Steam Cracking Disulfide Oil By-Products in MEROX Refinery

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Solution Overview

Problem

The disposal of disulfide oil (DSO) by-products from the mercaptan oxidation (MEROX) process poses environmental and economic challenges due to their sulfur content and low vapor pressure, making existing disposal methods inefficient and environmentally unacceptable.

Innovation Solution

An integrated refinery process involving the introduction of a hydrocarbon stream with mercaptans into an extraction vessel with an alkaline solution, converting mercaptans to alkali metal alkanethiolates, recovering spent caustic, oxidizing it to produce a by-product stream containing disulfide oils, and processing this stream in a steam cracking unit to generate a DSO-free product stream, thereby converting the DSO into useful products.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If DSO is added to the fuel oil pool, then the disposal problem is simplified, but the sulfur content of the fuel oil pool increases

Engineering Contradiction:

Improvedisposal simplicityVSAvoidsulfur content

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful DSO by-product into valuable chemical feedstocks through steam cracking. The DSO is processed to produce useful products including hydrogen sulfide, carbon disulfide, and aromatic hydrocarbons, transforming a waste disposal problem into a value-generating process that eliminates sulfur content issues in fuel products

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-generated harmful factors

If DSO is processed in a hydrotreating/hydrocracking unit, then the sulfur content is reduced, but hydrogen consumption increases

Engineering Contradiction:

Improvesulfur contentVSAvoidhydrogen consumption

Core Design Contradiction:

Object-generated harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent changes the processing parameters by using steam cracking instead of hydrotreating. This involves high-temperature thermal decomposition (750-950°C) without hydrogen addition, fundamentally changing the chemical transformation mechanism from hydrogenation to pyrolysis, thereby eliminating hydrogen consumption while still reducing sulfur content

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional disposal methods are used, then the process is simple, but environmental acceptability is poor

Engineering Contradiction:

Improveprocess complexityVSAvoidenvironmental acceptability

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent transforms the environmentally problematic DSO waste stream into valuable chemical products through steam cracking. By producing useful commodities like hydrogen sulfide, carbon disulfide, and aromatic hydrocarbons, the process converts an environmental liability into an economic and environmental asset, achieving superior environmental acceptability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 process effectively converts DSO into valuable products like hydrogen sulfide, carbon disulfide, aromatic hydrocarbons, and increased C8 aromatics, addressing the environmental and economic issues associated with DSO disposal while enhancing the value of by-products for refineries.

Implementation Method 1

passing the hydrocarbon stream through an extraction section of the extraction vessel which includes one or more liquid-liquid contacting decks for reaction to convert the mercaptans to alkali metal alkanethiolates

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

subjecting the spent caustic containing alkali metal alkanethiolates to air oxidation to produce a by-product stream containing disulfide oils (DSO) and sulfides

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 3

processing the by-product stream in a steam cracking unit to produce a DSO free product stream

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Data Source

PatentUS11261386B2Conversion of MEROX process by-products to useful products in an integrated refinery process

Publication Date: 2022.03.01 SAUDI ARABIAN OIL CO

AI summary

An integrated refinery process for removing mercaptans from a hydrocarbon stream containing mercaptans and converting by-product disulfide oil to useful products. The process includes introducing the hydrocarbon stream containing mercaptans into an extraction vessel containing an alkaline solution and passing the hydrocarbon stream through an extraction section of the extraction vessel which includes one or more liquid-liquid contacting decks for reaction to convert the mercaptans to alkali metal alkanethiolates. Further, the process includes withdrawing a hydrocarbon product stream free of mercaptans from the extraction vessel and recovering spent caustic containing alkali metal alkanethiolates from the extraction vessel. Additionally, the process includes subjecting the spent caustic containing alkali metal alkanethiolates to air oxidation to produce a by-product stream containing disulfide oils (DSO) and sulfides and processing the by-product stream in a steam cracking unit to produce a DSO free product stream.