Trip Throttle Valve Isolation for Online Turbine Protection Testing
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Solution Overview
Problem
Steam turbine trip throttle valves often malfunction due to infrequent testing, leading to unsafe shutdowns during emergency conditions, as traditional testing methods require the turbine to be taken offline, leaving it unprotected during the process.
Innovation Solution
A trip throttle valve system with a hydraulic actuator assembly and parallel flow paths, allowing for testing during operation while maintaining the ability to safely shut down the turbine in case of a trip condition, using isolation valves to isolate components for testing without disrupting the turbine's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the steam turbine is tripped to test the trip throttle valve, then the valve can be tested, but the turbine must be taken offline resulting in production and economic losses
Solution Approach 1:
The trip throttle valve is divided into two independent throttling paths: a first throttling path with a first trip throttle valve and a second throttling path with a second trip throttle valve. This segmentation allows one valve to be tested while the other remains operational, eliminating the need to take the turbine offline for testing.
Solution Approach 2:
The system changes the operational state of the trip throttle valves between normal operation mode (both valves open) and testing mode (one valve isolated using lockout devices). This parameter change enables testing without complete shutdown by transitioning between different operational configurations.
2Productivity
If lockout devices are used to isolate trip components for testing, then the turbine can remain online, but the turbine becomes unprotected from potential trip conditions during testing
Solution Approach 1:
By segmenting the trip throttle valve into two independent paths with separate lockout devices, the system ensures that isolating one path for testing does not compromise the protection capability of the other path. The turbine remains protected by the non-tested valve during the testing of the other valve.
Solution Approach 2:
The system prepares backup protection capability in advance by having two redundant trip throttle valves. When one valve is isolated for testing, the other valve is already in place to provide protection, cushioning against the loss of protection capability during testing.
3Productivity
If the trip throttle valve is not tested regularly, then the turbine remains operational, but scale or rust accumulates affecting the valve's ability to close properly
Solution Approach 1:
The dual-valve configuration enables continuous operation of the turbine while maintaining continuous testing capability. One valve can be tested periodically without interrupting the protective function provided by the other valve, ensuring ongoing reliability through continuous testing action.
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
Enables the testing of trip throttle valves during normal operation, ensuring the turbine remains protected and operational, avoiding production losses and ensuring safe emergency shutdowns.
Implementation Method 1
a biasing member disposed about the valve stem and configured to bias the piston in a first position such that the valve head is seated in the valve seat
Implementation Method 2
a hydraulic cylinder configured to receive the piston and a hydraulic fluid therein, and an actuator assembly fluidly coupled with the hydraulic cylinder. The actuator assembly may be configured to transfer the hydraulic fluid to and from the hydraulic cylinder via a pressure differential across the piston
Implementation Method 3
The trip valve assembly may include a plurality of trip valves fluidly coupled to the hydraulic cylinder via a first flow path and a second flow path. The first flow path and the second flow path may be in parallel with one another
Data Source
AI summary
Systems and methods for protecting a turbomachine may include a trip throttle valve having a throttle valve assembly and a trip valve assembly. The trip valve assembly may include a plurality of trip valves fluidly coupled to a hydraulic cylinder of the throttle valve assembly via a first flow path and a second flow path in parallel with one another. The trip valve assembly may also include a plurality of isolation valves fluidly coupled to the hydraulic cylinder via the first flow path and the second flow path. The plurality of isolation valves may be configured to selectively prevent fluid communication between the plurality of trip valves and the hydraulic cylinder to allow testing of one or more of the plurality of trip valves during operation of the turbomachine.