Steam Turbine Preheating Storage for Faster Carnot Battery Startup
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Solution Overview
Problem
Existing systems for repurposing coal-fired power plants into Carnot batteries lack responsiveness for rapid startup and electricity production, as they require maintaining stable steam parameters and load on an operating turbine, which is not compatible with grid requirements.
Innovation Solution
A thermal management system is introduced with an additional thermal storage unit fluidly connected to the steam cycle, allowing for preheating and temperature maintenance of the turbine and steam cycle components using thermal energy stored in the Carnot battery, independent of the Carnot battery's thermal storage system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a steam turbine from a coal-fired power plant is reused in a Carnot battery, then the system can generate electricity during peak demand periods, but the turbine startup time is too long (hours) to meet grid responsiveness requirements
Solution Approach 1:
The patent applies preliminary action by preheating the turbine and steam cycle components using thermal energy stored in the additional thermal storage unit before electricity generation is needed. This preheating process occurs during periods of low electricity demand when the Carnot battery stores thermal energy, allowing the turbine to start up quickly (in under 2 hours) when peak demand occurs, thus resolving the contradiction between reliability and startup time.
2Speed
If steam parameters are maintained stable on an operating turbine for preheating, then quick startup is enabled, but operational constraints prevent compatibility with grid requirements for load variability
Solution Approach 1:
The patent segments the thermal storage function into two independent systems: the Carnot battery's thermal storage module for bulk energy storage, and an additional thermal storage unit specifically dedicated to turbine preheating and temperature maintenance. This segmentation allows the preheating system to operate independently, enabling quick startup without requiring the Carnot battery to maintain stable load, thus resolving the contradiction between startup speed and grid adaptability.
Solution Approach 2:
The additional thermal storage unit acts as an intermediary between the Carnot battery and the turbine. It receives thermal energy from the Carnot battery during charging periods and releases it during preheating, decoupling the turbine operation from direct Carnot battery control. This intermediary enables the turbine to respond quickly to grid demands without being constrained by the need to maintain stable steam parameters from the Carnot battery operation.
3Loss of time
If the Carnot battery operates continuously to maintain thermal energy for quick startup, then responsiveness is improved, but fossil fuel backup systems must be used during low demand periods, increasing carbon footprint
Solution Approach 1:
The system applies self-service by using excess renewable electricity from the grid during low-demand periods to charge the Carnot battery's thermal storage module. This stored thermal energy then serves the dual purpose of enabling quick turbine startup and maintaining operational readiness without requiring continuous Carnot battery operation or fossil fuel backup. The system essentially services its own preheating needs using stored renewable energy, eliminating the need for fossil fuel intervention.
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 faster steam production and turbine startup without operating the Carnot battery, utilizing low or surplus renewable electricity, and avoiding fossil fuel use, thus enhancing system responsiveness and reducing startup time from hours to under 2 hours.
Implementation Method 1
an additional thermal storage unit fluidly connected to the steam cycle and intended for storing steam from the steam cycle, separate from the thermal storage module of the Carnot battery
Implementation Method 2
a pair of preheating fluid connections including a steam turbine feed fluid connection arranged between the thermal storage device and the steam cycle upstream of the turbine to ensure the fluid connection from the thermal storage device to the steam cycle so as to provide preheating
Implementation Method 3
a heat-to-electricity conversion module including a steam cycle and a turbine arranged on the steam cycle to expand the steam for electricity production
Implementation Method 4
an electricity-to-heat conversion module, a thermal storage module for the heat produced by the electricity-to-heat conversion module
Data Source
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AI summary
The invention relates to a system comprising a Carnot battery comprising a module for transforming electricity into heat, a module for thermal storage of the produced heat and a module for transforming the heat, the module for transforming the destored heat comprising a steam cycle and a turbine arranged on the steam cycle. The system comprises an additional thermal storage unit fluidically connected to the steam cycle and intended for storing steam from the steam cycle and separate from the thermal storage module of the Carnot battery, the additional thermal storage unit comprising - a thermal storage device, - a fluid connection for supplying steam to the turbine and a return fluid connection, - a load fluid connection and a discharge fluid connection.