Enhanced low temperature separation process
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional low temperature separation (LTS) processes for recovering natural gas liquids (NGL) lack selectivity in recovering valuable heavy components and require significant re-compression of light components, leading to high operating costs and inefficient NGL recovery.
Innovation Solution
An enhanced low temperature process that involves cooling a feed stream through heat exchangers, separating it in an absorber, flashing the liquid bottoms into a de-ethanizer tower, and recycling reflux streams to enhance the recovery of C3+ hydrocarbon compounds, thereby reducing the need for external refrigeration and re-compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional LTS processes are used to recover NGL, then the separation of light and heavy hydrocarbon components is achieved, but the selectivity in recovering valuable heavy components (C3+) is insufficient and light components require significant re-compression
Solution Approach 1:
The process segments the hydrocarbon separation into distinct stages: initial cooling and condensation in the heat exchanger, separation in the absorber, and final fractionation in the de-ethanizer tower. This segmentation allows heavy components to be recovered selectively while light components are separated and reused as refrigerant, minimizing re-compression needs
Solution Approach 2:
The de-ethanizer overhead vapor (containing light components) is condensed and the liquid is recycled back to the absorber as reflux. This feedback loop allows light components to be continuously separated and reused, reducing the need for external refrigeration and minimizing re-compression energy consumption
2Ease of operation
If mechanical refrigeration systems are used in LTS processes, then cooling is provided and re-compression is reduced, but the selectivity in recovering specific NGL components cannot be controlled
Solution Approach 1:
The process uses parameter changes in the form of temperature and pressure adjustments at different stages. The feed stream is cooled to specific temperatures in the heat exchanger, the absorber operates at controlled conditions, and the de-ethanizer tower uses temperature gradients to achieve selective separation of C2 from C3+ components, enabling controlled recovery of specific NGL components
Solution Approach 2:
The process exploits phase transitions of hydrocarbon components at different temperatures and pressures. By controlling the temperature in the heat exchanger and absorber, and using the de-ethanizer tower to achieve phase separation, the process selectively condenses and recovers heavy components while maintaining light components in vapor phase for recycling
3Temperature
If expansion-based cooling is used, then refrigeration is provided, but re-compression of product gas is required representing significant capital and operating expense
Solution Approach 1:
The system uses self-service by utilizing the de-ethanizer overhead vapor (containing light components) as the refrigerant source. This vapor is condensed and recycled back to the absorber, creating a self-sustaining refrigeration cycle that eliminates the need for external expansion-based cooling systems and associated re-compression equipment
Solution Approach 2:
Instead of discarding the light components in the de-ethanizer overhead vapor, the process recovers them by condensing and recycling as refrigerant to the absorber. This recovery approach eliminates waste and removes the need for re-compression equipment while maintaining effective cooling
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 process achieves increased selectivity in recovering valuable NGL products like butane and heavier hydrocarbons while reducing operating costs by minimizing refrigerant compression and equipment size, with improved NGL product streams and reduced compressor power requirements.
Implementation Method 1
cooling the feed stream by directing the feed stream through at least one heat exchanger so as to condense at least a portion of the feed stream
Implementation Method 2
condense at least a portion of the feed stream
Implementation Method 3
An absorber overhead vapor stream and an absorber liquid bottoms stream are produced by separation in the absorber
Implementation Method 4
flashing the absorber liquid bottoms stream into a de-ethanizer tower, thereby producing a de-ethanizer overhead vapor stream and a liquid product stream enriched in C3+ hydrocarbon compounds
Implementation Method 5
At least a portion of the de-ethanizer overhead vapor stream is condensed to form a liquid reflux stream
Data Source
AI summary
Enhanced low temperature separation (LTS) processes are provided for separating light hydrocarbon components from heavy hydrocarbon components. The enhanced LTS process utilizes an absorber and a de-ethanizer tower to achieve sufficiently pure natural gas liquid (NGL) products and residue gas products. A portion of the de-ethanizer tower overhead is condensed and recycled as reflux for the absorber. The enhanced LTS process requires less refrigeration of the feed gas stream yet still achieves increased recovery of the valuable heavier hydrocarbons from hydrocarbon gas streams. The enhanced LTS process also reduces compression requirements compared to conventional LTS processes.