Centrifugal Compressor Low-Power Operation for Dry Gas Seal Protection
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Solution Overview
Problem
Centrifugal compressors operating with gas produced from renewable energy sources face frequent shutdowns and startups due to variable energy availability, leading to increased wear of dry gas seals, reduced compressor lifetime, and higher maintenance costs, as well as operational risks from frequent start-ups and potential corrosion.
Innovation Solution
Implementing a process that switches centrifugal compressors between normal power mode and low power mode based on gas flow rates, using renewable energy supplemented by other sources when necessary, to maintain seal separation and reduce wear, while conserving electricity for other process uses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If centrifugal compressors are operated at fixed maximum speed to maximize gas compression output, then productivity is improved, but the dry gas seal wear increases and reliability deteriorates due to frequent shutdowns and restarts
Solution Approach 1:
The patent applies dynamics by transitioning from fixed maximum speed operation to variable speed operation. The compressor speed is dynamically adjusted based on gas flow availability - operating at maximum speed when gas flow is sufficient, and reducing to a minimum speed when gas flow is limited. This dynamic speed adjustment prevents frequent shutdowns and restarts, thereby extending compressor lifetime while maintaining maximum productivity when conditions permit.
Solution Approach 2:
The patent changes the operational parameter of compressor speed from a fixed maximum value to a variable parameter. By adjusting the speed parameter between maximum and minimum levels based on gas flow conditions, the system resolves the contradiction between maintaining high productivity and ensuring reliability. The speed parameter is modified in response to changing operational conditions to optimize both objectives.
2Use of energy by moving object
If centrifugal compressors are frequently shut down during periods of insufficient gas flow, then energy consumption is reduced, but wear on dry gas seals increases and reliability deteriorates
Solution Approach 1:
The patent applies dynamics by implementing dynamic speed adjustment rather than binary on/off operation. When gas flow is insufficient, the compressor transitions to a minimum speed mode rather than shutting down completely. This dynamic approach maintains seal face separation through continued rotation at low speed, preventing wear while consuming minimal energy. The system adapts its operational state continuously based on gas flow availability.
Solution Approach 2:
The patent applies preliminary action by maintaining a minimum rotational speed before complete shutdown would occur. This preliminary low-speed operation ensures that seal faces remain separated and lubricated even during periods of insufficient gas flow, preventing the harmful effects of frequent start-stop cycles. The minimum speed acts as a protective measure that preserves seal lifetime while managing energy consumption.
3Use of energy by moving object
If centrifugal compressors are operated at variable speeds to match gas flow availability, then energy efficiency is improved, but maintaining seal face separation becomes difficult
Solution Approach 1:
The patent applies parameter changes by establishing specific speed thresholds for operational modes. The compressor operates at maximum speed when gas flow is sufficient, and transitions to a defined minimum speed when gas flow is limited. This parameter-based control ensures that the speed remains high enough to maintain seal face separation through centrifugal forces while minimizing energy consumption during low-flow periods.
Solution Approach 2:
The patent applies copying by maintaining the essential function of seal face separation through copied operational characteristics. Even at minimum speed, the compressor replicates the critical condition of seal face separation that occurs at maximum speed, ensuring reliability is maintained. The minimum speed mode copies the protective effect of high-speed operation regarding seal lubrication and separation.
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 extends the lifetime of dry gas seals, reduces maintenance costs, and minimizes operational risks by maintaining seal separation and optimizing power usage, even with variable renewable energy inputs.
Implementation Method 1
Gas typically enters at the center of the impellers and is propelled out to the radial edges under rotary motion to deliver gases at high velocity
Implementation Method 2
The opposed seal faces of the dry gas seals are quickly separated and maintained apart as the motor speed of the compressor is maintained at a high level
Data Source
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AI summary
Operation of a multistage compression system (20) comprising at least one centrifugal compressor (6) having a dry gas seal with opposed seal faces, for compressing a gas feed having a variable flow rate is improved by operating the or at least one centrifugal compressor (6) in a low power mode where the opposed faces of the dry gas seal are not in contact during periods when gas flow through the centrifugal compressor(s) (6) is not sufficient for normal operation. Such operation not only reduces damage to the dry gas seals and hence improves reliability, but also reduces the overall power requirement of the overall compression system (20).