TSA PSA Process for Heavy Hydrocarbon Removal
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Solution Overview
Problem
Existing processes for removing water and hydrocarbons from natural gas streams, such as thermal swing adsorption, face inefficiencies due to recycling issues and the buildup of heavy hydrocarbons, which can lead to increased energy consumption and reduced adsorption efficiency, making it difficult to achieve a low enough cricondentherm for pipeline transportation.
Innovation Solution
A process combining thermal swing adsorption (TSA) with pressure swing adsorption (PSA), where the gas phase from TSA is treated in a PSA unit to remove heavy hydrocarbons, and the low-pressure contaminant stream from PSA is used as fuel for TSA regeneration, improving efficiency by reducing heavy hydrocarbon content and allowing for precise control of cricondentherm levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal swing adsorption is used to remove water and hydrocarbons, then contaminants are removed from natural gas stream, but heavy hydrocarbons build up in the recycle stream reducing adsorption efficiency
Solution Approach 1:
The single adsorption bed is segmented into two beds operating in sequence: first bed for adsorption of water and hydrocarbons, second bed for regeneration. This allows continuous operation without contaminant buildup in recycle streams, maintaining adsorption efficiency indefinitely.
Solution Approach 2:
The harmful heavy hydrocarbons are extracted from the recycle stream by condensing them in a cooler and separating them in a separator. This prevents the buildup that would otherwise reduce adsorption efficiency in subsequent cycles.
2Reliability
If adsorbent bed is regenerated by heating, then adsorbed contaminants are removed, but energy consumption increases
Solution Approach 1:
The energy-rich heavy hydrocarbon contaminants that were previously wasted are now converted into a beneficial fuel source. These contaminants are combusted in a furnace to generate the heat required for regenerating the adsorbent bed, eliminating the need for external energy input and making the process self-sufficient.
3Manufacturing precision
If cricondentherm is lowered for pipeline compliance, then natural gas meets transportation specifications, but more stringent separation is required increasing process complexity
Solution Approach 1:
The dual-bed system enables continuous adsorption while one bed is regenerated, providing uninterrupted contaminant removal. This continuous operation maintains precise cricondentherm control without requiring complex batch processing or multiple separation stages.
Solution Approach 2:
The system uses its own output (heavy hydrocarbon contaminants) to fuel its own regeneration process through combustion in the furnace. This self-service approach eliminates the need for external energy sources and simplifies the overall process while maintaining precise cricondentherm control.
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 combined process effectively reduces the cricondentherm of the natural gas stream, improving energy efficiency and extending adsorbent bed life by minimizing heavy hydrocarbon buildup, enabling the removal of both water and hydrocarbons to achieve desired cricondentherm levels for pipeline compliance.
Implementation Method 1
the natural gas stream is contacted with an adsorbent bed in order to remove the water and hydrocarbon contaminants
Implementation Method 2
If the heat applied is sufficient, the adsorbed components will leave the adsorbent internal surface and pores
Implementation Method 3
the second gas stream to a gas/liquid separation step comprising cooling the second gas stream to a temperature such that at least some contaminants begin to condense into a first liquid phase
Data Source
AI summary
A process for removing heavy hydrocarbons from a natural gas stream comprises passing the natural gas stream thought a TSA adsorbent unit to adsorb heavy hydrocarbons, regenerating the TSA adsorbent by heating to form a contaminant-containing gas phase, cooling the contaminated gas phase to separate water and heavy hydrocarbon liquids to form a third gas phase and directing the third gas phase to a PSA unit to adsorb heavy hydrocarbons from the third gas phase. The product from the PSA unit can be sent to pipeline or recycled to the TSA unit for further hydrocarbon removal and recovery.