Capacitor Adsorber for Stabilizing Regeneration Gas CO2 Peaks
Solution Overview
Problem
The spent regeneration gas from thermal swing adsorption (TSA) processes in LNG peak shaver plants has fluctuating CO2 concentrations, making it unsuitable for use as fuel in downstream units without further processing, due to dynamic composition variations and peak CO2 levels several orders higher than average, leading to unstable operation.
Innovation Solution
A fixed-bed adsorber, or 'capacitor', operating at elevated temperatures (around 100°C) is used to process the spent regeneration gas from TSA or TPSA units, smoothing out CO2 composition peaks by utilizing 4A or 13X molecular sieve adsorbents, allowing for a more uniform CO2 composition in the fuel gas stream, which can then be used directly in downstream units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If spent regeneration gas is used directly as fuel in downstream units, then energy utilization is improved, but operational stability deteriorates due to fluctuating CO2 concentrations
Solution Approach 1:
The patent applies preliminary action by introducing a capacitor unit before the downstream fuel processing units. This capacitor pre-processes the spent regeneration gas by absorbing excess CO2 during low-concentration periods, thereby stabilizing the CO2 levels before the gas reaches downstream units. This anticipatory measure prevents operational instability rather than reacting to it after occurrence.
Solution Approach 2:
The capacitor acts as an intermediary component between the TSA unit and downstream fuel processing units. It mediates the fluctuating CO2 concentrations by absorbing excess CO2 and releasing it gradually, thus buffering the impact on downstream units and enabling stable operation while utilizing the spent regeneration gas as fuel.
2Productivity
If spent regeneration gas with peak CO2 concentrations is processed through downstream units, then fuel utilization is improved, but equipment reliability deteriorates due to combustion instability
Solution Approach 1:
The capacitor provides beforehand cushioning by absorbing excess CO2 during low-concentration periods and releasing it during high-concentration periods. This cushioning effect smooths out the CO2 concentration peaks before they reach downstream combustion equipment, preventing operational instability and equipment damage while maintaining continuous fuel utilization.
3Device complexity
If no further processing is applied to spent regeneration gas, then process complexity is reduced, but fuel suitability deteriorates due to CO2 concentration fluctuations
Solution Approach 1:
The patent applies the extraction principle by removing the problematic CO2 concentration fluctuations from the spent regeneration gas stream through the capacitor. The capacitor selectively absorbs excess CO2, extracting the instability component while leaving the fuel properties intact, thereby simplifying the overall process while improving fuel suitability.
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 capacitor effectively stabilizes the CO2 concentration in the spent regeneration gas, ensuring a consistent Wobbe Index within acceptable limits, making the gas suitable for use as fuel, reducing operational instability and enabling its direct application in downstream processing units.
Implementation Method 1
A first adsorption bed is used to remove water, heavy hydrocarbons, and aromatic compounds from a natural gas stream to produce a partially purified gas stream. A second adsorption bed is used to remove carbon dioxide and C7− hydrocarbons from the partially purified gas stream.
Implementation Method 2
smoothing out CO2 composition peaks by utilizing 4A or 13X molecular sieve adsorbents
Data Source
AI summary
This invention provides a method to smooth out the concentration peak generated from the regeneration stream of a cyclic adsorption process such as PTSA or TSA process. A fixed-bed adsorber (called a capacitor) to process the spent regeneration gas from a TPSA or TSA unit to maintain a constant composition of the spent regeneration gas to the downstream unit. The adsorber operates in a once-through non-cyclic manner, very similar to the conventional fixed bed reactor or adsorber. The spent regeneration gas stream coming out of the adsorber will have a more uniform CO2 composition than without the capacitor.