Shaft Seal Recirculation for Dredge Pump Water Reduction
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Solution Overview
Problem
Current shaft seal systems in dredge pumps are inefficient in terms of water usage, power consumption, and complexity, especially when multiple pumps are assembled in series, and they often fail to withstand high pressure differences and dynamic loads.
Innovation Solution
A shaft seal system comprising a mechanical seal and a lip seal positioned at different axial locations around the drive shaft, with a fluid supply to maintain a controlled pressure in the chamber between them, allowing for recirculation of fluid and reduced water usage, and capable of withstanding high pressure differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shaft seal system uses high pressure water to flush the sealing chamber and transport particles away, then the lip seals are protected from particle damage and friction is reduced, but water consumption increases significantly and the system becomes complex
Solution Approach 1:
The patent recycles the water that has passed through the sealing chamber by directing it back into the chamber through inlet holes in the drive shaft. This closed-loop system allows the same water to continuously flush the sealing area and carry particles away without requiring constant fresh water supply, thereby reducing overall water consumption while maintaining seal protection.
Solution Approach 2:
The water supplied to the sealing chamber serves multiple functions simultaneously: it acts as a barrier to prevent particles from reaching the lip seals, provides lubrication to reduce friction between the seal and shaft, and creates a pressure differential to maintain sealing effectiveness. This multi-functionality reduces the need for separate systems for each purpose.
2Reliability
If clean water is supplied at high pressure to the sealing chamber to prevent particle ingress, then the lip seals remain intact and functional, but the system requires an expansive and complex clean water supply infrastructure
Solution Approach 1:
The drive shaft itself is designed with inlet holes that allow water to be supplied directly to the sealing chamber. This integrates the water supply function into the existing shaft structure, eliminating the need for separate complex supply infrastructure. The system uses its own components to deliver the necessary flushing action.
Solution Approach 2:
The water in the sealing chamber acts as an intermediary barrier between the particles in the pumped mixture and the lip seals. By maintaining a controlled water environment in the chamber, particles are prevented from directly contacting the seals, while the water can be continuously refreshed through the shaft's inlet holes without requiring complex external supply systems.
3Productivity
If multiple dredge pumps are assembled in series with traditional shaft seal systems, then the pumping capacity increases, but the complexity and cost of sealing systems multiply and become unacceptable
Solution Approach 1:
The shaft seal system is divided into distinct functional segments: the mechanical seal for primary sealing, the lip seal for secondary sealing, and the flushing chamber for particle removal. Each segment can be independently optimized and maintained. This modular segmentation allows the system to be replicated in series pumps without proportionally increasing overall system complexity, as each pump unit contains a complete but simplified sealing package.
4Stress or pressure
If traditional shaft seal systems are used in dredge pumps operating under high pressure differences, then the seals may fail to withstand the pressure load, but simpler seal designs cannot maintain sealing effectiveness
Solution Approach 1:
Water is supplied to the sealing chamber before particles can reach the lip seals, creating a protective water barrier in advance. This preliminary flushing action prevents particles from accumulating at the seal interface and ensures that the sealing surfaces remain clean and effective even under high pressure differential conditions.
Solution Approach 2:
The patent combines a mechanical seal (for handling high pressure differences) with a lip seal (for particle protection). The mechanical seal's rigid sealing surfaces are specifically designed to withstand the high pressure differential between the pump inlet and outlet, while the lip seal provides an additional flexible barrier. This substitution of seal types for different functional requirements resolves the contradiction between pressure withstand capability and sealing effectiveness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system reduces fluid consumption, maintains seal integrity under high pressures, and is cost-effective and durable, minimizing fluid leakage and mixture dilution while handling dynamic loads effectively.
Implementation Method 1
a first seal (10) being a mechanical seal positioned between a high pressure area and a chamber and the second seal (20) being a lip seal
Implementation Method 2
with a fluid supply to maintain a controlled pressure in the chamber between them
Implementation Method 3
allowing for recirculation of fluid and reduced water usage
Data Source
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AI summary
The invention relates to a shaft seal (1), arranged to seal a rotatable drive shaft (2) from a high pressure area. The shaft seal (1) comprises a shaft seal housing (3), a first seal (10) and a second seal (20), wherein the first and second seals (10, 20) are positioned around the drive shaft (2) at different axial positions. A chamber (4) is created in between the first (10) and second seal (20), wherein the shaft seal (1) comprises a fluid supply (74 –78) for supplying a pressurized fluid to the chamber (4). The first seal (10) is a mechanical seal positioned between the high pressure area and the chamber and the second seal (20) is a lip seal.