Multi-Layer Adsorbent Bed for Oxygen and Sulfur Tolerance
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Solution Overview
Problem
Adsorbent-based systems in LNG dehydration units face premature degradation due to the formation of elemental sulfur and sulfates from the reaction of oxygen and sulfur compounds during regeneration, leading to short bed life and operational issues.
Innovation Solution
A multi-layer adsorbent bed process design that includes a molecular sieve for sulfur removal and a reduced metal oxide for oxygen removal, preventing adverse reactions and extending the life of molecular sieve beds by maintaining low oxygen and sulfur levels in the regeneration gas stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adsorbent beds are used for dehydration in the presence of oxygen and sulfur compounds, then water removal is achieved, but elemental sulfur and sulfates form during regeneration, permanently deactivating the adsorbent and shortening bed life
Solution Approach 1:
The adsorbent bed is divided into multiple functional layers: a molecular sieve layer for water and sulfur compound removal, and a reduced metal oxide layer for oxygen removal. This segmentation allows each layer to target specific contaminants, preventing the formation of harmful sulfur compounds during regeneration while maintaining dehydration functionality.
Solution Approach 2:
The reduced metal oxide layer acts as an intermediary that removes oxygen from the gas stream before it reaches the molecular sieve layer during regeneration. By eliminating oxygen as an intermediary step, the harmful reaction between oxygen and sulfur compounds is prevented, protecting the molecular sieve from deactivation.
2Reliability
If lower regeneration temperatures are used to prevent sulfur and sulfate formation, then adsorbent bed life is extended, but dehydration capacity and regeneration effectiveness are reduced
Solution Approach 1:
The invention changes the chemical composition parameters of the adsorbent bed by introducing reduced metal oxide materials with specific oxygen-removal capabilities. This parameter change allows the system to maintain effective dehydration capacity while operating at lower regeneration temperatures, as the metal oxide layer prevents harmful reactions without compromising the molecular sieve's water removal efficiency.
3Reliability
If multi-layer adsorbent beds with reduced metal oxide are implemented, then oxygen and sulfur removal is achieved preventing harmful reactions, but device complexity increases
Solution Approach 1:
The invention merges multiple contaminant removal functions into a single integrated adsorbent bed structure. The reduced metal oxide layer and molecular sieve layer work together in one bed to remove oxygen, sulfur compounds, and water simultaneously, eliminating the need for separate treatment units and reducing overall system complexity despite the multi-layer configuration.
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 process effectively prevents the formation of elemental sulfur and sulfates, significantly extending the life of molecular sieve beds to meet typical turn-around schedules of three to four years in LNG plants.
Implementation Method 1
sending the dried gas stream to a cooled adsorbent bed containing a first layer of adsorbent to remove sulfur compounds
Implementation Method 2
sending the dried gas stream to a second layer of adsorbent to remove oxygen and oxygen compounds
Implementation Method 3
passing a gas stream through at least one adsorbent bed to remove water and producing a dried gas stream
Data Source
AI summary
A process for treating a gas stream, such as natural gas, comprising a process design that prevents the formation of undesired sulfur and sulfates from the reaction of oxygen and sulfur is disclosed. After water is removed from the gas stream, a portion of the dried gas stream is sent through a cooled adsorbent bed that has a first layer to remove sulfur compounds and then a layer to remove oxygen. There may be additional layers of adsorbent to remove other contaminants. The gas stream that is then heated to regenerate an adsorbent bed no longer contains sulfur and oxygen and undesirable reactions of sulfur and oxygen are avoided.