Compact Hydrocarbon Gas Processing Assembly for C2 and C3 Recovery
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Solution Overview
Problem
Conventional cryogenic expansion processes for natural gas liquids recovery are inefficient in recovering C2 and C3 components due to lack of additional rectification and require surplus compression capacity, leading to significant losses and increased capital and operating costs.
Innovation Solution
A novel process that integrates additional rectification using a compact heat and mass transfer system, eliminating the need for additional residue gas compression and reducing capital costs by combining equipment into a single housing, thereby enhancing recovery efficiency and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional cryogenic expansion processes are used for natural gas liquids recovery, then the process provides simplicity and operating flexibility, but the recovery efficiency of C2 and C3 components is insufficient due to lack of additional rectification
Solution Approach 1:
The patent combines the rectification function with the existing cryogenic expansion process by integrating a rectification section into the expansion pathway. The expanded gas stream is directed to a rectification column that separates C2 and C3 components from the methane-rich stream, thereby merging separation functionality into the existing process flow without requiring entirely separate equipment systems.
Solution Approach 2:
The patent segments the cryogenic expansion process into distinct functional zones: an expansion section where pressure reduction occurs, a rectification section where C2 and C3 components are separated from methane, and a recombination section where purified streams are merged. This segmentation allows each section to be optimized independently while improving overall recovery efficiency.
2Productivity
If additional rectification is implemented to improve C2 and C3 component recovery, then separation efficiency increases, but capital costs increase due to additional equipment requirements
Solution Approach 1:
The rectification column is designed to perform multiple functions: it separates C2 components from methane, condenses C3 components, and provides a pathway for recycled liquid to contact and further purify the expanded gas stream. This multi-functionality reduces the need for separate dedicated equipment for each separation task, thereby lowering capital costs.
Solution Approach 2:
The patent implements a nested configuration where a liquid recycle stream is introduced into the rectification column to contact and absorb C2 components from the expanded gas. The liquid recycle system is nested within the existing cryogenic expansion infrastructure, utilizing available cold streams and equipment rather than requiring entirely separate systems.
3Productivity
If surplus compression capacity is added to support additional rectification, then component recovery improves, but operating costs and power consumption increase
Solution Approach 1:
The system uses self-service by directing the expanded gas stream through the rectification column where separation occurs passively based on component volatility differences. The liquid recycle stream automatically contacts the expanded gas to absorb C2 components, utilizing the existing temperature and pressure differentials without requiring additional compression power.
Solution Approach 2:
The patent applies partial action by implementing rectification to the extent necessary to achieve improved C2 and C3 recovery without over-engineering the system. The liquid recycle ratio and rectification column dimensions are optimized to provide sufficient separation while avoiding excessive energy consumption that would result from more aggressive compression or multiple staged rectification systems.
4Device complexity
If equipment is combined into a single housing to reduce capital costs, then device complexity decreases, but manufacturing and maintenance difficulty increases
Solution Approach 1:
The patent merges the rectification column, expansion equipment, and liquid recycle system into a single integrated housing or skid-mounted unit. This consolidation reduces the number of separate equipment items that require installation, alignment, and interconnection, thereby simplifying the overall system while the modular design facilitates standardized manufacturing procedures.
Solution Approach 2:
The integrated equipment is designed and pre-assembled as a complete unit before delivery to the site. Preliminary manufacturing activities including internal piping, instrumentation, and insulation are completed during factory assembly, reducing on-site construction complexity and enabling easier installation and maintenance at the operating location.
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
Achieves C2 recoveries exceeding 97% and C3 recoveries of 99% with reduced power consumption, increasing product recovery and decreasing operating costs, while also minimizing environmental emissions by reducing piping and flanged connections.
Implementation Method 1
a heat and mass transfer system configured to provide additional rectification of the expanded gas stream
Implementation Method 2
a heat and mass transfer system configured to provide additional rectification of the expanded gas stream
Implementation Method 3
a feed gas stream under pressure is cooled by heat exchange with other streams of the process
Implementation Method 4
the cooled liquid stream is expanded through an expansion valve to a lower pressure at which additional liquids are condensed
Implementation Method 5
The vaporization occurring during expansion of the liquids results in further cooling of the stream
Data Source
AI summary
A process and an apparatus are disclosed for a compact processing assembly to improve the recovery of C2 (or C3) and heavier hydrocarbon components from a hydrocarbon gas stream. The preferred method of separating a hydrocarbon gas stream generally includes producing at least a substantially condensed first stream and a cooled second stream, expanding both streams to lower pressure, and supplying the streams to a fractionation tower. In the process and apparatus disclosed, the tower overhead vapor is directed to an absorbing means and a heat and mass transfer means inside a processing assembly. A portion of the outlet vapor from the processing assembly is compressed to higher pressure, cooled and substantially condensed in a heat exchange means inside the processing assembly, then expanded to lower pressure and supplied to the heat and mass transfer means to provide cooling. Condensed liquid from the absorbing means is fed to the tower.