A method for calculating and controlling the pump seal water in the cabin of a trailing suction dredger
By establishing a basic flow model and a dynamic correction method for water sealing calculation based on wear conditions, combined with multi-condition dynamic adaptation and closed-loop feedback regulation, the problem of equipment wear and energy waste in the water sealing system of the trailing suction hopper dredger during multi-condition switching was solved, and dynamic adaptation of water sealing parameters and efficient operation were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CCCC SHANGHAI DREDGING CO LTD
- Filing Date
- 2026-04-03
- Publication Date
- 2026-07-10
AI Technical Summary
In existing technologies, the water sealing system of the pump in the hull of a trailing suction hopper dredger cannot achieve dynamic adaptation of water sealing parameters when switching between multiple working conditions, resulting in equipment wear, energy waste and low construction efficiency. Moreover, traditional control methods cannot meet the requirements of green energy saving.
A basic flow model is established by combining theoretical formulas with the dynamic correlation between impeller diameter and rotational speed. By dynamically correcting the wear state, real-time matching of sealing water flow and pressure is achieved. Combined with multi-condition dynamic adaptation and closed-loop feedback regulation, dynamic adaptation of sealing water parameters and mud pump operating status is realized.
It effectively reduces equipment wear, lowers energy consumption, improves construction efficiency, extends the maintenance cycle of vulnerable parts, meets the needs of complex operations, and conforms to the trend of green ship development.
Smart Images
Figure CN122364594A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of pump technology for trailing suction hopper dredgers, specifically a calculation method and control method for water sealing in the pump of a trailing suction hopper dredger. Background Technology
[0002] The mud pump sealing system consists of shaft end sealing water and suction end sealing water. The sealing water is provided by the sealing water pump. Its core functions include: providing water lubrication and flushing protection for the mud pump shaft seal, preventing mud and sand from entering the shaft end and suction end sealing gap; providing balance water for the inner and outer tanks of the double-casing pump, reducing the pressure and deformation of the inner tank; and reducing wear between the pump blades and the pump body through flushing action, ensuring the long-term stable operation of the mud pump.
[0003] The shaft-side sealing water is divided into three paths: one enters through the sealing box interface to prevent mud from entering the sealing box; one enters the water seal device through the sand-water separator to ensure good lubrication of the shaft seal; and one enters between the inner and outer pump casings through the interface on the outer pump casing to balance the pressure difference between the inner and outer pump casings. The suction-side sealing water enters the water seal chamber inside the small pump cover to prevent mud from entering the suction end water seal chamber. The sealing water flow rate and pressure must meet the technical requirements of the mud pump during loading and discharge operations, and fully consider the sealing water flow requirements after wear of the front and rear liner gaps of the mud pump. Flow sensors and pressure sensors are usually installed on the sealing water pipeline for parameter monitoring. The sand-water separator adopts a shell-and-tube structure, is made of carbon steel, and is equipped with a stainless steel automatic vent valve and sight glass to ensure that the water quality and flow rate meet the requirements for shaft seal use.
[0004] As trailing suction hopper dredgers develop towards larger and higher power, the in-chamber pump, as a core dredging equipment, often faces complex operational demands such as long discharge distances, high lift, and multiple operating conditions (e.g., switching between constant torque / constant power conditions and switching between different dredging depths). Its operating environment is harsh, with the pump chamber filled with slurry containing solid particles, which easily leads to wear of the shaft end seal and suction port seal, as well as slurry backflow into the impeller clearance, causing equipment damage and reduced operating efficiency. The sealing water system, as a key protective device for the in-chamber pump, directly determines the operational safety and service life of the in-chamber pump through its parameter matching accuracy and control stability.
[0005] Currently, the industry's calculation of sealing water flow rate largely relies on traditional empirical formulas, failing to fully consider the impact of impeller wear-induced clearance changes and speed fluctuations under various operating conditions on sealing water demand. This leads to unreasonable safety margin settings: too small a margin results in ineffective leak prevention, while too large a margin causes energy waste and excessive equipment wear. In terms of control methods, the mainstream approach uses two-speed regulation (high and low) or mud pump speed curve fitting control. These methods suffer from adjustment lag, inability to adapt to dynamic changes under various operating conditions, and reliance on manual intervention, increasing operator workload. Furthermore, they struggle to balance the coordination and matching of sealing water pressure and flow rate, resulting in insufficient sealing system efficiency, frequent pump maintenance within the chamber, and severely impacting construction efficiency.
[0006] Furthermore, traditional water sealing systems lack a dynamic correlation mechanism with the pump speed, operating mode, and component wear status within the dredging chamber. When the pump switches between constant torque (10%-100% of rated speed) and constant power (100%-120% of rated speed) operating conditions, or when the dredging depth is adjusted in different ranges such as within 45m, 45m-70m, and 70m-120m, the water sealing parameters cannot respond in real time. This further exacerbates equipment wear and energy waste, making it difficult to meet the technical requirements of modern dredging projects for green energy saving, high efficiency, and stability.
[0007] Therefore, a calculation method and a control method for the water sealing of the pump in the hull of a trailing suction hopper dredger are provided. Summary of the Invention
[0008] To address the aforementioned problems in the existing technology, this invention provides a calculation method and control method for the water sealing of the pump in the hull of a trailing suction hopper dredger, thereby achieving dynamic adaptation of the water sealing parameters to the pump's operating status.
[0009] The technical solution to achieve the above objectives is: One of the present inventions provides a method for calculating the water seal of the pump inside the hull of a trailing suction hopper dredger, comprising: Step S1: Using theoretical formulas as the basis for calculating sealing flow rate, and considering the dynamic relationship between impeller diameter and rotational speed, a basic flow model matching the impeller geometric parameters and operating status is established. Step S2: Based on the output reference flow rate, and according to the wear state of the impeller-liner gap, select a dynamic coefficient to correct the flow rate and dynamically compensate for the reduction in sealing performance caused by wear. Step S3 involves calculating the corrected flow rate to match the sealing pressure, ensuring that the sealing pressure always suppresses the mud backflow force, thereby achieving dynamic adaptation between the sealing parameters and the mud pump operating status.
[0010] Preferably, in step S1, the reference flow rate Calculation formula: ; In the formula, The diameter of the pump impeller inside the chamber. This refers to the actual rotational speed of the pump impeller inside the chamber.
[0011] Preferably, in step S1, the reference flow formula is applicable to the calculation of sealing water at the shaft end and suction end of the pump in the double-hull chamber, and the reference sealing water flow at the suction end is 1.5 times that at the shaft end.
[0012] Preferably, in step S2, a dynamic safety margin coefficient is selected based on the wear condition of the impeller-liner clearance. Corrected flow rate, corrected sealing flow rate The calculation formula is: ; Among them, safety margin coefficient The improvement increases in a stepwise manner as the clearance between the impeller and the liner increases: Design clearance condition, i.e. 2.5mm: ; Wear clearance condition, i.e. 3.5mm-4.5mm: ; Limit clearance condition, i.e., 5mm: .
[0013] Preferably, in step S3, the sealing pressure is... The calculation formula is: ; In the formula, The actual mud pressure at the pump shaft end or suction port end inside the chamber is dynamically calculated using real-time operating data, operating mode, and discharge pressure characteristic curves of the pump inside the chamber. For a safe pressure differential, the shaft end should be 0.1-0.2 MPa and the suction end should be 0.2-0.3 MPa.
[0014] Preferably, in step S3, the safety pressure difference The value is dynamically adjusted based on the risk of mud backflow at the sealing location, i.e., the shaft end or the suction end, where the pressure difference at the suction end is higher than that at the shaft end.
[0015] A second invention provides a method for controlling the sealing of pumps inside the hold of a trailing suction hopper dredger, comprising: Step T1, Dynamic Adaptation for Multiple Operating Conditions: Based on the pump speed range in the chamber, divide the speed range into multiple speed ranges, and combine the corrected sealing water flow rate calculation value to preset the reference parameters for each range; Step T2, closed-loop feedback adjustment: The actual flow rate is monitored in real time by the flow meter, and the actual pressure is monitored by the pressure sensor. The actual values are compared with the preset values to dynamically optimize the reference parameters and safety margin coefficient. This enables three-dimensional coordinated control of flow rate, pressure, and wear conditions.
[0016] Preferably, in step T1, the 109-328 rpm is divided into multiple control gear ranges, and the sealing pump speed, frequency, head and shaft power parameters of each range are preset. Operating condition strategies include: Constant torque operation: Maintain constant flow rate through PID control; Constant power operation: Simultaneously increase flow rate and pressure.
[0017] Preferably, in step T2, when the actual flow rate is different from the set sealing flow rate... When the flow rate differs by 5%, PID correction is triggered to ensure the flow rate remains stable within the set range. Simultaneously, the sealing pressure parameter is referenced to achieve coordinated matching of flow rate and pressure, specifically including: Real-time acquisition of sealing water flow rate, sealing water pressure, pump speed in the chamber, and pump chamber pressure data at the shaft end / suction port; By comparing the actual flow rate with the set flow rate for the interval, the deviation and the rate of change of deviation are obtained; Based on the fuzzy membership degree of the deviation and the rate of change of deviation, and combined with the stimulus-inhibition mechanism of immune feedback, the proportional coefficient, integral coefficient and derivative coefficient of the PID controller are dynamically adjusted. The speed of the sealing water pump is adjusted by controlling the frequency converter driver through PLC to stabilize the sealing water flow at the set value, while ensuring that the sealing water pressure meets the matching requirements.
[0018] Preferably, in step T2, the impeller-liner clearance is manually checked by periodically disassembling and inspecting the mud pump, and the safety margin factor is automatically adjusted. Wear compensation is performed.
[0019] Compared with the prior art, the beneficial effects of the present invention are: This invention combines theoretical formulas with dynamic wear correction, fully considers the impact of speed changes under multiple operating conditions, and achieves a sealing water flow matching error of ≤5%, effectively avoiding equipment wear caused by under-sealing or energy waste caused by over-sealing. This invention reduces the energy consumption of the sealing pump by 15%-20% compared to traditional high and low speed control through precise matching of speed and flow rate and frequency conversion control, thereby reducing ineffective equipment losses and conforming to the trend of green ship development. This invention effectively prevents the wear of sealing components by mud, extends the maintenance cycle of vulnerable components such as shaft seals and liners by more than 60%, reduces the frequency of construction interruptions, and improves the efficiency of engineering construction. This invention is compatible with double-hull in-hull pumps of different power levels, covering various operation scenarios such as shallow water areas within 45m, medium-deep water areas of 45m-70m, ultra-deep water areas of 70m-120m, and long-distance dredging and backfilling, meeting the complex operation needs of intelligent trailing suction hopper dredgers. Attached Figure Description
[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of a calculation method for water sealing of the pump inside the hull of a trailing suction hopper dredger according to the present invention; Figure 2 This is a flowchart of a method for controlling water sealing of an in-hull pump in a trailing suction hopper dredger according to the present invention. Detailed Implementation
[0021] The technical solutions of 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] like Figure 1 As shown, a method for calculating the pump seal water in the hull of a trailing suction hopper dredger includes: Step S1: Using theoretical formulas as the basis for calculating the sealing flow rate, and considering the dynamic relationship between impeller diameter and rotational speed, a basic flow model matching the impeller geometric parameters and operating status is established.
[0023] In the embodiment, the reference flow rate Calculation formula: ; In the formula, The diameter of the pump impeller inside the chamber. This refers to the actual rotational speed of the pump impeller inside the chamber.
[0024] In this embodiment, the reference flow rate formula is applicable to the calculation of sealing water at the shaft end and suction end of the pump in the double-hull chamber, and the reference sealing water flow rate at the suction end is 1.5 times that at the shaft end.
[0025] Step S2: Based on the output reference flow rate, and according to the wear state of the impeller-liner gap, select a dynamic coefficient to correct the flow rate and dynamically compensate for the reduction in sealing performance caused by wear.
[0026] In this embodiment, a dynamic safety margin coefficient is selected based on the wear condition of the impeller-liner clearance. Corrected flow rate, corrected sealing flow rate The calculation formula is: ; Among them, safety margin coefficient The improvement increases in a stepwise manner as the clearance between the impeller and the liner increases: Design clearance condition, i.e. 2.5mm: It can meet the sealing requirements and reserve a certain wear redundancy; Wear clearance condition, i.e. 3.5mm-4.5mm: It is suitable for water sealing requirements under moderate wear conditions; Limit clearance condition, i.e., 5mm: This ensures that no mud enters the impeller gap.
[0027] Step S3 involves calculating the corrected flow rate to match the sealing pressure, ensuring that the sealing pressure always suppresses the mud backflow force, thereby achieving dynamic adaptation between the sealing parameters and the mud pump operating status.
[0028] In this embodiment, the sealing water pressure must be higher than the mud pressure at the corresponding part of the pump inside the chamber to ensure effective injection of sealing water and prevent mud backflow. The calculation formula is: ; In the formula, The actual mud pressure at the pump shaft end or suction port end is obtained through dynamic calculation using real-time operating data (constant torque / constant power), operating mode (loading / bank blowing), and discharge pressure characteristic curves of the pump. For a safe pressure differential, the shaft end is set at 0.1-0.2 MPa and the suction end at 0.2-0.3 MPa to ensure reliable sealing.
[0029] In the embodiment, the safety pressure difference The value is dynamically adjusted based on the risk of mud backflow at the sealing location, i.e., the shaft end or the suction end, where the pressure difference at the suction end is higher than that at the shaft end.
[0030] like Figure 2 As shown, a method for controlling the water seal of the pump inside the hull of a trailing suction hopper dredger includes: Step T1, Dynamic Adaptation for Multiple Operating Conditions: Based on the pump speed range in the chamber, divide the speed range into multiple speed ranges, and combine the corrected sealing water flow rate calculation value to preset the reference parameters for each range.
[0031] In this embodiment, the 109-328 rpm range is divided into multiple control ranges, and the pump speed, frequency, head and shaft power parameters of each range are preset. Operating condition strategies include: Constant torque operation: The flow rate is kept constant by PID control, and the flow rate fluctuation is suppressed by the PID algorithm to prevent mud from entering. Constant power operation: Simultaneously increase flow rate and pressure, with the pressure increase being no less than 1.2 times the increase in pump chamber pressure, to ensure sealing performance under high pressure conditions.
[0032] The sealing water pump adopts a stepless speed regulation mode, with the sealing water flow rate as the objective function, and automatically adjusts the operating parameters according to the changes in the mud pump speed. The specific matching relationship is as follows (taking a 4500 cubic meter trailing suction hopper dredger as an example): Based on the stepless speed regulation of the sealing water pump, in order to achieve precise control, the sealing water flow rate is used as the objective function. Several speed ranges are set according to the changes in the mud pump speed, and the sealing water flow rate of each range is set accordingly.
[0033] When the mud pump speed changes, the sealing water pump automatically adjusts its speed according to the sealing water flow rate within the mud pump speed range to achieve the required flow rate. The sealing water flow rate can be set according to a theoretical formula. Multiplied by a certain safety margin factor (1.5-1.7).
[0034] The operating frequency of the variable frequency motor for the shaft end and suction end sealing water pump of the 4500 cubic meter vessel is 30-50 Hz. The variable frequency mud pump motor has a 100% speed of 1000 rpm and a minimum starting speed of 300 rpm. After passing through the gearbox, the minimum speed of the mud pump is 109 rpm. Speed increments of 10 rpm are selected, and the impeller diameter is 1.79 m. This is calculated using theoretical formulas. Where D is the impeller diameter, n is the impeller speed, and the value is multiplied by a safety margin factor of 1.5. The theoretical traffic demand is derived, as shown in Tables 1 and 2: Table 1 Calculation of Mud Pump Shaft End Seal Water Flow Rate Table 2 Calculation of water sealing at the suction end of mud pump Step T2, closed-loop feedback adjustment: The actual flow rate is monitored in real time by the flow meter, and the actual pressure is monitored by the pressure sensor. The actual values are compared with the preset values to dynamically optimize the reference parameters and safety margin coefficient. This enables three-dimensional coordinated control of flow rate, pressure, and wear conditions.
[0035] In the embodiment, when the actual flow rate is different from the set sealing flow rate... When the flow rate differs by 5%, PID correction is triggered to ensure the flow rate remains stable within the set range. Simultaneously, the sealing pressure parameter is referenced to achieve coordinated matching of flow rate and pressure, specifically including: Real-time acquisition of sealing water flow rate, sealing water pressure, pump speed in the chamber, and pump chamber pressure data at the shaft end / suction port; By comparing the actual flow rate with the set flow rate for the interval, the deviation and the rate of change of deviation are obtained; Based on the fuzzy membership degree of the deviation and the rate of change of deviation, and combined with the stimulus-inhibition mechanism of immune feedback, the proportional coefficient, integral coefficient and derivative coefficient of the PID controller are dynamically adjusted. The speed of the sealing water pump is adjusted by controlling the frequency converter driver through PLC to stabilize the sealing water flow at the set value, while ensuring that the sealing water pressure meets the matching requirements.
[0036] In this embodiment, the clearance between the impeller and the liner is manually checked by periodically disassembling and inspecting the mud pump, and the safety margin factor is automatically adjusted. Wear compensation is performed to effectively avoid equipment wear caused by under-sealing or energy waste caused by over-sealing.
[0037] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for calculating the water seal of the pump inside the hull of a trailing suction hopper dredger, characterized in that, include: Step S1: Using theoretical formulas as the basis for calculating sealing flow rate, and considering the dynamic relationship between impeller diameter and rotational speed, a basic flow model matching the impeller geometric parameters and operating status is established. Step S2: Based on the output reference flow rate, and according to the wear state of the impeller-liner gap, select a dynamic coefficient to correct the flow rate and dynamically compensate for the reduction in sealing performance caused by wear. Step S3 involves calculating the corrected flow rate to match the sealing pressure, ensuring that the sealing pressure always suppresses the mud backflow force, thereby achieving dynamic adaptation between the sealing parameters and the mud pump operating status.
2. The calculation method for pump sealing in the hull of a trailing suction hopper dredger according to claim 1, characterized in that, In step S1, the reference flow rate Calculation formula: ； In the formula, The diameter of the pump impeller inside the chamber. This refers to the actual rotational speed of the pump impeller inside the chamber.
3. The calculation method for pump sealing in the hull of a trailing suction hopper dredger according to claim 1, characterized in that, In step S1, the reference flow formula is applicable to the calculation of sealing water at the shaft end and suction end of the pump in the double-hull chamber, and the reference sealing water flow at the suction end is 1.5 times that at the shaft end.
4. The calculation method for pump sealing in the hull of a trailing suction hopper dredger according to claim 2, characterized in that, In step S2, a dynamic safety margin coefficient is selected based on the wear condition of the impeller-liner clearance. Corrected flow rate, corrected sealing flow rate The calculation formula is: ； Among them, safety margin coefficient The improvement increases in a stepwise manner as the clearance between the impeller and the liner increases: Design clearance condition, i.e. 2.5mm: ; Wear clearance condition, i.e. 3.5mm-4.5mm: ; Limit clearance condition, i.e., 5mm: .
5. The calculation method for pump sealing in the hull of a trailing suction hopper dredger according to claim 1, characterized in that, In step S3, the sealing water pressure The calculation formula is: ； In the formula, The actual mud pressure at the pump shaft end or suction port end inside the chamber is dynamically calculated using real-time operating data, operating mode, and discharge pressure characteristic curves of the pump inside the chamber. For a safe pressure differential, the shaft end should be 0.1-0.2 MPa and the suction end should be 0.2-0.3 MPa.
6. The method for calculating the water seal of the pump inside the hull of a trailing suction hopper dredger according to claim 5, characterized in that, In step S3, the safety pressure difference The value is dynamically adjusted based on the risk of mud backflow at the sealing location, i.e., the shaft end or the suction end, where the pressure difference at the suction end is higher than that at the shaft end.
7. A method for controlling the water seal of the pump inside the hull of a trailing suction hopper dredger, based on the calculation method for water seal of the pump inside the hull of a trailing suction hopper dredger as described in claims 1-6, characterized in that, include: Step T1, Dynamic Adaptation for Multiple Operating Conditions: Based on the pump speed range in the chamber, divide the speed range into multiple speed ranges, and combine the corrected sealing water flow rate calculation value to preset the reference parameters for each range; Step T2, closed-loop feedback adjustment: The actual flow rate is monitored in real time by the flow meter, and the actual pressure is monitored by the pressure sensor. The actual values are compared with the preset values to dynamically optimize the reference parameters and safety margin coefficient. This enables three-dimensional coordinated control of flow rate, pressure, and wear conditions.
8. The method for controlling the water seal of the pump in the hull of a trailing suction hopper dredger according to claim 7, characterized in that, In step T1, the 109-328 rpm range is divided into multiple control gear ranges, and the sealing pump speed, frequency, head and shaft power parameters of each range are preset. Operating condition strategies include: Constant torque operation: Maintain constant flow rate through PID control; Constant power operation: Simultaneously increase flow rate and pressure.
9. A method for controlling the sealing of the pump in the hold of a trailing suction hopper dredger according to claim 7, characterized in that, In step T2, when the actual flow rate is different from the set sealing flow rate... When the flow rate differs by 5%, PID correction is triggered to ensure the flow rate remains stable within the set range. Simultaneously, the sealing pressure parameter is referenced to achieve coordinated matching of flow rate and pressure, specifically including: Real-time acquisition of sealing water flow rate, sealing water pressure, pump speed in the chamber, and pump chamber pressure data at the shaft end / suction port; By comparing the actual flow rate with the set flow rate for the interval, the deviation and the rate of change of deviation are obtained; Based on the fuzzy membership degree of the deviation and the rate of change of deviation, and combined with the stimulus-inhibition mechanism of immune feedback, the proportional coefficient, integral coefficient and derivative coefficient of the PID controller are dynamically adjusted. The speed of the sealing water pump is adjusted by controlling the frequency converter driver through PLC to stabilize the sealing water flow at the set value, while ensuring that the sealing water pressure meets the matching requirements.
10. A method for controlling the sealing of the pump in the hold of a trailing suction hopper dredger according to claim 7, characterized in that, In step T2, the clearance between the impeller and the liner is manually checked and the safety margin factor is adjusted by periodically disassembling and inspecting the mud pump. Wear compensation is performed.