Closed-Cycle Turbomachine Startup and Rapid Deceleration
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Solution Overview
Problem
Closed-cycle turbomachines face challenges in starting and decelerating efficiently, particularly when using supercritical fluids, due to the need for expensive high-speed motors, complex systems, and potential fluid flow issues, which can lead to reliability concerns and increased costs.
Innovation Solution
A method involving charging a supercritical fluid to a starting mass greater than the design operating mass, heating it to achieve a supercritical state, and venting a discharge mass to initiate rotation, along with a deceleration process using heat exchangers to reduce fluid temperature and slow down the turbomachine, thereby managing fluid flow and reducing wear on bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a starter motor is used to drive the compressor to sustainable ignition speed, then the turbomachine can be started, but the system complexity and cost increase
Solution Approach 1:
The patent removes the starter motor from the system entirely. Instead of using a mechanical starter to drive the compressor, the system uses a valve to introduce high-pressure working fluid directly into the combustor, which ignites and drives the turbine-compressor rotor. This extraction of the starter motor eliminates the associated complexity while maintaining starting capability through a simpler pneumatic ignition system.
Solution Approach 2:
The patent replaces the mechanical starter motor system with a thermal-pneumatic system. Instead of using electrical power to mechanically drive the compressor, the system uses high-pressure working fluid introduction into the combustor to create thermal energy that drives the turbine, which in turn drives the compressor. This substitution eliminates mechanical/electrical starting components.
2Reliability
If a motor-driven compressor is used to create pressure rise for starting, then the closed-cycle turbomachine can be started, but the cost and complexity increase due to high-speed motor and high-pressure casing requirements
Solution Approach 1:
The patent removes the motor-driven compressor and high-pressure casing from the starting system. Instead of mechanically compressing the working fluid to high pressure, the system uses a valve to directly introduce pre-stored high-pressure working fluid from the environment or a storage system into the combustor. This extraction eliminates the need for motor-driven compression during startup.
Solution Approach 2:
The patent introduces a valve as an intermediary component that controls the direct introduction of high-pressure working fluid into the combustor. This valve acts as a mediator between the high-pressure fluid source and the combustor chamber, enabling starting without requiring a motor-driven compressor or complex high-pressure casing system.
3Reliability
If check valves are employed to prevent wrong direction flow during starting, then the turbomachine can start reliably, but the device complexity increases
Solution Approach 1:
The patent combines the flow control function into the main intake valve that introduces working fluid into the combustor. This single valve serves both as the primary fluid introduction mechanism and as the flow direction controller, eliminating the need for separate check valves. The valve's positioning and design inherently prevent wrong-direction flow while maintaining system simplicity.
4Duration of action of stationary object
If the turbomachine is rapidly decelerated during shutdown, then bearing life is extended, but the risk of bearing contact and wear increases at low speeds
Solution Approach 1:
The patent implements a multi-stage deceleration process with periodic adjustments. The valve introduction rate is initially high to rapidly reduce speed, then adjusted to a lower rate as the rotor approaches low speeds. This periodic modification of the deceleration rate allows the system to benefit from rapid deceleration while avoiding the harmful effects of bearing contact at very low speeds.
Solution Approach 2:
The system uses feedback from rotor speed sensors to dynamically adjust the valve introduction rate during shutdown. When the rotor speed is high, the valve introduces fluid at a higher rate for rapid deceleration. When the rotor speed approaches low speeds, the feedback signal triggers a reduction in valve introduction rate, preventing bearing contact and wear while still achieving bearing life extension through overall rapid deceleration.
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 allows for efficient starting and deceleration of closed-cycle turbomachines using supercritical fluids, reducing costs and complexity, improving reliability, and extending bearing life by controlling fluid flow and temperature.
Implementation Method 1
heating it to achieve a supercritical state
Implementation Method 2
at least one heat exchanger disposed along the closed cycle and configured to reduce a temperature of the supercritical fluid entering an inlet of the compressor
Data Source
AI summary
The present disclosure relates to methods for starting and rapidly decelerating a turbomachine in a power generation system that utilizes a supercritical fluid in a closed cycle.