NaY Zeolite PSA for High-Pressure Natural Gas H2S Removal
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Solution Overview
Problem
Current natural gas purification technologies, such as those using amines and iron oxides, are costly and environmentally impactful, and existing PSA processes with zeolites are inefficient for high-pressure H2S removal due to irreversible adsorption and high replacement costs.
Innovation Solution
Utilizing NaY zeolite with a Si/Al ratio greater than 2.6 for H2S removal in a PSA process, allowing partial regeneration by pressure reduction, reducing the need for solid replacement and minimizing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If iron oxides are used for H2S removal, then H2S is removed from the gas stream, but the adsorption is irreversible producing solid waste containing iron sulfide and causing environmental impact
Solution Approach 1:
The patent applies the discarding and recovering principle by enabling the recovery and regeneration of the zeolite adsorbent through pressure reduction. Instead of discarding the adsorbent after use (as with iron oxides that produce irreversible waste), the zeolite can be regenerated in situ by reducing pressure, allowing it to be reused multiple times without producing harmful solid waste.
Solution Approach 2:
The patent utilizes parameter changes by varying the pressure conditions to control the adsorption and desorption processes. By changing pressure from high (during adsorption) to low (during regeneration), the system achieves reversible H2S removal without environmental harm, resolving the contradiction between effective removal and waste generation.
2Reliability
If iron oxides are used for H2S removal, then H2S is removed from the gas stream, but recurrent replacement of the solid represents high cost
Solution Approach 1:
The zeolite adsorbent is recovered and regenerated through pressure reduction rather than being discarded after single use. This eliminates the need for recurrent replacement of the solid adsorbent, significantly reducing operational costs while maintaining reliable H2S removal performance.
Solution Approach 2:
The zeolite adsorbent performs self-service by automatically regenerating itself when pressure is reduced. The adsorbent requires no external intervention or replacement, as it naturally desorbs H2S under reduced pressure conditions and is ready for reuse, eliminating replacement costs.
3Reliability
If conventional PSA processes with zeolites are used, then H2S removal is attempted, but adsorption is irreversible and replacement costs are high
Solution Approach 1:
The patent successfully applies parameter changes by utilizing pressure variation to achieve reversible adsorption. By changing pressure conditions between high (for H2S capture) and low (for regeneration), the zeolite maintains its adsorption capability over multiple cycles without irreversible saturation, eliminating the need for frequent replacement.
Solution Approach 2:
The patent implements periodic action through cyclic pressure changes that alternately promote adsorption and desorption. This periodic pressure cycling allows the zeolite to continuously capture and release H2S, maintaining effectiveness without irreversible adsorption that would require replacement.
4Productivity
If natural gas is processed offshore in pre-salt wells, then natural gas production is achieved, but processing costs increase due to high exploration costs and contamination removal requirements
Solution Approach 1:
The zeolite adsorbent provides self-service by automatically regenerating itself through pressure reduction without requiring external chemicals, energy input, or replacement. This self-regenerating capability significantly reduces processing costs for offshore natural gas production while maintaining productivity.
Solution Approach 2:
The system recovers and reuses the zeolite adsorbent through pressure cycling rather than discarding it after single use. This recovery mechanism eliminates the need for continuous adsorbent replacement, reducing operational costs while maintaining high natural gas production rates.
Data Source
AI summary
The present invention addresses to the use of NaY zeolite with a Si/Al ratio>2.6 as a solid adsorbent in the process of removing H2S from natural gas through a PSA process. The described adsorbent has the capacity of removing H2S from natural gas from offshore exploration platforms, enabling in situ regeneration. The experimental development proved the high capacity of capturing H2S by the NaY zeolite in consecutive cycles of pressurization, adsorption, depressurization and purging. This capture capacity remains at 74.2% of the initial capacity, remaining stable in subsequent cycles. The structure of the material maintained crystallinity above 95% in use, in 15 consecutive cycles, allowing the reuse of the adsorbent for a prolonged period of operation, preventing the solid from being constantly changed, which is quite common in a non-regenerative process.