptly detect blockages in individual valves or abnormal flow rates. 2) Model calibration and optimization: Feedback data can be used to verify and calibrate hydrodynamic-water quality models that predict pollutant diffusion, making future discharge scheme designs and flow allocation more accurate. 3) Environmental impact assessment and early warning: Continuous monitoring data can form an objective chain of evidence of emission impact. When the dilution and diffusion of pollutants do not reach the expected level or when abnormalities occur, timely warnings can be issued to assist management departments in decision-making, truly realize the "visibility, controllability and traceability" of the emission process, and improve the intelligence and environmental safety of the entire wastewater discharge system.

[0031] After the wastewater is ejected from risers 2 with different spacing and number, it first goes through the initial stage of solution ejection, moving along the upward direction of the outflow under the action of initial momentum; then it goes through the stage of rapid concentration reduction, the jet bends and gradually bifurcates under the action of the pressure difference before and after, and finally rises slowly under the influence of buoyancy; during this process, as the lateral expansion width of the jet increases, the jets between adjacent risers gradually develop into merging jets, and the spacing of risers 2 has a significant impact on the diffusion range of the experimental solution.

[0032] Therefore, in some embodiments, the spacing s between adjacent risers 2 is designed as follows: the delivery pipe 1 and riser 2 are buried in silty clay in a deep trench area near the shoreline; the back pressure check valve 4 and the anti-backflow structure 5 are close to and higher than the bottom surface of the deep trench area; the depth of the deep trench area is greater than or equal to 10m; the spacing s between adjacent risers 2 satisfies the following formula:

[0033] Where s is the distance between adjacent risers in meters; K is a given coefficient obtained through experiments in the area where the delivery pipes are to be installed. The design flow rate for a single riser is expressed in units of... v is the average flow velocity of seawater in the deep channel, in m / s; d is the inner diameter of the riser, in m.

[0034] The diffuser system is buried in silty clay in a deep trench area near the shoreline, taking advantage of natural geographical and geological conditions. The silty clay layer has a certain degree of stability and erosion resistance, providing solid support for the pipeline and reducing the risk of physical damage caused by seafloor quicksand, foundation settlement, or trawling operations. The deep trench area is usually a naturally strong hydrodynamic area, which is conducive to the rapid transport and diffusion of pollutants.

[0035] The deep channel ensures that the back pressure check valve 4 is at a sufficient water depth, which not only provides a large seawater dilution volume but also reduces the direct impact of sewage discharge on the seabed surface ecosystem, such as plankton and zooplankton, in accordance with the basic principles of deep-sea discharge. At the same time, the requirement that "the back pressure check valve 4 and the anti-backflow structure 5 are close to and higher than the bottom surface of the deep channel area" is to prevent seabed sediments from directly covering or burying the discharge outlet at low flow velocities, ensuring smooth outflow and preventing seabed silt backflow.

[0036] Based on this, using the preset total discharge flow rate, selected pipe diameter, and hydrological data of the expected installation location, the theoretical optimal spacing of risers 2 can be calculated using a formula to balance the following objectives: 1) Avoid premature plume merging: If the spacing is too small, the sewage plumes ejected from adjacent risers 2 will merge prematurely during the rising and diffusion process, reducing the contact area with fresh seawater and lowering the overall dilution efficiency. 2) Ensure continuous coverage area: If the spacing is too large, although the dilution effect of a single plume is good, it may lead to a dilution "blind zone" in the discharge area. 3) Adapt to environmental dynamics: The formula includes the flow velocity v, which means that the spacing design is dynamically adapted to the specific hydrodynamic conditions of the installation point, ensuring that the sewage jet can make full use of the environmental current for diffusion, rather than conflicting with it.

[0037] In some embodiments, when the area where the sewage pipe diffuser for diluting and discharging port sewage is installed has the characteristics of an open nearshore sea area with seawater flow driven mainly by tides and a monsoon climate zone, the value of K ranges from 0.22 to 0.28.

[0038] The range of 0.22-0.28 takes into account the influence of typical monsoon nearshore marine factors such as tidal asymmetry and wind and wave disturbance on the diffusion pattern of sewage plumes, and provides important parameter basis for the design of sewage pipe diffusers for the dilution and diffusion of port sewage in similar marine areas.

[0039] In some embodiments, the delivery pipe 1 is a tapered pipe, and the top end of the tail pipe 12 is the small-diameter end of the delivery pipe 1.

[0040] Wastewater is transported from the land-based pumping station 9 via the main pipe 11, and continuously diverted through various risers 2 along the way. If the main pipe 11 has a constant diameter, the remaining wastewater velocity will continuously decrease due to reduced flow rate and frictional resistance, resulting in insufficient pressure at the end riser 2 and weak outflow. Designing the transport pipe 1 as a tapered pipe effectively maintains or even increases the flow velocity within the pipe while the flow rate decreases by reducing the pipe cross-sectional area. According to Bernoulli's principle, dynamic pressure is maintained, and static pressure is correspondingly regulated. This ensures that the riser 2, located downstream of the transport pipe 1, still has sufficient pressure to overcome the opening resistance of the back pressure valves and the static pressure of the seawater, achieving effective wastewater jetting. This ensures the uniformity of outflow from all risers 2, avoids attenuation of outflow at the end, and provides crucial structural optimization support for achieving pressure balance and uniform discharge from each back pressure valve.

[0041] In some embodiments, the tailpipe 12 includes a bridging section 121 and a guide section 122; the axis of the main pipe 11, the axis of the bridging section 121 and the axis of the guide section 122 are smoothly connected in sequence, the axis of the guide section 122 is a straight line and the axis of the bridging section 121 is an arc.

[0042] The main pipe 11 is laid horizontally on the seabed. The bridging section 121 adopts an arc axis to achieve a smooth and gradual change in the water outlet direction from the main pipe 11 to the guide section 122, which has a certain angle. This smooth, streamlined transition minimizes local eddies, impact losses, and energy dissipation caused by abrupt changes in the flow direction, allowing sewage to smoothly change its flow direction. The guide section 122, as the final outlet section, provides a stable and directional flow channel for the sludge deposited in the conveying pipe 1 with its straight structure, which helps to accelerate the discharge of sludge from the conveying pipe 1 during the flushing of the anti-backflow unit.

[0043] In some embodiments, the angle between the axis of guide segment 122 and the horizontal plane is 30° to 65°.

[0044] The angle between the axis of guide section 122 and the horizontal plane is too small, making it difficult for sediments to be effectively discharged by their own weight and weak water flow, resulting in poor flushing effect of conveying pipe 1. Setting the angle between the axis of guide section 122 and the horizontal plane to 30° to 65° is more reasonable. This allows the gravity component to assist the sediments in moving towards the top of tailpipe 12, while ensuring sufficient vertical momentum for wastewater jetting under normal discharge conditions. This meets the requirements for improving dilution effect in deep-sea discharge, and also provides physical convenience for maintenance and cleaning.

[0045] In some embodiments, the back pressure check valve 4 is a duckbill valve; the length direction of the duckbill valve orifice is perpendicular to the axis of the main pipe 11.

[0046] The duckbill valve, a typical back pressure check valve, has the advantages of simple structure, no moving mechanical parts, corrosion resistance, and anti-clogging. Its working principle utilizes a "duckbill" structure made of elastic material, which opens under internal pressure and closes due to elasticity and external water pressure after the pressure is released.

[0047] During installation, the elongated opening of the duckbill valve is perpendicular to the axis of the main pipe 11. When the duckbill valve is open, the jet profile formed by the sewage is a flat fan or ellipse, with its major axis perpendicular to the main pipe 11. This jet shape allows for more efficient interaction with the tidal current across the main pipe 11, increasing the contact area and shear rate between the jet and the surrounding water, thereby accelerating the mixing and dilution process of sewage and seawater, resulting in better initial dilution.

[0048] In some embodiments, the riser 2 includes a straight pipe section 21 and a tapered pipe section 22. The two ends of the straight pipe section 21 are connected to the main pipe 11 and the large-diameter end of the tapered pipe section 22, respectively, and the small-diameter end of the tapered pipe section 22 is connected to the back pressure check valve 4.

[0049] The tapered section 22, serving as a transition section connecting the straight section 21 and the back-pressure check valve 4, offers advantages similar to the Venturi effect. Wastewater enters the straight section 21 from the main pipe 11 and then flows into a tapered section 22 with a gradually narrowing cross-section. According to fluid mechanics principles, under constant flow conditions, the flow velocity increases as the water flows through the tapered section, and a portion of the static pressure is converted into dynamic pressure. This results in two effects: 1) Increased jet velocity: A higher initial jet velocity is achieved at the outlet of the back-pressure check valve 4, enhancing the penetration and initial momentum of the wastewater into the ambient water body, which helps overcome near-field seawater resistance and forms a more stable jet. 2) Optimized flow pattern at the input back-pressure check valve 4: The tapered flow channel helps stabilize the flow field, reduce turbulence and flow separation, allowing the fluid to flow more smoothly towards the valve. This is beneficial for the stable opening and uniform flow distribution of the back-pressure check valve 4, especially flexible valves like duckbill valves, thus ensuring the stability of the outflow.

[0050] In some embodiments, the taper of the main tube 11 is less than 1°.

[0051] The main pipe 11 has a very gentle taper of less than 1° along the water flow direction, which can accurately adapt to the flow rate reduction pattern after the riser 2 splits along the way. By gradually reducing the pipe diameter, the flow velocity and pressure in the entire main pipe 11 are precisely maintained, minimizing the difference in kinetic energy at the outlet of all risers 2 at the beginning and end. This avoids the problems of insufficient pressure and uneven outflow at the end of traditional equal-diameter pipes from the root, and ensures that the dilution and diffusion effect of all discharge points is consistent to the maximum extent.

[0052] The taper of less than 1° achieves a near-smooth gradual contraction of the pipe diameter, completely avoiding additional resistance losses such as flow separation and local eddies caused by excessively rapid pipe diameter contraction. It can transfer the pressure and kinetic energy of the upstream water to the end riser 2 with almost no loss, maximizing the retention of the initial kinetic energy of the sewage jet outflow, improving near-field dilution and diffusion efficiency, and making energy utilization more efficient.

[0053] The extremely gentle taper of less than 1° has very low requirements for pipe manufacturing, welding, and submarine laying and installation. It is almost no different from the traditional equal-diameter pipe construction process and will not increase the additional manufacturing cost or construction difficulty. At the same time, the extremely gentle shrinkage will not cause stress concentration in the pipe wall. When subjected to internal pressure and submarine soil load for a long time, the structural durability is far superior to that of the large taper design, and the service life is more guaranteed.

[0054] In addition, the extremely gentle taper of less than 1° forms a very small slope at the bottom of the main pipe 11, which will not change the hydraulic distribution and can guide the sediment in the pipe to naturally gather at the tail end. When the anti-backflow structure 5 at the tail end is disassembled for reverse flushing, it is easier to flush out the sediment gathered at the tail end as a whole, reducing the dredging cost and difficulty of long-term operation and maintenance.

[0055] In some embodiments, the backflow prevention unit is a flange cover or a valve.

[0056] The flange cover is the simplest and most reliable physical sealing method. It is connected to the end of the tailpipe 12 by bolts to achieve a seal. It is suitable for the tailpipe 12 as a long-term sealing design, with low cost and good sealing performance.

[0057] Valves, such as manual or automatic control valves, provide flexible operability, enabling rapid opening and closing of the tailpipe 12 before and after the flushing delivery pipe 1.

[0058] In some embodiments, the conveying pipe 1 and the riser 2 are made of Q235B steel pipe, welded steel pipe, or fiberglass reinforced plastic (FRP) pipe, taking into full account the corrosiveness of the seawater environment and sewage media, the corrosiveness of the seabed soil, mechanical strength requirements, and engineering economy. For example, FRP pipe has excellent corrosion resistance, light weight, and good hydraulic performance. Q235B steel pipe, welded steel pipe, and FRP pipe are all mature and reliable engineering pipe materials, ensuring the durability and safety of the diffuser's main structure under long-term seabed service conditions.

[0059] Figure 4 The horizontal axis represents the axial direction of the horizontally arranged drainage tube 8, and the vertical axis represents the horizontal radial direction of the drainage tube 8. Figure 4 The image shows the use of a wireless water quality monitoring device to monitor wastewater through a 1800mm diameter drainage pipe (8). Figure 4 (Lower half) and 2 drainage tubes with a diameter of 1200mm 8 ( Figure 4The results of observation and analysis of different diffusion ranges and concentration distributions in the upper half of the seawater show that the flow velocity in the 1800mm diameter drainage pipe 8 was 1.367 m·s⁻¹, and the flow velocity in the two 1200mm diameter drainage pipes 8 was 1.536 m·s⁻¹. Planar angle analysis using the wireless water quality monitoring instrument 6 revealed that near the discharge point at the end of the drainage pipe 8, the concentration of pollutants output from the 1800mm diameter drainage pipe 8 was higher than that from the 1200mm diameter drainage pipe 8. Over time and with the flow of seawater, the pollutants began to diffuse to the surrounding area; in areas closer to the discharge end of the drainage pipe 8... Within a 0.2m radius of the output end of drainage tube 8, the pollutant concentration decreases relatively slowly, maintaining 60%-70% of the initial concentration after approximately one hour of diffusion. However, within the 0.2 to 1m range, the pollutant concentration exhibits a more pronounced gradient decrease, dropping to approximately 20%-50% of the initial concentration after the same diffusion time. When diffusion extends beyond 1m from the output end of drainage tube 8, the pollutant concentration significantly decreases, with most detection points showing concentrations below 10% of the initial concentration. Comparatively, the 1800mm diameter drainage tube 8 results in a greater pollutant diffusion distance. It can be inferred that a larger diameter drainage tube 8 leads to a higher output pollutant concentration and better pollutant diffusion at the output end.

[0060] Therefore, in some embodiments, the major diameter of the main pipe 11 is greater than or equal to 1200 mm. The diameter of the straight pipe section 21 is 250 to 500 mm. The minor diameter of the top end of the tapered pipe section 22 is 50 mm to 250 mm.

[0061] Figure 5 The horizontal axis represents the axial direction of the horizontally arranged drainage tube 8, and the vertical axis represents the vertical direction. (Reference) Figure 5 In the vertical direction, from the perspective of concentration distribution, due to the density stratification of seawater, pollutants are mainly concentrated in the upper layer of water near the output end of diversion pipe 8; in the first 30 minutes, the 1800mm diameter diversion pipe 8 ( Figure 5 The average concentration of pollutants in the water above the lower half of the outlet is 3-4 times that of the lower water layer; 8 drainage pipes with a diameter of 1200mm. Figure 5 The average concentration of pollutants in the water above the outlet is 2-3 times that of the lower water. As mixing increases, the concentration difference between the upper and lower water layers gradually decreases, but the concentration of pollutants in the upper water layer is always higher than that in the lower water layer throughout the observation period. In the vertical direction, due to the combined effects of water flow and diffusion, the pollutant concentration exhibits a concentric circular distribution that decreases from the outlet to the surrounding areas, with a diffusion distance of 1800 mm in diameter that is significantly longer.

[0062] Specifically, different sea areas have different requirements for initial dilution. The design initial dilution or design standard is proposed based on the characteristic values ​​used. In order to reduce the potential impact of pollution plumes on surrounding protected targets and ensure that the pollutant concentration in the receiving water body meets the Environmental Quality Standard (EQS), the diffuser length and dilution effect satisfy the following formula.

[0063] In the formula: --Diffuser length, in meters (m); 总 --Diffuser wastewater discharge rate, in cubic meters per second (m³ / s) 3 ·s -1 ) ; --Initial dilution, in degrees (D); --The maximum buoyancy height of wastewater, in meters (m), is a value... ; --Surrounding seawater density Take 1025 kg / m 3 ; --Wastewater discharge density, Take 1005 kg / m 3 ; --Reduced gravitational acceleration, in meters per second squared (m / s²) 2 (Take g≈9.80 m / s) 2 ; set up The value is 45D. After calculation, the length of the diffuser tube is... The value is 118m, and the calculation formula is:

[0064] set up The value is 55D. After calculation, the length of the diffuser tube is... The value is 160m, and the calculation formula is:

[0065] set up The value is 80D. After calculation, the length of the diffuser tube is... The value is 280m, and the calculation formula is:

[0066] The selection of wastewater marine treatment discharge points and the design of discharge systems should ensure that the initial dilution meets the initial dilution requirements specified in the table below for a 90% year-round guarantee rate: Initial dilution requirement with 90% time guarantee

[0067] Based on the principle of dilution, the use of diffusers changes the original point-like diffusion state into a linear diffusion state. Generally, the longer the diffuser and the more risers, the better the dilution effect. However, the near-field diffusion range should be larger, and the cost is higher. Therefore, it is necessary to conduct experimental simulations to demonstrate the ideal combination of diffuser length, riser number and spacing to achieve a better dilution effect and a smaller near-field diffusion area.

[0068] Through the description of several embodiments of a sewage pipe diffuser for diluting and discharging port wastewater according to the present invention, it can be seen that the embodiments of the sewage pipe diffuser for diluting and discharging port wastewater according to the present invention have at least one or more of the following advantages: 1. The back-pressure check valve of this invention opens when the sewage pressure pumped to the delivery pipe is high, allowing sewage to spray upwards into the water body. When sewage pumping stops or the pressure inside the main pipe is lower than the external seawater static and dynamic pressure, the back-pressure check valve automatically closes, preventing seawater carrying seabed sediments from flowing back into the sewage discharge diffuser. The detachable design of the back-pressure check valve facilitates its replacement or cleaning, significantly reducing the long-term operation and maintenance costs and downtime of the sewage pipe diffuser used for port sewage dilution and diffusion discharge. Furthermore, the back-pressure valve itself can rectify the sewage discharge and form a stable jet, helping to improve the sewage diffusion effect.

[0069] 2. This invention involves installing a wireless water quality monitoring instrument at a fixed distance directly above the valve port of each back-pressure check valve. The probe of this instrument faces directly towards the initial mixing zone of the sewage plume. This arrangement allows for real-time and continuous capture of the initial mixing effect of the sewage discharged from the riser with seawater, i.e., near-field dilution, as well as changes in the concentrations of key pollutants such as chemical oxygen demand (COD), ammonia nitrogen, and suspended solids. The wireless transmission method eliminates the need for complex submarine cable laying, improving reliability and deployment flexibility.

[0070] 3. This invention, using hydrological data from a preset total discharge flow rate, a selected pipe diameter, and the expected installation location, can calculate the theoretically optimal riser spacing using a formula to balance the following objectives: 1) Avoiding premature plume merging. 2) Ensuring continuous coverage area. 3) The spacing design dynamically adapts to the specific hydrodynamic conditions of the installation point, ensuring that the sewage jet can fully utilize environmental currents for diffusion, rather than conflicting with them.

[0071] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A sewage pipe diffuser for diluting and discharging port sewage, characterized in that, include: The system includes a delivery pipe, risers, a back pressure check valve, and an anti-backflow structure. The delivery pipe consists of a main pipe and a tail pipe. The main pipe has a horizontal axis, and the bottom of the tail pipe is connected to the output end of the main pipe. The top of the tail pipe is detachably connected to an anti-backflow structure for sealing the top of the tail pipe. Multiple risers are welded to the outer wall of the main pipe at equal intervals along the main pipe axis. The top of the risers is detachably connected to a back pressure check valve, and the bottom of the risers is connected to the main pipe.

2. The sewage pipe diffuser for dilution and diffusion of port sewage according to claim 1, characterized in that, It also includes a wireless water quality monitor for detecting the concentration of pollutants in seawater; and a wireless water quality monitor with a sampling probe mounted above each back pressure check valve and facing the valve port of the back pressure check valve.

3. A sewage pipe diffuser for diluting and discharging port sewage according to claim 1, characterized in that, The delivery pipe and riser are buried in the silty clay of the deep trench area near the shoreline; the back pressure check valve and anti-backflow structure are close to and higher than the bottom of the deep trench area; the depth of the deep trench area is greater than or equal to 10m; the spacing s between adjacent risers satisfies the following formula: Where s is the distance between adjacent risers, in meters; K is a given coefficient, in meters; The design flow rate for a single riser is expressed in units of... v is the average flow velocity of seawater in the deep channel, in m / s; d is the inner diameter of the riser, in m.

4. A sewage pipe diffuser for diluting and discharging port sewage according to claim 3, characterized in that, When the area where the sewage pipe diffuser for dilution and diffusion of port sewage is installed has the characteristics of open nearshore waters with seawater flow driven mainly by tides and a monsoon climate zone, the value of K ranges from 0.22 to 0.

28.

5. A sewage pipe diffuser for diluting and discharging port sewage according to any one of claims 1-4, characterized in that, The delivery pipe is a tapered pipe, with the small-diameter end of the tail pipe at the top.

6. A sewage pipe diffuser for diluting and discharging port sewage according to any one of claims 1-4, characterized in that, The tailpipe includes a bridging section and a guide section; the main pipe axis, the bridging section axis, and the guide section axis are smoothly connected in sequence, the guide section axis is a straight line, and the bridging section axis is an arc.

7. A sewage pipe diffuser for dilution and diffusion of port sewage according to claim 6, characterized in that, The angle between the axis of the guide section and the horizontal plane is 30° to 65°.

8. A sewage pipe diffuser for diluting and discharging port sewage according to any one of claims 1-4, characterized in that, The back pressure check valve is a duckbill valve; the length direction of the duckbill valve orifice is perpendicular to the axis of the main pipe.

9. A sewage pipe diffuser for dilution and diffusion discharge of port sewage according to any one of claims 1-4, characterized in that, The riser consists of a straight pipe section and a tapered pipe section. The two ends of the straight pipe section are connected to the main pipe and the large-diameter end of the tapered pipe section, respectively. The small-diameter end of the tapered pipe section is connected to a back pressure check valve.

10. A sewage pipe diffuser for diluting and discharging port sewage according to any one of claims 1-4, characterized in that, The conveying pipe and riser are made of one of the following: Q235B steel pipe, welded steel pipe, or fiberglass reinforced plastic pipe; the backflow prevention unit is a flange cover or valve.

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