Turbomachine Startup Control via Independent Steam Flow Modulation
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Solution Overview
Problem
Current steam turbine startup phase methods fail to consider multiple physical parameters, leading to reduced operational flexibility, increased mechanical component size, and decreased output due to unbalanced steam flow between high-pressure (HP) and intermediate-pressure (IP) sections, particularly during hot and cold starts.
Innovation Solution
A method that determines the Allowable Turbine Operating Space (ATOS) for each section, allowing unbalanced steam flow between the HP and IP sections by modulating valves based on real-time operational boundaries and physical parameters like thrust, rotor stress, and steam temperature, using a transfer function algorithm to control steam flow independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If steam flow is balanced between HP and IP sections during forward flow transfer, then steam flow control is simplified, but operational flexibility is reduced and mechanical component size increases
Solution Approach 1:
The patent segments the steam flow control by introducing separate control mechanisms for HP and IP sections. The mass flow ratio calculation allows independent adjustment of steam flow in each section based on their specific operational requirements, rather than enforcing a unified balanced flow approach. This segmentation enables tailored control strategies for each section, improving operational flexibility without excessive complexity.
2Force
If IP steam flow is increased prior to transfer, then axial thrust on IP section is reduced, but HP steam flow upon transfer becomes insufficient causing high exhaust temperature
Solution Approach 1:
The patent employs dynamic control of steam flow ratios between HP and IP sections based on real-time operational conditions. The mass flow ratio is not fixed but adjusted dynamically during the startup process, allowing the system to optimize axial thrust management in IP section while ensuring sufficient HP steam flow is available when transfer occurs, thereby preventing excessive exhaust temperatures.
Solution Approach 2:
The control method performs preliminary calculations of the optimal mass flow ratio before executing the forward flow transfer. By determining the appropriate steam flow distribution in advance based on predicted operational conditions, the system prepares the steam flow configuration that will achieve both adequate axial thrust support and sufficient HP section flow for temperature control during the actual transfer operation.
3Force
If IP steam flow is reduced prior to transfer, then axial thrust load is lessened, but HP steam flow upon transfer is lower than desired causing high exhaust temperature
Solution Approach 1:
The system dynamically adjusts the steam flow ratio between HP and IP sections based on real-time mass flow measurements and operational conditions. This dynamic control allows the system to find the optimal balance point where axial thrust load is minimized while ensuring sufficient HP steam flow is maintained to prevent excessive exhaust temperatures during the transfer process.
4Speed
If very high HP steam flow is used in cold starts, then startup speed is increased, but rotor stress becomes undesirable
Solution Approach 1:
The patent changes the control parameter from fixed high steam flow to a dynamically adjusted mass flow ratio between HP and IP sections. By calculating and controlling the ratio of steam flows based on operational conditions, the system can achieve adequate startup speed while distributing the mechanical load more favorably, thereby reducing rotor stress during cold start conditions.
Data Source
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AI summary
A method (400) for increasing the operational flexibility of a turbomachine during a startup phase is provided. The turbomachine may include a first section, a second section, and a rotor disposed within the first section and the second section. The method (400) may determine an allowable range of a physical parameter associated with the first section (440) and/or the second section (460). The method (400) may modulate a first valve (450) and/or a second valve (470) to allow steam flow into the first section and the second section respectively, wherein the modulation is based on the allowable range of the physical parameter. In addition, the physical parameter allows the method (400) to independently apportion steam flow between the first section and the second section of the turbomachine, during the startup phase.