CO2 Power Plant Startup Using Oxidant Bypass Ignition
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Solution Overview
Problem
Power production plants face challenges in efficiently starting up operations due to limitations in turbine speed, which restricts combustor ignition until a certain threshold is reached, preventing efficient transition from idle to full operational mode.
Innovation Solution
A power production system configuration that includes a bypass line for passing compressed oxidant to the recycle flow line, allowing combustor ignition below the turbine threshold speed, utilizing a motor-driven oxidant compressor to provide necessary flow volume and pressure, and a recuperative heat exchanger to manage temperature and flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the system waits for the turbine to reach threshold speed before combustor ignition, then the turbine can operate at stable speed, but the startup time is extended and the transition from idle to full operational mode is inefficient
Solution Approach 1:
The oxidant compressor is activated before the turbine reaches threshold speed to pre-compress and deliver oxidant to the combustor. This preliminary action enables combustor ignition to occur below the turbine threshold speed, eliminating the waiting period and extending the operational range during startup while maintaining system reliability through controlled oxidant delivery.
2Productivity
If the turbine threshold speed is reduced to allow earlier combustor ignition, then startup efficiency improves, but the turbine may not achieve stable operation
Solution Approach 1:
The oxidant compressor serves as an intermediary device that decouples the combustor ignition condition from the turbine speed threshold. By providing independently controlled oxidant compression and delivery, it enables ignition at lower turbine speeds without compromising the stability requirements, thus resolving the contradiction between startup speed and operational stability.
3Productivity
If a bypass line is added to pass compressed oxidant to the recycle flow line, then combustor ignition below threshold speed is enabled, but the system complexity increases
Solution Approach 1:
The bypass line with the oxidant compressor is designed to serve multiple functions: enabling combustor ignition below threshold speed, providing continuous oxidant delivery during transition, and maintaining flexibility for different operational scenarios. This multi-functionality justifies the added complexity by delivering operational benefits across multiple phases of plant operation.
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 efficient startup and transition to normal operating conditions by allowing combustor ignition below the turbine threshold speed, ensuring continuous flow regulation and minimizing differences in combustion chemistry during startup, thus facilitating a smoother transition to full operational mode.
Implementation Method 1
a recuperative heat exchanger to manage temperature and flow
Implementation Method 2
a motor-driven oxidant compressor to provide necessary flow volume and pressure
Implementation Method 3
combustor ignition below the turbine threshold speed
Data Source
AI summary
The present disclosure relates to systems and methods that provide power generation using predominantly CO2 as a working fluid. In particular, the present disclosure provides for particular configurations for startup of a power generation system whereby the combustor may be ignited before the turbine is functioning at a sufficiently high speed to drive the compressor on a common shaft to conditions whereby a recycle CO2 stream may be provided to the combustor at a sufficient flow volume and flow pressure. In some embodiments, a bypass line may be utilized to provide additional oxidant in place of the recycle CO2 stream.