Compressor Recycle and Throttling Control to Prevent Surge
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Solution Overview
Problem
Existing methods for liquefying natural gas face challenges due to the presence of heavier hydrocarbons and impurities, which can cause compressor damage through surge and choking, leading to vibration, noise, and mechanical issues.
Innovation Solution
A method and apparatus for controlling compressors by measuring pressure and flow values to automatically control throttling valves and recycle lines, preventing surge and choking by regulating pressure and flow, thereby ensuring safe operation within acceptable operating windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a surge control system is used to prevent compressor damage, then compressor reliability is improved, but the system complexity increases due to additional sensors, control algorithms, and differential pressure measurements
Solution Approach 1:
The patent implements feedback control by continuously monitoring compressor operating parameters (flow rate, pressure, temperature) and automatically adjusting the recycle valve position to maintain operation within the safe operating envelope. The control system uses real-time feedback from sensors to prevent surge and choking conditions, replacing complex differential pressure calculations with direct parameter monitoring and automatic valve adjustment.
2Productivity
If heavier hydrocarbons and impurities are removed from natural gas before liquefaction, then liquefaction efficiency is improved, but the NGL recovery process becomes more complex requiring additional separation columns and fractionation units
Solution Approach 1:
The patent applies preliminary action by implementing compressor control measures before the liquefaction process to prevent surge and choking caused by heavier hydrocarbons. By controlling compressor operation within safe parameters and managing flow rates appropriately, the system prevents operational issues that would otherwise require complex upstream separation processes, allowing direct liquefaction of raw natural gas including NGL components.
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
The solution effectively reduces the likelihood of compressor damage by preventing surge and choking, allowing for efficient processing of hydrocarbon streams and efficient liquefaction of natural gas.
Implementation Method 1
passing the or each first compressed stream through at least one throttling valve downstream of the compressor recycle line to provide a controlled stream
Implementation Method 2
passing the compressor feed stream through the one or more first compressors, the or each first compressor having a first inlet and a first outlet to provide one or more first compressed streams
Data Source
AI summary
Method and apparatus for controlling one or more first compressors (12), through which a compressor feed stream (10) is passed. At least one throttling valve (32) is provided downstream of a compressor recycle line (22), which is provided around the or each first compressor (12) and includes an in-line first recycle valve (24). Sometimes, at least a fraction of the compressor feed stream (10) is selectively allowed to bypass the or each first compressor (12) and the at least one throttling valve, via a bypass line (60). At least one of the throttling valves (32) is automatically controlled using the measurement values of at least one pressure and at least one flow of the group consisting of: the pressure (P1) of the compressor feed stream (10), the flow (F1) of the compressor feed stream (10), the pressure (P2) of the first compressed stream (20) and the flow (F2) of the first compressed stream (20). A first compressor controlled this way may be used in a method of cooling an initial hydrocarbon stream (100).