N-Butane Chloride Separation Using Integrated Rectification Sections

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Solution Overview

Problem

Existing alkylation processes using ionic liquid catalysts result in high concentrations of organic and inorganic chlorides in the butane product stream, which can shorten the life of chloride treater adsorbents and require frequent replacement, posing environmental and operational challenges.

Innovation Solution

Implementing a rectification section and a stripper section in the separation zone to separate and control organic and inorganic chlorides, allowing for high chloride recovery and minimizing their levels in the butane product stream, thereby eliminating the need for additional chloride treaters in new unit designs and optimizing existing equipment in revamp units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If ionic liquid catalyst is used in alkylation process, then environmental friendliness and catalytic effectiveness are improved, but chloride concentration in butane product stream increases significantly

Engineering Contradiction:

Improveenvironmental harm from traditional catalystsVSAvoidchloride concentration in butane product

Core Design Contradiction:

Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The patent extracts chlorides from the butane product stream by implementing a dedicated rectification section within the fractionation column. This section specifically targets and removes organic chlorides (butyl chloride) and inorganic chlorides (HCl) that were generated during ionic liquid-catalyzed alkylation, thereby preserving the environmental benefits while eliminating the harmful chloride byproducts

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The fractionation column is segmented into multiple functional sections including a rectification section with specific trays dedicated to chloride removal. This segmentation allows the system to simultaneously perform fractionation of hydrocarbons and selective removal of chlorides, addressing the contradiction by creating specialized zones for different separation functions

Inventive Principle:

Principle #1Segmentation

2Device complexity

If conventional fractionation without rectification section is used, then process simplicity is maintained, but chloride removal efficiency is insufficient and treaters require frequent replacement

Engineering Contradiction:

Improvefractionation column configurationVSAvoidchloride treater lifespan

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The rectification section performs preliminary chloride removal within the fractionation column itself, reducing the chloride load before the stream reaches the chloride treaters. This preliminary action extends treater lifespan and reduces maintenance frequency, justifying the added complexity through improved reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The rectification section acts as an intermediary between the alkylation reactor and the chloride treaters, providing a intermediate purification step that reduces chloride concentrations to levels that extend treater life without requiring complete chloride removal, thus balancing complexity and reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If additional chloride treaters are added to handle high chloride loads, then chloride removal capacity is improved, but process complexity and capital cost increase

Engineering Contradiction:

Improvechloride removal capacityVSAvoidnumber of chloride treaters

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent merges the chloride removal function with the existing fractionation column by incorporating a rectification section, thereby combining two separation functions into one unit operation. This eliminates the need for separate additional chloride treaters while maintaining adequate chloride removal capacity, thus improving productivity without increasing device complexity

Inventive Principle:

Principle #5Merging (Combining)

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 process achieves low total chloride content (<0.5 wppm) in the butane product stream, extending the life of chloride treaters and enhancing operational efficiency by reducing reboiling duty and minimizing chloride-related maintenance.

Implementation Method 1

removing chlorides from a liquid or vapor portion of said feed stream in a rectification section of the separation zone

Methodology Applied

Scientific EffectVapor-liquid equilibrium:

Implementation Method 2

separating, in a separation zone, a feed stream comprising light hydrocarbons, propane, isobutane, n-butane, chlorides, and C5+ hydrocarbons

Methodology Applied

Scientific EffectDistillation: Distillation

Implementation Method 3

separating, in a separation zone comprising a fractionation column, a feed stream into a stream comprising light hydrocarbons, propane, isobutane, and n-butane and a liquid stream comprising an alkylate effluent with C5+ hydrocarbons

Methodology Applied

Scientific EffectFractionation: Fractionation

Data Source

PatentUS12378171B2Processes and apparatuses for separating chlorides from n-butane

Publication Date: 2025.08.05 UOP LLC

AI summary

Processes and apparatuses for separating chlorides from a butane product stream by removing chlorides from a portion of said feed stream in a rectification section of the separation zone. The rectification section may be in a rectification column which may be combined with a stripper column. Alternatively, a wall may be used to provide the rectification section in a fractionation column. The processes and apparatuses can be used in both new designs and revamped designs.