Centrifugal Gas Compressor Surge Control Using Liquid Buffer Injection
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Solution Overview
Problem
Centrifugal gas compressors are sensitive to dynamic fluctuations in gas density, particularly when handling PSA tail gas with varying composition and molecular weight, leading to operational instability and flow disturbances in downstream processes.
Innovation Solution
A secondary anti-surge control loop is implemented, using a liquid product stored in a tank on level control to inject gas into the compressor suction, thereby damping gas density fluctuations and reducing the load on the primary anti-surge system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a primary anti-surge system using discharge gas recycle is used to protect the compressor from surges, then the compressor is protected from surge conditions, but flow disturbances are introduced into downstream operations
Solution Approach 1:
The patent introduces a buffer gas stream as an intermediary substance that mixes with the feed stream upstream of the compressor. This buffer gas acts as a mediator to dampen gas density fluctuations and prevent surge conditions without requiring recycle of discharge gas, thereby protecting the compressor while avoiding flow disturbances to downstream operations
Solution Approach 2:
The patent extracts the anti-surge function from the discharge gas recycle loop and implements it separately through buffer gas injection upstream of the compressor. This separation allows surge protection to be achieved independently, eliminating the harmful flow disturbances that would otherwise be introduced into downstream operations by discharge gas recycle
2Stability of the object's composition
If buffer gas is injected into the compressor suction to dampen gas density fluctuations, then gas density stability is improved, but additional equipment and complexity are required
Solution Approach 1:
The buffer gas system serves multiple functions: it dampens gas density fluctuations to prevent compressor surge, provides a stable gas source for the compressor, and can be integrated with existing process streams. This multi-functionality achieves gas density stabilization without proportionally increasing system 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
This solution enhances the operational reliability and robustness of centrifugal gas compressors by mitigating gas density fluctuations and minimizing flow disturbances to downstream operations, while also reducing the need for large buffer material volumes.
Implementation Method 1
the storage vessel comprises a liquid buffer material, and the buffer stream comprises a gaseous phase of the liquid buffer material
Implementation Method 2
increasing a pressure of the feed stream and the buffer stream in the compressor to provide a high-pressure gas stream
Data Source
AI summary
Processes and apparatuses for operating a centrifugal gas compressor. A storage tank containing a liquid buffer material is provided and used to offset density fluctuations in the gas stream passed to the compressor. The storage tank may contain a component of the high-pressure gas stream provided by the compressor, such as carbon dioxide.