Compressor/Expander Machine
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Solution Overview
Problem
The compressor/expander machine experiences damage when shut down, particularly at the high-pressure-side end faces of the screw rotor and the end wall surfaces of the machine housing, due to pressure differences and potential reversal of screw rotor direction or lubrication interruptions.
Innovation Solution
A method is implemented where an operation control unit reduces the speed of the motor/generator unit according to a predetermined speed curve until the screw rotor reaches a lowest speed range, preventing damage by maintaining a low speed that avoids abrasion, heating, or overheating at the sealing gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the compressor/expander machine is shut down immediately, then the shutdown process is quick and simple, but damage occurs to the screw rotor and end wall surfaces due to pressure differences and lubrication interruption
Solution Approach 1:
The control unit initiates a deceleration phase before complete shutdown, reducing the screw rotor speed to a predetermined minimum value. This preliminary action ensures that the sealing gap is maintained during the pressure equalization process, preventing damage to the screw rotor and end wall surfaces while still achieving a relatively quick shutdown.
2Reliability
If the screw rotor speed is reduced to a minimum value before shutdown, then damage to the sealing gap is prevented, but the shutdown process takes longer
Solution Approach 1:
The system dynamically adjusts the screw rotor speed during shutdown by implementing a deceleration phase that reduces speed to a predetermined minimum value rather than an immediate stop. This dynamic speed adjustment maintains the sealing gap integrity during pressure equalization while optimizing the shutdown duration through controlled deceleration.
3Loss of time
If the screw rotor speed is rapidly reduced, then the shutdown is faster, but abrasion and overheating occur in the sealing gap region
Solution Approach 1:
The control unit applies preliminary anti-action by implementing a controlled deceleration phase before shutdown, reducing the screw rotor speed to a predetermined minimum value. This prevents the harmful effects of rapid speed reduction that would cause abrasion and overheating in the sealing gap region, while still achieving a relatively fast shutdown through optimized deceleration rates.
Data Source
AI summary
In order to improve a method for operating a compressor/expander machine in a circuit for a working medium, wherein the compressor/expander machine has a machine housing with a screw rotor housing, in which at least one screw rotor arranged between a low-pressure side and a high-pressure side is arranged for compressing/expanding the working medium and is coupled to a motor/generator unit, in such a way that damage is avoided in the region of the screw rotors, it is proposed that an operation control unit is provided for operating the compressor/expander machine and, in the event of termination of operation of the compressor/expander machine, operates the motor/generator unit in accordance with a predetermined speed curve until a lowest speed range of the at least one screw rotor is reached, which prevents damage in the region of the screw rotor.