Nuclear Coolant Pump Seal Staging for Pressure Drop and Wear Control
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Solution Overview
Problem
Nuclear power generation facility coolant pumps face challenges in achieving a balance between effective sealing and longevity, as increased sealing pressure leads to wear and potential leakage, while also requiring regulatory compliance to prevent radioactive material leakage.
Innovation Solution
A coolant pump design featuring a gland housing with a staging flow pathway and rotor assembly that accelerates fluid through seal stages, using static and rotating sealing elements to form a fluid-tight seal, with multiple stages configured to divide pressure drops and control fluid velocity and pressure to optimize seal performance and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If increased sealing pressure is applied to maintain pressure differential across the seal, then sealing effectiveness is improved, but wear of sealing elements increases
Solution Approach 1:
The seal is divided into multiple seal stages (first seal stage and second seal stage) arranged in series. Each stage handles a portion of the total pressure differential, so that no single sealing element pair must withstand the full pressure difference. This segmentation allows each seal to operate at lower pressure differentials, reducing wear while maintaining overall sealing effectiveness.
Solution Approach 2:
The seal design incorporates fluid velocity and pressure dynamics to balance seal effectiveness and longevity. By considering fluid conditions proximate to each seal stage and optimizing the pressure differential distribution across stages, the system dynamically balances the trade-off between maintaining tight seals and minimizing wear on sealing elements.
2Reliability
If higher pressure differential is maintained across a seal, then sealing performance is improved, but fluid velocity effects may destabilize sealing
Solution Approach 1:
The total pressure differential is segmented across multiple seal stages, with each stage handling a controlled portion of the pressure drop. This prevents any single seal from experiencing excessive pressure differentials that could be destabilized by fluid velocity effects, while collectively maintaining high overall sealing performance.
Solution Approach 2:
The design optimizes fluid velocity and pressure parameters proximate to each seal stage to ensure stable sealing operation. By controlling fluid conditions and pressure differential distribution across stages, the system maintains sealing performance while avoiding instability caused by excessive fluid velocity effects.
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 design achieves a balanced seal performance and longevity by evenly distributing pressure drops across multiple stages, reducing wear and leakage, while maintaining regulatory compliance and ensuring consistent sealing effectiveness.
Implementation Method 1
a rotor assembly pumping a coolant fluid through the gland housing, the rotor assembly having an acceleration surface, wherein fluid passing through the staging flow pathway is accelerated by the acceleration surface
Implementation Method 2
first and second seal stages within the first and second seal chambers, each having a static sealing element and a rotating sealing element, the sealing elements engaging one another to form a fluid-tight seal
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A seal assembly for a pump comprises a gland housing mounted to the pump casing. A staging flow pathway is defined within the gland housing with multiple seal chambers. A seal stage is positioned in each seal chamber, each having a static sealing element and a rotating sealing element, the sealing elements engaging one another to form a fluid-tight seal. A rotor assembly pumps coolant through the gland housing. Fluid passing through the staging flow pathway is accelerated by an acceleration surface of the rotor assembly. An inlet passage feeds coolant fluid into the staging flow pathway and past the acceleration surface.