Multiple reflux stream hydrocarbon recovery process
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Solution Overview
Problem
Existing cryogenic processes for recovering ethane and heavier hydrocarbon components from gas streams are limited by the maximum recovery achievable with current reflux stream configurations, and there is a need for processes that can efficiently transition between high throughput and high recovery modes while minimizing operating and capital costs.
Innovation Solution
A system and method that allows flexible operation by splitting the inlet gas stream into multiple feed streams, using different reflux streams (residue gas or feed gas) to a demethanizer tower, and controlling valves to switch between high throughput and high ethane recovery modes, utilizing heat exchangers and compressors to optimize recovery and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single tower with reflux stream from hydrocarbon gas feed stream is used, then the process is simple to operate, but the maximum recovery of ethane is limited
Solution Approach 1:
The single tower is segmented into multiple towers (demethanizer, deethanizer, depropanizer) with intermediate condensers and reboilers, creating a multi-stage separation system that achieves higher ethane recovery while maintaining operational simplicity through standardized modular units
Solution Approach 2:
Intermediate condensers and reboilers are introduced as intermediary components between towers, enabling heat exchange and material transfer that enhances separation efficiency and ethane recovery without significantly complicating the overall process operation
2Quantity of substance
If multiple towers with intermediate condensers and reboilers are used, then ethane recovery is increased, but the process complexity increases
Solution Approach 1:
Multiple towers, condensers, and reboilers are merged into an integrated system where heat and material streams are systematically exchanged between units, achieving high ethane recovery while the unified design reduces operational complexity compared to independent units
Solution Approach 2:
Intermediate condensers and reboilers serve multiple functions: they act as heat exchangers between streams, provide separation stages, and enable flexible operation modes (high throughput vs. high recovery), reducing the need for additional specialized equipment
3Quantity of substance
If residue gas is recycled as reflux stream, then ethane recovery is improved, but the throughput is reduced
Solution Approach 1:
The reflux stream configuration is made dynamic and adjustable, allowing operators to switch between high recovery mode (residue gas recycle) and high throughput mode (fresh feed gas reflux), enabling the system to adapt to varying market demands and operational conditions
4Productivity
If fresh feed gas is used as reflux stream, then throughput is increased, but ethane recovery decreases
Solution Approach 1:
The system provides dynamic operability to switch between reflux configurations, allowing operators to select fresh feed gas as reflux when high throughput is prioritized, while maintaining the option to switch to residue gas recycle when maximum ethane recovery is the goal
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
Enables efficient recovery of ethane and heavier hydrocarbons with flexibility to switch between high throughput and high recovery modes, increasing ethane recovery from 92% to 97% while allowing a 20% increase in throughput, thus optimizing operational efficiency and profitability.
Implementation Method 1
A first heat exchanger may be provided for cooling the first feed stream, and a second heat exchanger may be provided for cooling the second feed stream
Implementation Method 2
A separator for separating the cooled first and second feed streams into a first vapor stream and a first liquid stream
Implementation Method 3
The demethanizer tower may separate the feed streams into a demethanizer overheads stream and a demethanizer bottoms stream
Implementation Method 4
One or more compressors may be provided for compressing the demethanizer overheads stream to form a residue gas stream
Data Source
AI summary
Systems herein separate an inlet gas stream containing methane, C2 components, C3 components and optionally heavier hydrocarbons into a volatile gas fraction containing methane and a less volatile hydrocarbon fraction containing C2+ components. The system may include piping, valving, and controls configured to flexibly allow the system to operate in a high ethane recovery mode, a high throughput mode, or in some embodiments, a high propane recovery mode.