TSA Purification via Closed-Loop Regeneration
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Solution Overview
Problem
Existing temperature swing adsorption (TSA) processes face challenges in achieving high purity levels without incurring significant capital and operating costs, particularly due to insufficient purity of waste purge gas, which often requires costly chillers or additional treatment steps to meet purity specifications.
Innovation Solution
Implementing a closed loop regeneration system with a scrubber that reduces contaminant loading in the purge gas from Pc to Ps during the thermal soak phase, allowing for ambient temperature operation and reducing the need for costly chillers or additional treatment steps, while optimizing scrubber design to minimize capital and operating expenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional TSA processes are used with waste purge gas, then operating costs are reduced, but the purity of the regenerated gas is insufficient and requires costly additional treatment
Solution Approach 1:
The TSA process is divided into multiple sequential steps (adsorption, thermal soak, cooling, purge) with each step optimized for specific contaminant removal. The purification process is segmented into multiple passes through the adsorbent bed, with each pass removing different concentrations of contaminants, thereby achieving high purity without requiring expensive single-step treatment equipment.
Solution Approach 2:
The system uses periodic cyclic operation where the adsorbent bed alternates between adsorption and regeneration modes. During the purge step, waste purge gas is periodically introduced to strip contaminants from the adsorbent, and this periodic action allows the system to accumulate purified gas over multiple cycles while using inexpensive waste purge gas rather than requiring continuous expensive treatment.
2Quantity of substance
If chillers are added to meet purity specifications, then gas purity is improved, but capital costs and operating costs increase significantly
Solution Approach 1:
The patent replaces mechanical cooling systems (chillers) with a thermal adsorption-based purification system. Instead of using expensive mechanical refrigeration equipment to cool and purify the waste purge gas, the system uses the natural adsorption characteristics of the adsorbent bed combined with thermal soaking to achieve purification, thereby eliminating the need for capital-intensive chiller equipment.
Solution Approach 2:
The waste purge gas is used to regenerate the adsorbent bed, and in the process, the adsorbent bed simultaneously purifies the gas. The system is self-regenerating where the purge gas itself contributes to the purification process by passing through the adsorbent bed multiple times, removing contaminants through adsorption without requiring external energy-intensive cooling systems.
3Ease of manufacture
If PSA hydrogen is used for regeneration, then operating costs are reduced, but liquid hydrocarbon carryover into downstream processes occurs
Solution Approach 1:
Before the waste purge gas is introduced to the adsorbent bed for regeneration, the system performs a thermal soak step that heats the adsorbent bed to a temperature where liquid hydrocarbons are vaporized. This preliminary action ensures that when the cold waste purge gas is subsequently introduced, it encounters vapor-phase contaminants rather than liquid, preventing liquid hydrocarbon carryover into downstream processes while still using the low-cost PSA hydrogen.
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 approach enables high purity gas production at reduced costs by efficiently removing contaminants, using existing PSA hydrogen, and minimizing hydrocarbon carryover into downstream processes, thus achieving cost-effective and efficient TSA operation.
Implementation Method 1
Gas separation is important in many industries and can typically be accomplished by flowing a mixture of gases over an adsorbent that preferentially adsorbs a more readily adsorbed component relative to a less readily adsorbed component of the mixture
Implementation Method 2
When the temperature of the adsorbent is increased, the adsorbed gas is released, or desorbed
Implementation Method 3
The purge gas stream is cooled in a cooler to a temperature sufficient to condense liquid hydrocarbons and water from the purge gas stream
Data Source
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AI summary
A process for regenerating a temperature swing adsorption unit comprising: sending a heated purge gas stream through an adsorption bed to remove impurities from said adsorption bed and producing a contaminated stream; sending said contaminated stream to a separator to produce a liquid stream and a vapor stream; returning said vapor stream as at least a portion of said heated purge stream until said vapor stream comprises above a predetermined level of impurities; and purging a portion of said vapor stream until the heated purge stream has a level of impurities below a second predetermined level.