Integrated expander and motor-compressor assembly and closed loop cooling circuit comprising such an assembly
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Solution Overview
Problem
Existing expander and motor-compressor assemblies face issues with shaft dynamic behavior degradation and component damage due to cooled expanded gas migration when the flexible coupling device fails, leading to mechanical power loss and overspeed risks.
Innovation Solution
The integrated expander and motor-compressor assembly features a flexible coupling device connecting two transmission shafts with radial and thrust bearings, a gas diffuser to direct gas away from sensitive components, and a closed loop cooling circuit with heat exchangers to manage gas pressure and temperature, ensuring continued operation and protection of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the expander and compressor are mounted on a common shaft, then the device complexity is reduced, but the dynamic behavior of the shaft is degraded
Solution Approach 1:
The system divides the shaft into two separate transmission shafts (first transmission shaft for motor, second transmission shaft for expander and compressor) connected by a flexible coupling device. This segmentation allows each shaft to be optimized independently for its specific components, improving dynamic behavior while maintaining a relatively simple overall structure.
2Device complexity
If the flexible coupling device breaks down, then the device complexity is reduced, but the cooled expanded gas migrates to and damages the bearings and motor
Solution Approach 1:
The gas diffuser is pre-positioned between the expander and the first radial bearing to create a protective barrier. This preliminary protective structure ensures that even if the flexible coupling fails, the cooled expanded gas cannot directly reach and damage the bearings and motor, as the diffuser deflects the gas flow away from these sensitive components.
3Force
If axial thrust bearings are added to compensate for differential pressure, then the thrust compensation is improved, but the shaft length increases and dynamic behavior is degraded
Solution Approach 1:
The system combines the thrust compensation function with the existing radial bearing structure by positioning the radial bearings to also handle axial thrust loads. This merging of functions eliminates the need for separate axial thrust bearings, maintaining compact shaft length while still compensating for differential pressure forces acting on the compressor wheels.
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 configuration maintains operational efficiency by preventing cooled expanded gas from damaging components and reduces shaft length, enhancing dynamic behavior and eliminating the need for overspeed control systems.
Implementation Method 1
a gas diffuser between the expander and a first radial bearing of the second transmission shaft, the first bearing being the closest bearing to the expander... The gas diffuser is configured to diffuse gas directed to the expander and to the first radial bearing
Implementation Method 2
a flexible coupling device connecting the transmission shafts... the power generated by the gas expanded in the expander is partly recovered as compression work by the compressor. The electric motor supplies the compressor with additional mechanical power
Implementation Method 3
A first heat exchanger of the at least three heat exchangers is coupled with a gas outlet of the low pressure part and a gas inlet of the high pressure part... The first and second heat exchangers are configured to cool the gas flowing through the first and second heat exchangers
Implementation Method 4
at least two transmission shafts, each supported in the housing by at least two radial bearings... Each shaft is supported by two radial bearings, for example magnetic bearings
Implementation Method 5
an electric motor mounted on a first transmission shaft... The electric motor supplies the compressor with additional mechanical power
Implementation Method 6
an expander positioned in a cantilever configuration on the second transmission shaft... the power generated by the gas expanded in the expander is partly recovered as compression work by the compressor
Data Source
Figure 1
Figure 2
AI summary
The integrated expander and motor-compressor assembly (2) comprises a compression section (9) mounted between the two radial bearings (15, 16) on a transmission shaft (10), an expander (30) cantilevered at a free end of the transmission shaft, a gas diffuser (33) and a duct (34) between the expander and a first radial bearing (16), the first radial bearing been the closest radial bearing to the expander. The gas diffuser diffuses a gas barrier which is sucked up by the duct.