Hydro-pad Seal Face Profile for High-Pressure Boiler Pump Seals
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Solution Overview
Problem
Rotary mechanical end face seals in power plant boiler feed water pumps face challenges with high-temperature and high-pressure fluids that are not effective lubricants, leading to steam formation and increased leakage, requiring separate cooling systems for maintenance and reducing seal durability.
Innovation Solution
A rotary end face seal assembly with hydro-pad recesses and feeder grooves on one seal face to enhance fluid penetration and create a hydrodynamic force, maintaining a liquid film for lubrication and reducing friction, eliminating the need for external cooling systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate cooling water flush is provided for the seal, then seal functionality and durability are maintained, but installation and operating expense increase
Solution Approach 1:
The seal assembly uses its own process fluid to cool and lubricate the sealing faces through the hydro-pad recesses and feeder grooves, eliminating the need for external cooling water delivery systems. The process fluid circulating through the seal faces provides self-cooling and self-lubrication, making the system self-sufficient.
Solution Approach 2:
The cooling and lubrication function is extracted from the external cooling water system and integrated directly into the seal assembly structure itself. The hydro-pad recesses and feeder grooves are built into the seal faces, allowing the seal to perform its own cooling and lubrication without external infrastructure.
2Reliability
If hydro-pad recesses and feeder grooves are added to the seal face, then fluid penetration and lubrication are enhanced, but manufacturing complexity increases
Solution Approach 1:
The seal face is designed with hydro-pad recesses and feeder grooves that create a controlled porous-like structure. This allows process fluid to penetrate and distribute evenly across the sealing face, enhancing lubrication while maintaining structural integrity. The recesses act as fluid reservoirs and distribution channels.
3Device complexity
If the seal operates without external cooling, then installation and operating expense decrease, but fluid may flash to steam under high pressure and temperature
Solution Approach 1:
The seal utilizes hydraulic principles by allowing process fluid to penetrate through hydro-pad recesses and feeder grooves, creating a hydrodynamic film between sealing faces. The fluid pressure and flow through the recesses maintain liquid state and provide continuous lubrication, preventing steam formation through hydrodynamic cooling.
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 seal assembly effectively operates without separate cooling water, maintaining durability and controlling leakage under high-pressure and high-temperature conditions by utilizing hydro-pad recesses and feeder grooves to ensure adequate lubrication and fluid retention in a liquid state.
Implementation Method 1
A plurality of hydro-pad recesses are formed radially inwardly from the peripheral edge of one of the seal faces at the pressure side of the seal assembly
Data Source
AI summary
A rotary end face seal assembly to seal a fluid under pressure includes a pair of annular mating ring seal faces with one of the faces defining a sealing interface between radially inner and radially outer peripheral edges. A plurality of hydro-pad recesses are formed radially inwardly from the peripheral edge of one of the seal faces at the pressure side of the seal assembly at peripherally spaced intervals and a plurality of feeder grooves are formed radially inwardly from the same peripheral edge of the seal face between at least some hydro-pad recesses. The radial extent of the feeder grooves is longer than the radial extent of the hydro-pad recesses. In one form a feeder groove is disposed between adjacent hydro-pad recesses. In another form a feeder groove is disposed between adjacent pairs of hydro-pad recesses.