Pre-Purification Unit Zeolite Capping Layer for Propane Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional pre-purification units in air separation units fail to effectively remove propane, leading to enrichment in the main condenser-reboiler, posing a fire hazard and increasing operational and economic costs, while existing solutions with high barium-exchanged zeolites incur high costs and environmental hazards.
Innovation Solution
A three-layer pre-purification unit with a barium-exchanged zeolite capping layer, having a barium exchange level of 10% to 50%, is used to remove propane, accompanied by activated alumina and NaX zeolite layers, reducing bed size and barium usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an increased layer of sodium-exchanged zeolite is used to remove propane, then propane removal capacity is improved, but the size of the adsorbent bed and overall capital and operating costs increase
Solution Approach 1:
The patent uses a composite adsorbent system combining sodium-exchanged zeolite X (for CO2 removal) with barium-exchanged zeolite X (for propane removal). This composite approach allows each adsorbent to target specific contaminants, achieving effective propane removal with a smaller overall bed volume compared to using only sodium-exchanged zeolite.
Solution Approach 2:
The patent applies different adsorbent materials with specific local properties to different functional requirements: sodium-exchanged zeolite for CO2 removal and barium-exchanged zeolite for propane removal. This localized functional assignment optimizes the performance of each adsorbent layer while minimizing total bed size.
2Reliability
If highly exchanged barium zeolite is used to remove propane, then propane removal capacity is improved, but costs and environmental hazards increase
Solution Approach 1:
The patent uses a lower level of barium exchange (10-50% barium on an equivalent basis) compared to prior art solutions that used highly exchanged barium zeolite. This reduced barium content maintains adequate propane removal capacity while decreasing environmental hazards and disposal costs associated with highly exchanged barium zeolite.
Solution Approach 2:
The patent changes the barium exchange level parameter from the high levels used in prior art to a moderate range (10-50%), achieving a balance between propane removal effectiveness and environmental sustainability, thereby reducing the harmful effects of excessive barium content.
3Ease of manufacture
If conventional PPU designs are used, then capital costs are reduced, but propane enrichment in the main condenser-reboiler increases fire hazard
Solution Approach 1:
The patent implements a multi-layer composite adsorbent system that effectively removes propane before it reaches the main condenser-reboiler, eliminating the fire hazard while maintaining cost-effectiveness through optimized adsorbent selection and configuration.
Solution Approach 2:
The pre-purification unit acts as an intermediary system between the feed air stream and the main condenser-reboiler, removing propane contaminants before they can create hazardous conditions in the distillation column system.
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 system achieves efficient propane removal, minimizing fire hazards and costs, while reducing adsorbent bed size and environmental impact, with improved kinetics and lower capital and operating expenses.
Implementation Method 1
a third adsorbent layer disposed in the pre-purification vessel adjacent to the second adsorbent layer and configured to remove propane from the second intermediate effluent. The third adsorbent layer is a barium-exchanged zeolite capping layer
Implementation Method 2
a first adsorbent layer disposed in the pre-purification vessel and configured to remove water from the stream of feed air
Implementation Method 3
a second adsorbent layer disposed in the pre-purification vessel adjacent to the first adsorbent layer and configured to remove carbon dioxide from the first intermediate effluent
Data Source
AI summary
A system and method of propane removal in a pre-purification unit (PPU) for an air separation unit is provided. The disclosed system and method involves the use of a capping layer of zeolite exchanged with moderate amounts of barium cations, preferably a barium exchange level of 50% on an equivalent basis. This reduced or moderate level of barium exchange achieves the required propane removal but with reduced costs and reduced environmental hazards compared to prior art solutions using highly exchanged barium levels. The barium containing zeolite for the capping layer is preferably in an agglomerated form, including beads and/or pellets, having an average particle size in a range of about 1 mm to 5 mm.