Cryogenic Air Pre-Purification for Ultra-Low Propane Removal
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Solution Overview
Problem
Current pre-purification units for cryogenic air separation units are ineffective in removing ultra-low concentrations of hydrocarbons like propane, which poses safety risks due to its high danger level and low solubility in liquid oxygen, and existing adsorbents struggle to efficiently adsorb and regenerate hydrocarbons at low temperatures.
Innovation Solution
A TSA pre-purification unit is designed with a column packed sequentially with activated alumina, NaX zeolite, and a hydrocarbon adsorbent with a H-FER or MFI structure, where the pore diameter is adjusted by ion exchange to effectively adsorb and desorb hydrocarbons, particularly propane, at low concentrations and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pre-purification units with activated alumina and NaX zeolite are used, then water and carbon dioxide are effectively removed, but ultra-low concentrations of hydrocarbons like propane cannot be removed
Solution Approach 1:
The pre-purification unit is divided into multiple functional sections with different adsorbents: activated alumina for water removal, NaX zeolite for carbon dioxide removal, and FER/MOR zeolite for hydrocarbon removal. Each section targets specific components, enabling comprehensive purification that addresses both the reliability requirement (safety) and the productivity requirement (hydrocarbon removal efficiency).
Solution Approach 2:
The invention uses composite adsorbent systems combining different zeolite types (FER structure and MOR structure) with specific ion exchange compositions. These composite materials provide synergistic effects where each component contributes to removing different impurities, achieving both high safety reliability and effective hydrocarbon removal productivity that single adsorbents cannot accomplish.
2Quantity of substance
If existing adsorbents are used to adsorb hydrocarbons at low temperatures, then some hydrocarbon removal is achieved, but adsorption quantity is insufficient and regeneration is difficult
Solution Approach 1:
The FER and MOR zeolites are subjected to specific ion exchange treatments that modify their chemical parameters and pore properties. This parameter optimization enables the adsorbents to achieve high adsorption quantities for hydrocarbons at low temperatures while maintaining regenerability through thermal treatment, resolving the contradiction between adsorption capacity and regeneration ease.
3Quantity of substance
If the pore diameter of zeolite is not adjusted, then the structure is simple and easy to manufacture, but adsorption selectivity and capacity for ultra-low concentration hydrocarbons are poor
Solution Approach 1:
The invention applies local quality modification by performing ion exchange specifically on the FER and MOR zeolite structures to adjust pore diameter in the regions critical for hydrocarbon adsorption. This targeted modification enhances adsorption capacity for propane while maintaining the overall structural simplicity and manufacturability of the adsorbent material.
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 solution enables efficient removal of ultra-low propane concentrations from air, reducing hydrocarbon levels in liquid oxygen and ensuring safety by achieving effective adsorption and regeneration at low temperatures, with adsorption quantities exceeding conventional methods by more than six times for propane.
Implementation Method 1
a TSA pre-purification unit having a column packed with a hydrocarbon adsorbent containing a zeolite with a H-FER structure or a MOR structure in which the pore diameter has been adjusted by ion exchange
Implementation Method 2
the pore diameter has been adjusted by ion exchange to effectively adsorb and desorb hydrocarbons, particularly propane, at low concentrations and temperatures
Implementation Method 3
a hydrocarbon adsorbent containing a zeolite with a H-FER structure or a MOR structure in which the pore diameter has been adjusted by ion exchange
Data Source
AI summary
A hydrocarbon adsorbent that includes a zeolite with either a H-FER structure or a MOR structure in which the pore diameter has been adjusted by ion exchange. A propane adsorbent that includes a zeolite with a MFI structure. A hydrocarbon removal unit that includes a TSA pre-purification unit having a column packed with sequential layers of activated alumina, a NaX zeolite, and the hydrocarbon adsorbent. A method of reducing the hydrocarbon content within liquid oxygen inside a cryogenic air separation unit that includes purifying feed air with the above pre-purification unit.