Steam Cracker Feedstock Segmentation for Asphaltene Control

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Solution Overview

Problem

Conventional steam cracking processes face issues with asphaltene precipitation in hydrocarbon feedstocks, leading to fouling and inefficiencies in refinery equipment due to inconsistency in feedstock composition.

Innovation Solution

A process involving continuous separation of hydrocarbon feedstocks into volatile and non-volatile streams, where a portion of the non-volatile stream is recycled back to the feedstock, utilizing a vapor-liquid separator and steam cracker to reduce asphaltene precipitation by enhancing solubility and compatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional steam cracking is used with varied hydrocarbon feedstocks, then processing flexibility is maintained, but asphaltene precipitation occurs leading to equipment fouling and operational inefficiency

Engineering Contradiction:

Improvefeedstock flexibilityVSAvoidasphaltene precipitation and fouling

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The feedstock stream is segmented into two distinct phases using a vapor-liquid separator: a volatile overhead stream containing lighter hydrocarbons and a non-volatile bottoms stream containing heavier components including asphaltenes. This segmentation prevents asphaltene precipitation by maintaining compositional homogeneity within each phase while allowing the bottoms stream to be recycled as a compatibilizer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A portion of the non-volatile bottoms stream is recycled back to the feedstock inlet and mixed with incoming feedstocks. This feedback loop maintains asphaltene solubility by ensuring consistent composition and compatibility in the mixed feedstock, preventing precipitation in the steam cracker while allowing processing of varied feedstock sources.

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If multiple feedstocks with different compositions are processed, then feedstock versatility is achieved, but incompatibility and precipitation occur

Engineering Contradiction:

Improvefeedstock composition varietyVSAvoidfeedstock compositional consistency

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The recycled non-volatile bottoms stream acts as an intermediary substance that mediates between different feedstock compositions. By mixing this recycled stream with incoming varied feedstocks, it serves as a compatibilizer that maintains overall compositional consistency and prevents incompatibility-driven precipitation, enabling processing of diverse feedstocks.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The recycling process changes the compositional parameters of the mixed feedstock by continuously adjusting the blend ratio of incoming feedstocks to the recycled bottoms stream. This dynamic parameter adjustment ensures that the final mixed feedstock maintains stable composition characteristics that prevent asphaltene precipitation while accommodating varied feedstock inputs.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If asphaltene precipitation is allowed to occur, then processing simplicity is maintained, but energy loss and equipment fouling increase

Engineering Contradiction:

Improveprocess simplicityVSAvoidheat transfer efficiency loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The vapor-liquid separator extracts and removes the non-volatile components containing asphaltenes from the volatile feedstock stream before cracking. By taking out these problematic components and recycling them separately rather than allowing them to precipitate in the cracker, the process prevents fouling and energy loss while adding only one separation unit to the system.

Inventive Principle:

Principle #2Taking out (Extraction)

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

Substantially reduces or eliminates asphaltene precipitation, thereby minimizing energy loss, equipment fouling, and operational inefficiencies, while maintaining economic benefits.

Implementation Method 1

passing the feedstock through a vapor-liquid separator in which the feedstock is separated into a volatile stream and a non-volatile stream

Methodology Applied

Scientific EffectVapor-liquid separation: Distillation

Implementation Method 2

recycling a portion of the non-volatile stream to the feedstock... to reduce asphaltene precipitation by enhancing solubility and compatibility

Methodology Applied

Scientific EffectSolubility enhancement: Solvation

Data Source

PatentUS9725657B2Process for enhancing feed flexibility in feedstock for a steam cracker

Publication Date: 2017.08.08 EXXONMOBIL CHEMICAL PATENTS INC

AI summary

Provided is a process for cracking a hydrocarbon feedstock. The process having the steps of (a) continuously passing the feedstock through a vapor-liquid separator in which the feedstock is separated into a volatile stream and a non-volatile stream; (b) continuously passing the non-volatile stream to a cracker; and (c) continuously recycling a portion of the volatile stream to the feedstock. There is also an apparatus for cracking a hydrocarbon feedstock.