System and method for propane removal in pre-purification units

A three-layer pre-purification unit with activated alumina, NaX zeolite, and barium-exchanged zeolite layers efficiently removes propane from air separation units, addressing safety and cost issues by extending propane breakthrough times and reducing adsorbent bed size.

WO2026019454A1 Publication Date: 2026-01-22PRAXAIR TECH INC
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Patent Information

Application Number
PCT/US2025/018103
Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
Priority Date
2024-07-19
Filing Date
2025-03-03
Publication Date
2026-01-22

AI Technical Summary

Technical Problem

Conventional pre-purification units in air separation units (ASUs) fail to adequately remove propane, leading to its enrichment in the liquid oxygen of the main condenser-reboiler, posing a fire hazard and increasing operational and economic costs due to the need for oxygen drainage and refrigeration loss.

Method used

A three-layer pre-purification unit design using a first layer of activated alumina, a second layer of NaX zeolite, and a third layer of barium-exchanged zeolite with 10-50% barium exchange, configured to sequentially remove water, carbon dioxide, and propane from the feed air stream.

Benefits of technology

The system effectively reduces propane levels, minimizing fire hazards and costs by achieving prolonged propane breakthrough times and allowing for smaller adsorbent beds, thus reducing capital and operating expenses while minimizing environmental hazards from barium use.

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Abstract

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.
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