Steam Cracker Primary Fractionator Stabilization via Make-up Liquid

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Solution Overview

Problem

Steam cracker primary fractionators experience unstable operation due to differences in hydrocarbon feed types, leading to insufficient production rates of steam cracker gas oil and tar streams, which can result in fouling and equipment shutdowns.

Innovation Solution

Introducing a make-up liquid stream into the primary fractionator, comprising a first and second hydrocarbon portion, distributed into the gas oil and tar streams respectively, to stabilize operation by ensuring minimum production rates are met, and optionally recycling streams from fluidized catalytic crackers or cokers to adjust the hydrocarbon composition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the steam cracker primary fractionator is designed for liquid hydrocarbon feed, then it can process liquid feeds effectively, but it cannot maintain stable operation when processing gaseous hydrocarbon feeds due to insufficient production rates of gas oil and tar streams

Engineering Contradiction:

Improvefeed type flexibilityVSAvoidoperational stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A make-up liquid stream is introduced as an intermediary substance into the fractionator when processing gaseous feeds. This make-up stream serves as a mediator that provides the necessary liquid hydrocarbon components to maintain stable operation and meet minimum production rates of gas oil and tar streams, effectively bridging the gap between gaseous feed input and liquid product requirements

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the steam cracker primary fractionator is designed for gaseous hydrocarbon feed, then it can process gaseous feeds effectively, but it cannot maintain stable operation when processing liquid hydrocarbon feeds due to insufficient production rates of gas oil and tar streams

Engineering Contradiction:

Improvefeed type flexibilityVSAvoidgas oil and tar production rate

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The composition and flow rate parameters of the make-up liquid stream are adjusted based on the feed type being processed. When liquid hydrocarbon feeds are used, the make-up stream parameters are modified to supplement the insufficient gas oil and tar production, ensuring that productivity requirements are met while maintaining operational stability

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the hydrocarbon feed composition varies, then the steam cracker can process different feed types, but the primary fractionator operation becomes unstable due to insufficient gas oil and tar stream production

Engineering Contradiction:

Improvefeed composition variabilityVSAvoidfractionator operation stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A feedback mechanism is implemented where the composition and flow rate of the make-up liquid stream are dynamically adjusted based on the actual feed composition and fractionator performance. This feedback control ensures that the make-up stream compensates for variations in feed composition, maintaining stable fractionator operation and preventing fouling conditions

Inventive Principle:

Principle #23Feedback

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 introduction of the make-up liquid stream stabilizes the operation of the steam cracker primary fractionator, preventing fouling and ensuring consistent production of steam cracker gas oil and tar streams, thereby maintaining process stability and efficiency.

Implementation Method 1

The make-up liquid stream can include a first hydrocarbon portion and a second hydrocarbon portion. The first hydrocarbon portion can be distributed into the SCGO side stream. The second hydrocarbon portion can be distributed into the SCT stream.

Methodology Applied

Scientific EffectHydrocarbon distribution:

Implementation Method 2

The products are typically separated via a fractionator commonly referred to as a steam cracker primary fractionator

Methodology Applied

Scientific EffectFractionation: Fractionation

Data Source

PatentUS20240360369A1Processes and Systems for Stabilizing Operation of a Steam Cracker Primary Fractionator

Publication Date: 2024.10.31 EXXONMOBIL TECHNOLOGY & ENGINEERING CO

AI summary

Processes and systems for stabilizing the operation of a steam cracker primary fractionator. In some embodiments, the process can include (I) feeding a first steam cracker effluent into a steam cracker primary fractionator. The process can also include (II) feeding a make-up liquid stream into the steam cracker primary fractionator. The process can also include (III) recovering a steam cracker gas oil (“SCGO”) side stream from the steam cracker primary fractionator. The process can also include (IV) recovering a steam cracker tar (“SCT”) stream from a location at and/or in the vicinity of a bottom of the primary fractionator. The make-up liquid stream can include a first hydrocarbon portion and a second hydrocarbon portion. The first hydrocarbon portion can be distributed into the SCGO side stream. The second hydrocarbon portion can be distributed into the SCT stream.