Steam Turbine Startup Sequence Optimization
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Solution Overview
Problem
The existing methods for starting a gas and steam turbine system are slow, requiring the gas turbine to be started and then waiting for steady-state conditions before directing steam to the steam turbine, which prolongs the startup process and increases thermal stresses on components.
Innovation Solution
Starting the steam turbine as early as possible with the first steam from the heat recovery steam generator, while continuously increasing steam pressure by selectively opening bypass stations, and maintaining a maximum load ramp for the gas turbine to reach base load quickly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gas turbine is started first and the steam turbine is started only after steady-state conditions are established in the steam system, then thermal stresses on thick-walled components are kept at a low level, but the starting process takes a long time
Solution Approach 1:
The steam turbine is started in advance before steady-state conditions are fully established in the steam system. The bypass stations are opened to allow steam to flow through the turbine while controlling the rate of pressure increase, enabling the turbine to start rotating before the steam system reaches steady state. This preliminary action reduces the overall starting time while still controlling thermal stresses through controlled load ramping.
Solution Approach 2:
The system transitions from a static waiting period for steady-state conditions to a dynamic process where the steam turbine is accelerated continuously as steam pressure increases. The load ramp is controlled dynamically based on the actual steam pressure and temperature conditions, allowing the turbine to start and accelerate in coordination with the steam system development rather than waiting for predetermined steady-state conditions.
2Productivity
If the gas turbine load is increased rapidly to reach base load quickly, then productivity is improved, but thermal stresses on steam turbine components increase
Solution Approach 1:
The control system continuously monitors steam pressure, temperature, and turbine load conditions to dynamically adjust the load ramp rate. The bypass station opening degree is adjusted based on feedback from pressure sensors and turbine performance measurements, allowing the system to optimize the balance between starting speed and thermal stress control in real-time rather than following a fixed predetermined schedule.
3Reliability
If bypass stations are kept open longer to control steam pressure during startup, then thermal stresses are reduced, but steam production efficiency decreases and power losses increase
Solution Approach 1:
The bypass stations remain open continuously during the entire startup process, allowing steam to flow through the turbine and perform useful work of accelerating the rotor from standstill to operating speed. This continuous useful action converts what would otherwise be wasted steam into productive turbine acceleration, reducing energy losses compared to traditional methods where steam is simply vented or condensed during startup.
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
This approach significantly reduces the startup time by approximately 50%, enhances operational flexibility, increases efficiency, and lowers investment costs by reducing the size of bypass stations, while minimizing thermal stresses and power losses.
Implementation Method 1
the working medium is fed to a heat recovery steam generator downstream of the gas turbine system on the exhaust gas side, in which heating surfaces are arranged in the form of tubes or tube bundles
Implementation Method 2
the waste heat of a gas turbine is expanded working medium is supplied to the steam system for generating steam
Implementation Method 3
the steam generated in the heat recovery steam generator is not initially fed to the turbine part of the steam turbine system, but is routed past the turbine via bypass stations
Implementation Method 4
fed directly to a condenser, which condenses the steam into water
Data Source
Figure 1a~1b
AI summary
The invention relates to a method for starting a gas and steam turbine system (1) which comprises a gas turbine system (Ia) which comprises at least one gas turbine (2), in addition to at least one steam turbine system (Ib) which comprises at least one steam turbine (20) and at least one steam system. Heat produced by the working fluid (AM) and which is released in the gas turbine (2) is guided to the steam system in order to produce steam which drives the steam turbine (20). According to the invention, during starting, the gas turbine (2) is started prior to the steam turbine (20) and the steam turbine (20) is started in the presence of the first steam in the system and is impinged upon by said steam.