Integrated Compressor-Expander for CAES Systems
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Solution Overview
Problem
Compressed air energy storage (CAES) power generation devices have a large size and high cost due to the separate configuration of compressors and expanders, which increases maintenance and installation costs.
Innovation Solution
Integration of a compressor/expander combined machine with a motor/generator combined machine and a pressure accumulator, utilizing a lubricant labyrinth seal and air ring seals to maintain sealing without depending on rotation direction, and mechanical check valves for airflow direction switching, along with a heat exchange system for thermal energy storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a compressor and an expander are separately configured, then the device can perform compression and expansion functions, but the entire device is increased in size and cost
Solution Approach 1:
The patent combines the compressor and expander into a single integrated machine with a unified casing, rotating shaft, and sealing system. This merging eliminates the need for separate compression and expansion devices, directly reducing overall device size and cost while maintaining both functional capabilities through bidirectional operation of the same mechanical components
Solution Approach 2:
The integrated compressor/expander machine is designed to perform both compression and expansion functions using the same hardware components. The rotating shaft member and sealing structures operate bidirectionally, allowing the single device to universally handle both air compression during energy storage and air expansion during power generation, eliminating the need for separate dedicated devices
2Ease of repair
If separate compressors and expanders are used, then the functions are well-defined, but the number of parts to be maintained increases
Solution Approach 1:
By merging the compressor and expander into one integrated unit with shared components including the casing, rotating shaft, bearings, and sealing systems, the patent reduces the total number of parts that require maintenance. The unified design means fewer independent systems to monitor, service, and repair, directly improving ease of repair while reducing maintenance costs
3Ease of manufacture
If separate compressors and expanders are used, then each component can be optimized independently, but piping construction cost increases
Solution Approach 1:
The integrated compressor/expander design eliminates the need for complex piping systems that would be required to connect separate compression and expansion devices. The unified machine has internal flow paths and a single external connection point, dramatically simplifying piping construction and reducing associated costs while maintaining full functional capability
4Reliability
If a lubricant labyrinth seal is used in a bidirectional rotating shaft, then sealing is achieved without rotation direction dependence, but the seal structure must be rotationally axisymmetric
Solution Approach 1:
The patent employs a lubricant labyrinth seal with rotationally axisymmetric geometry that functions equally well in both clockwise and counter-clockwise rotation directions. This axisymmetric design ensures consistent sealing performance regardless of rotation direction, achieving reliable sealing for bidirectional operation without requiring complex directional-dependent structures
Solution Approach 2:
The lubricant labyrinth seal acts as an intermediary sealing mechanism that uses a labyrinthine path and lubricant film to prevent gas leakage. This intermediate sealing approach effectively handles bidirectional rotation by creating a rotation-direction-independent barrier, achieving reliable sealing through the mediating effect of the lubricant and labyrinth structure
Data Source
AI summary
A CAES power generation device includes: a compressor/expander combined machine that is of displacement type and has a function as a compressor for compressing air and a function as an expander for expanding compressed air; a motor/generator combined machine that is mechanically connected to the compressor/expander combined machine and has a function as an electric motor for driving the compressor/expander combined machine and a function as a generator driven by the compressor/expander combined machine; and a pressure accumulation tank that is fluidly connected to the compressor/expander combined machine and stores compressed air generated by the compressor/expander combined machine.