Multistage Cryogenic Expander With Variable Nozzle Geometry
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Solution Overview
Problem
Existing gas liquefaction processes face inefficiencies due to high energy consumption and the limitations of Joule-Thomson valves for cryogenic fluid expansion, particularly in reducing the temperature of liquefied gases like propane and methane, which requires significant energy input and is not commercially viable at lower temperatures.
Innovation Solution
A multistage expander with hydraulic stages having different physical geometries for nozzle vanes and a double wound stator with adjustable windings to optimize performance across varying operating conditions, allowing for efficient energy extraction and conversion from high-pressure cryogenic fluids into kinetic and electrical energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a Joule-Thomson valve is used for gas expansion, then the expansion process is simple, but the energy consumption is high and efficiency is low
Solution Approach 1:
The patent replaces the Joule-Thomson valve (a passive throttling device) with an expander machine that uses mechanical expansion to perform work. The expander converts the expansion energy of the gas into mechanical work, which is then converted to electrical energy, thereby utilizing the expansion energy instead of dissipating it, thus solving the high energy consumption problem while maintaining process simplicity
Solution Approach 2:
The expander system uses the expansion energy of the gas itself to drive the expansion process and generate electricity, making the system self-sufficient in energy terms. The gas expansion directly powers the expander, which in turn provides cooling for the liquefaction process, creating a self-service energy cycle that eliminates the need for external energy input
2Device complexity
If a single geometry nozzle vane is used in all hydraulic stages, then the device structure is simple, but the performance cannot be optimized for varying operating conditions
Solution Approach 1:
The patent applies different nozzle vane geometries to different hydraulic stages based on the local operating conditions. Each stage is designed with specific nozzle geometry optimized for its pressure and flow characteristics, allowing the system to maintain high efficiency across varying operating conditions while managing complexity through systematic design
Solution Approach 2:
The system incorporates the ability to change nozzle vane configurations dynamically or semi-dynamically. By equipping the expander with multiple nozzle vane sets that can be swapped or adjusted, the system adapts to varying operating conditions, transforming a static single-geometry design into a dynamic multi-geometry system that optimizes performance
3Device complexity
If the generator operates at fixed windings, then the structure is simple, but the efficiency drops significantly at loads below 100%
Solution Approach 1:
The patent designs the generator with dual windings that can operate in different configurations. The same generator structure can handle both 100% load conditions (using one winding) and 50% load conditions (using the other winding), making the generator universally applicable across different load requirements without sacrificing efficiency, thus solving the energy loss problem while controlling structural complexity
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
The solution enables efficient reduction of enthalpy and temperature of cryogenic fluids, achieving 80-90% of ideal energy reduction, independent of Carnot efficiency, and maintains peak efficiency across a wide range of loads by dynamically adjusting windings and nozzle geometries, thus improving the overall efficiency and reliability of gas liquefaction processes.
Implementation Method 1
The solution enables efficient reduction of enthalpy and temperature of cryogenic fluids, achieving 80-90% of ideal energy reduction
Implementation Method 2
In 1902 the French engineer George Claude developed a piston expansion engine to replace the Joule-Thomson valve to extract mechanical work from the gas expansion process
Implementation Method 3
an expander is equipped with a generator having a double wound stator with two sets of parallel windings
Implementation Method 4
The cryogenic liquid expander directly extracts the heat energy from the liquefied gas by expanding the liquid from a high pressure level to a low pressure level
Data Source
AI summary
Embodiments are directed to an expander having two or more hydraulic stages with different physical geometries. In an embodiment, a first hydraulic stage uses nozzle vanes machined with a first geometry, while a second hydraulic stage uses nozzle vanes machined with a second geometry. Different nozzle vanes can be combined to tune the performance of the expander as the optimal operating conditions change. In yet another embodiment, an expander is equipped with a generator having a double wound stator with two sets of parallel windings. For high operating loads greater than a threshold, a first set of windings operates while a second set of windings, operating at a lower frequency, is disconnected. For operating loads that are less than the threshold, the first set of windings is disconnected and the second set of windings operates, enabling the generator to continue to operate close to 100% load for less expander power.