Combined TSA PSA Adsorption for LNG Feed Gas Purification
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Solution Overview
Problem
Conventional processes for treating natural gas to LNG specifications face challenges due to the large size, weight, and high operating costs of conventional systems, especially in floating facilities, and the need for frequent replenishment of solvents in amine-solvent based separation systems.
Innovation Solution
A combined temperature swing adsorption (TSA) and pressure swing adsorption (PSA) process that includes adsorption, depressurization, heating, and purge steps to efficiently remove contaminants like CO2 from natural gas, using a heating loop with a blower to increase pressure and create a temperature differential, and recycling the heating stream to enhance contaminant removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If amine-solvent based separation systems are used to remove CO2 from natural gas, then CO2 removal efficiency is improved, but facility size, weight, and capital investment increase significantly
Solution Approach 1:
The patent employs porous adsorbent materials with specific pore structures and surface chemistries that selectively adsorb CO2 from natural gas. The porous structure provides high surface area for adsorption, enabling efficient CO2 removal without requiring large volumes of solvent handling equipment. The adsorbent material's pore size and surface properties are tailored to preferentially capture CO2 molecules while allowing methane and other natural gas components to pass through.
Solution Approach 2:
The system utilizes pressure swing adsorption (PSA) and temperature swing adsorption (TSA) techniques that change physical parameters (pressure and temperature) to control CO2 adsorption and desorption. During the adsorption phase, high pressure promotes CO2 uptake by the adsorbent. During regeneration, pressure is reduced and/or temperature is increased to release CO2 from the adsorbent. This parameter cycling enables continuous operation with compact equipment, avoiding the large footprint of conventional solvent-based systems.
2Manufacturing precision
If amine-solvent based separation systems are used to remove CO2 from natural gas, then CO2 removal efficiency is improved, but operating costs increase due to frequent solvent replenishment
Solution Approach 1:
The pressure swing and temperature swing mechanisms enable cyclic operation where the adsorbent is regenerated in-situ by changing pressure and temperature conditions. During the swing phase, pressure is reduced and/or temperature is increased to desorb CO2 from the adsorbent material. This allows the same adsorbent bed to be reused continuously without solvent depletion, eliminating the need for frequent solvent replenishment and associated operating costs.
Solution Approach 2:
The adsorbent material performs self-regeneration through the pressure and temperature swing process. The system uses a portion of its own output (purge gas or process gas) to facilitate the desorption and regeneration of the adsorbent, creating a self-sustaining cycle that does not require external solvent replacement. The adsorbent automatically transitions between adsorption and desorption states based on the applied pressure and temperature conditions.
3Manufacturing precision
If conventional separation systems are used for LNG feed preparation, then CO2 removal is achieved, but facility footprint and complexity increase
Solution Approach 1:
The patent combines pressure swing adsorption and temperature swing adsorption into a single integrated system. The PSA and TSA processes are merged such that the adsorption, desorption, and regeneration steps occur within the same adsorbent beds through coordinated pressure and temperature cycling. This integration eliminates the need for separate solvent handling trains, heat exchangers, and associated equipment, significantly reducing facility footprint while maintaining CO2 removal capability.
Solution Approach 2:
The use of high-performance porous adsorbent materials with optimized pore structures enables compact adsorbent beds that achieve the required CO2 removal capacity in a smaller volume. The porous material's high surface area to volume ratio allows efficient mass transfer and CO2 capture within compact equipment, reducing the overall facility footprint compared to conventional separation systems.
4Productivity
If rapid cycle adsorption processes are implemented, then productivity and contaminant removal efficiency are improved, but process complexity and control requirements increase
Solution Approach 1:
The system employs periodic pressure and temperature swings to drive the adsorption and desorption cycles. The pressure swing involves alternating between high-pressure adsorption mode and low-pressure desorption mode. The temperature swing involves periodic heating during desorption and cooling during adsorption. These periodic actions are coordinated through automated control systems that sequence the pressure and temperature changes, enabling rapid cycle operation while managing complexity through standardized control protocols.
Solution Approach 2:
The rapid cycle PSA-TSA process maintains continuous productive action by overlapping adsorption and regeneration steps across multiple adsorbent beds. While one bed is adsorbing CO2, another bed is being regenerated. The cyclic operation is continuous rather than batch, with beds transitioning between modes in a coordinated sequence. This continuity maximizes productivity by ensuring that adsorption capacity is constantly being utilized while regeneration occurs in parallel, reducing overall cycle time and increasing contaminant removal rate.
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 process reduces the size, weight, and capital investment of facilities, achieves efficient contaminant removal with lower operating costs, and complies with stringent LNG specifications, particularly for CO2 content, while minimizing the use of solvents and emissions.
Implementation Method 1
Gas separation is useful in many industries and can typically be accomplished by flowing a mixture of gases over an adsorbent material that preferentially adsorbs one or more gas components while not adsorbing one or more other gas components. The non-adsorbed components are recovered as a separate product.
Implementation Method 2
PSA processes rely on the phenomenon of gases being more readily adsorbed within the pore structure or free volume of an adsorbent material when the gas is under pressure. That is, the higher the gas pressure, the greater the amount of readily-adsorbed gas adsorbed. When the pressure is reduced, the adsorbed component is released, or desorbed from the adsorbent material.
Implementation Method 3
the heating step comprises passing a heating stream at a heating temperature into the adsorbent bed unit, wherein the heating stream is passed in a countercurrent direction relative to the direction of the feed stream and the heating temperature is less than 500 °F (260 °C) (e.g., which may heat only a portion of the bed), wherein the heating step results in a temperature differential in a range between 50 °F (27.8 °C) and 400 °F (222.2 °C)
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5C
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 treat the pipeline quality natural gas to form a stream that complies with liquefied natural gas (LNG) specifications. The process may involve a combined TSA and PSA process, which is utilized to remove contaminants from the feed stream.