Swing Adsorption Dehydration With Partial Pressure Purge
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Solution Overview
Problem
Conventional molecular sieve TSA and PSA processes for natural gas dehydration are inefficient, requiring high pressures, large adsorbent volumes, and high regeneration temperatures, leading to hydrothermal degradation and increased costs, especially in offshore facilities.
Innovation Solution
The implementation of a rapid cycle partial pressure purge swing adsorption (PPSA) process that uses a larger purge gas volume at lower pressures and temperatures, eliminating the need for fired heaters and reducing adsorbent quantity, with the purge stream sourced from the demethanizer overhead stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional molecular sieve TSA process is used for dehydration, then dehydration capability is achieved, but high regeneration temperatures are required causing hydrothermal degradation
Solution Approach 1:
The patent changes the regeneration parameter from high temperature to pressure reduction. Instead of heating the adsorbent bed to high temperatures for regeneration, the system uses pressure swing adsorption where the adsorbent is regenerated by reducing pressure, thereby eliminating hydrothermal degradation while maintaining dehydration capability.
Solution Approach 2:
The patent replaces the thermal field (heating system) with a mechanical field (pressure control system). The TSA process uses thermal energy for regeneration, while the PSA process uses mechanical pressure control, substituting the thermal regeneration mechanism with a pressure-based mechanism to avoid thermal degradation.
2Reliability
If conventional molecular sieve PSA process is used for dehydration, then dehydration capability is achieved, but high pressures are required increasing operational costs
Solution Approach 1:
The patent optimizes the pressure parameters by using partial pressure purge instead of full pressure swing. The system operates at lower pressures by introducing a purge stream that creates a partial pressure differential, reducing the overall operating pressure requirements while maintaining effective water separation.
3Reliability
If conventional dehydration processes are used, then dehydration is achieved, but large adsorbent volumes are required increasing capital costs
Solution Approach 1:
The patent implements a continuous dehydration process using multiple adsorbent beds in sequence. While one bed is being purged or regenerated, another bed continues to dehydrate the feed stream. This continuous operation maximizes the utilization of adsorbent capacity and reduces the total adsorbent volume required compared to batch processes with idle regeneration periods.
Solution Approach 2:
The patent uses periodic switching between multiple adsorbent beds to maintain continuous dehydration. The system cycles through adsorption, purge, and regeneration phases across different beds, ensuring that at least one bed is always in the active dehydration phase, thereby reducing the required adsorbent inventory.
4Reliability
If conventional dehydration processes are used, then dehydration is achieved, but large system footprint is required increasing facility costs
Solution Approach 1:
The patent divides the dehydration system into multiple compact modular adsorbent beds rather than using a single large bed. This segmentation allows for more efficient space utilization, easier arrangement of components, and reduced overall footprint while maintaining the required dehydration capacity through parallel or sequential operation of the segmented units.
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 achieves efficient dehydration with reduced capital and operational costs, smaller footprint, and minimized hydrothermal degradation, while maintaining low water content in the product stream, suitable for cryogenic processing.
Implementation Method 1
passing a gaseous feed stream through an adsorbent bed unit to separate water from the gaseous feed stream
Implementation Method 2
performing one or more purge steps, wherein each of the purge steps comprises passing a purge stream through the adsorbent bed unit in a counter flow direction relative to the flow of the gaseous feed stream
Data Source
AI summary
Provided are apparatus and systems for performing a swing adsorption process. This swing adsorption process may involve passing streams through adsorbent bed units to remove contaminants, such as water, from the stream. As part of the process, the adsorbent bed unit is purged with a purge stream that is provided from the overhead of the demethanizer. The configuration integrates a PPSA dehydration system with a cryogenic recovery system.