Steam Turbine Shut-Off Valve Grooves to Prevent Control Oil Sludge
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Solution Overview
Problem
Conventional emergency shut-off devices for steam turbines face issues with sludge formation due to stagnation and deterioration of control oil, which can clog piston valves and prevent proper operation during emergencies.
Innovation Solution
Incorporating spiral or linear grooves on the sliding surfaces of piston valves to intentionally leak control oil, preventing stagnation and sludge formation, while maintaining reliable operation by ensuring the grooves are 1.0 mm or less in depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If control oil is completely sealed in chambers to maintain pressure, then pressure stability is improved, but sludge formation increases due to stagnation
Solution Approach 1:
The piston valve sliding surface is designed with groove structures that function as controlled porous pathways. These grooves allow minimal oil leakage while maintaining overall pressure stability, preventing sludge formation by enabling oil circulation without compromising the sealing function.
Solution Approach 2:
The groove structures enable continuous minimal oil flow through the piston valve sliding surfaces, preventing oil stagnation and sludge formation. This continuous action maintains pressure stability while eliminating the harmful effect of complete sealing.
2Reliability
If grooves are added to piston valve sliding surfaces to prevent sludge, then reliability is improved, but pressure loss increases due to leakage
Solution Approach 1:
The groove structures are localized to specific areas of the piston valve sliding surfaces, creating controlled leakage pathways only where needed. This local modification prevents sludge formation at critical interfaces while maintaining pressure stability in the overall chamber system.
Solution Approach 2:
The groove dimensions (depth, width, spacing) are optimized to control the leakage rate. By adjusting these parameters, the design achieves minimal pressure loss while sufficient oil circulation to prevent sludge formation, balancing reliability improvement with energy conservation.
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 reduces the occurrence of sludge, enhancing the reliability of trip operations and maintaining minimal pressure loss, ensuring the emergency shut-off device functions correctly even under varying conditions.
Implementation Method 1
a sliding surface of each of the piston valves has a groove to leak the control oil in the chambers
Implementation Method 2
a spring which applies a biasing force to the piston
Implementation Method 3
the control oil is supplied to and drained from a chamber
Data Source
AI summary
An emergency shut-off device shuts off supply of control oil to a trip-and-throttle valve of a steam turbine and closes the trip-and-throttle valve in an emergency. The emergency shut-off device includes: a cylinder; a piston that slides into the cylinder; a spring that applies a biasing force to the piston; a plurality of piston valves disposed on the piston; and a plurality of chambers that are formed by the piston valves. The control oil is supplied to and drained from the plurality of chambers, and a sliding surface of each of the piston valves has a groove to leak the control oil in a corresponding one of the chambers to another one of the chambers that is adjacent to the corresponding chamber in an axis direction.