NGL Stabilizer Side Stripper for Compressor Load Reduction
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Solution Overview
Problem
Conventional natural gas liquid (NGL) recovery units face challenges due to varying ambient conditions, leading to excessive condensation of ethane, propane, and butanes, which overwhelm traditional stabilizers and compressors, resulting in product loss and safety hazards, as well as increased capital costs for oversized compressors.
Innovation Solution
Implementing a side stripper and NGL recovery system in the stabilizer to capture and stabilize these condensables before they reach the NGL unit, utilizing a vapor side-draw to separate and recycle lighter hydrocarbons, reducing the compressor size and increasing plant capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional stabilizer without side stripper is used, then the structure is simpler, but the compressor becomes overwhelmed with condensables causing product loss and safety hazards
Solution Approach 1:
The stabilizer is segmented into multiple functional sections: a main stabilization column and a side stripper column. The side stripper specifically targets and removes light condensables (propane, butanes, i-pentane) from the feed stream before they enter the main stabilizer. This segmentation allows each column to perform its specialized function, preventing compressor overload while maintaining overall system reliability.
Solution Approach 2:
The side stripper acts as an intermediary component between the feed stream and the main stabilizer. It pre-treats the feed by removing problematic light components, thereby protecting the main stabilizer and downstream compressor from being overwhelmed. This intermediary function resolves the contradiction by adding a targeted intervention point without completely redesigning the entire system.
2Reliability
If the compressor is sized to handle full vapor load from stabilizer, then complete vapor handling capability is achieved, but capital costs increase dramatically
Solution Approach 1:
The side stripper performs preliminary removal of light condensables before the vapor reaches the compressor. By pre-stripping these components in a separate column, the vapor load on the compressor is significantly reduced. This allows the compressor to be sized for a smaller, more economical capacity while still maintaining adequate vapor handling capability for the reduced load.
Solution Approach 2:
The side stripper discards (removes) the problematic light condensables from the main vapor stream that would otherwise require compressor handling. These removed components are recovered as a separate product stream, reducing the burden on the compressor and lowering capital costs while maintaining reliable vapor handling for the remaining load.
3Productivity
If mechanical inlet feed chilling is applied, then more liquid condensation is produced increasing NGL recovery, but a larger and more expensive stabilizer overhead compressor is required
Solution Approach 1:
The system segments the condensation and stabilization process into two distinct stages: first, mechanical chilling produces condensed liquids; second, the side stripper specifically removes the light condensables generated by chilling. This segmentation allows the side stripper to handle the increased condensable load from chilling without requiring a proportionally larger main compressor, thus maintaining productivity while controlling device complexity.
Solution Approach 2:
The side stripper serves as an intermediary that manages the increased condensable load resulting from mechanical inlet feed chilling. It intercepts and removes the additional light components before they can overwhelm the main stabilizer and compressor system, enabling the chilling process to operate at higher capacity without linearly increasing compressor requirements.
4Productivity
If a side stripper is added to the stabilizer, then compressor size is reduced and plant capacity increases, but the device complexity increases
Solution Approach 1:
The stabilizer system is divided into functionally distinct segments: the side stripper column for light component removal and the main stabilizer column for overall stabilization. This segmentation enables each unit to be optimized for its specific function, increasing overall plant capacity through specialized performance rather than requiring a single oversized complex unit.
Solution Approach 2:
The side stripper, while adding a component, provides multiple functions: it removes light condensables, pre-treats the feed stream, protects the main stabilizer, and reduces compressor load. This multi-functionality justifies the added device complexity by delivering several benefits simultaneously, thereby increasing effective plant capacity through efficient resource utilization.
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 minimizes recompression requirements, reduces capital costs, enhances safety by stabilizing gasoline before storage, and increases NGL recovery efficiency, thereby reducing VOC emissions and operational hazards.
Implementation Method 1
removing a portion of the stream from a middle section of the column and sending the portion to a side stripper to separate the middle portion into a light hydrocarbon vapor portion and a natural gas liquid product
Implementation Method 2
separate the middle portion into a light hydrocarbon vapor portion and a natural gas liquid product
Implementation Method 3
removing a second portion of the stream from a bottom section of the column and sending the second portion to a stabilizer reboiler to separate the second portion into a stabilized gasoline product and a lighter hydrocarbon vapor portion to be returned to the column
Data Source
AI summary
The invention provides a process and system for processing natural gas and separating natural gas liquids into natural gasoline and a Y-grade liquid that meets specifications for low methane and ethane content. The process and system includes a side stripper and reboiler to separate methane and ethane from heavier hydrocarbons and a reboiler system to stabilize the natural gasoline.