Mixed Adsorbent Desiccant Beds for Gas Dehydration
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Solution Overview
Problem
Existing methods for removing water from natural gas streams, particularly in adsorption beds, face challenges such as repeated exposure to elevated temperatures and refluxing water, which accelerates the deterioration of adsorbent beds, and are inefficient in achieving complete dehydration.
Innovation Solution
A mixed adsorbent/desiccant bed configuration is introduced, where from 0 to 99% of the bed volume contains desiccants with substantially no adsorbents, and the remaining volume contains a mixture of adsorbents and desiccants in specific volume ratios, effectively managing water removal and reducing free water during thermal regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thermal swing regeneration is used to remove water from gas streams, then water removal capacity is improved, but adsorbent bed deterioration accelerates due to repeated exposure to elevated temperatures and refluxing water
Solution Approach 1:
The adsorbent bed is segmented into multiple zones with different material compositions. The lower portion contains hydrophobic adsorbents that resist water reflux during regeneration, while the upper portion contains hydrophilic desiccants for efficient water removal. This segmentation allows each zone to perform its specific function, resolving the contradiction between water removal capacity and bed lifespan.
Solution Approach 2:
The patent uses composite material configurations by combining hydrophobic adsorbents (such as silica gel, alumina) with hydrophilic desiccants (such as molecular sieves, zeolites) in specific arrangements. This composite approach enables the bed to simultaneously achieve high water removal capacity during adsorption and resistance to water reflux damage during regeneration, thus extending bed lifespan.
2Measurement precision
If conventional adsorbent beds are used for complete dehydration, then water removal efficiency is improved, but free water remains during thermal regeneration causing refluxing
Solution Approach 1:
The hydrophobic adsorbent acts as an intermediary layer that prevents free water from reaching and refluxing into the hydrophilic desiccant portion during thermal regeneration. This intermediary function allows complete dehydration to be achieved while blocking the harmful refluxing water, thus eliminating the contradiction between dehydration completeness and refluxing prevention.
Solution Approach 2:
The patent converts the harmful effect of free water during regeneration into a beneficial feature by using hydrophobic materials that selectively interact with water. The hydrophobic portion allows water to pass through during adsorption for complete dehydration, then repels that same water during regeneration, preventing refluxing. This transforms the potential harm of free water into a protective mechanism.
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 configuration enhances the capacity of the adsorbent bed during thermal regeneration, reduces free water, and extends the bed's lifespan by preventing refluxing water, resulting in a more efficient and durable water removal process.
Implementation Method 1
Adsorption of contaminants from a gas mixture through solid adsorbents is a thermal exothermic process, known as thermal swing adsorption (TSA)
Implementation Method 2
a mixed adsorbent/desiccant bed effective for removing water from a wet gas stream
Implementation Method 3
The adsorbent must at times be regenerated, accomplished by applying heat, which serves to remove adsorbed material from the internal surface and pores of the adsorbent
Data Source
AI summary
Mixed adsorbent/desiccant beds comprising in some embodiments from about 20 vol % (volume percent) to about 90 vol % of one or more adsorbents and from about 10 vol % to about 80 vol % of one or more desiccants, based on the total volume of the adsorbent/desiccant mixture, prevent water reflux during thermal regeneration of adsorption beds in gas processing plants and methods.