Porous Separation Seal for Reduced Buffer Gas Supply
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Solution Overview
Problem
Existing dry gas seals in centrifugal compressors face challenges in preventing lubricant oil from entering the seal, particularly when the buffer gas supply is reduced, which can lead to contact between the rotating and stationary rings, causing wear and leakage.
Innovation Solution
A separation seal design featuring a porous primary ring and a mating ring with grooves, where pressurized buffer gas is conveyed through the primary ring control chamber to create a gas film between the rings, and the grooves pump gas from the inner to the outer diameter to maintain separation even with reduced buffer gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a typical separation seal with buffer gas injection is used, then lubricant oil is prevented from entering the dry gas seal, but the seal requires continuous pressurized buffer gas supply and becomes vulnerable when gas supply is reduced
Solution Approach 1:
The grooves are pre-formed on the mating ring surface to create a pump action that activates automatically when buffer gas supply is reduced, drawing gas from the high-pressure side to the low-pressure side to maintain the gas film and prevent ring contact before failure occurs
Solution Approach 2:
The grooves act as an intermediary mechanism between the buffer gas supply system and the seal interface, providing an alternative gas transport path that maintains separation when the primary buffer gas supply is insufficient
2Loss of energy
If the buffer gas supply is reduced to save energy or reduce operating costs, then energy consumption is lowered, but the rings may contact each other causing wear and leakage
Solution Approach 1:
The grooves on the mating ring create a self-activating pump mechanism that automatically draws buffer gas from the high-pressure region to the low-pressure region when supply is reduced, maintaining the gas film and preventing ring contact without external control or additional energy input
3Reliability
If a porous primary ring is used with grooves on the mating ring, then the seal maintains effectiveness under reduced buffer gas supply, but the device complexity increases
Solution Approach 1:
The primary ring is made of porous material that allows buffer gas to pass through it, creating a pump action that draws gas from the high-pressure side to the low-pressure side, enhancing the seal's ability to maintain the gas film under reduced buffer gas supply conditions
Solution Approach 2:
The mating ring face is segmented into multiple grooves that create individual pump channels, distributing the gas pumping function across multiple pathways to ensure reliable gas film maintenance while managing the complexity through standardized geometric features
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 solution effectively prevents lubricant oil from entering the dry gas seal, maintains a non-contacting regime to prevent wear, and ensures a positive restriction to prevent leakage of pressurized gas, even under conditions of reduced buffer gas supply.
Implementation Method 1
a porous primary ring formed of a porous material... gas passes from the back of the porous primary ring, through the porous primary ring and to the seal interface
Implementation Method 2
the grooves pumps gas from an inner diameter of the seal interface to an outer diameter of the seal interface
Implementation Method 3
one or more biasing members that urges the porous primary ring toward the mating ring to form a seal interface
Data Source
Figure 1
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AI summary
A seal includes a mating ring (114) that rotates relative to a porous carbon primary ring (116) at a seal interface. A buffer gas is provided into the seal and passes from the back of the primary ring to the seal interface. The seal can be used as a separation seal or in combination with another seal.