Dividing Wall Debutanizer for FCC Naphtha Recovery

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Solution Overview

Problem

Current fluid catalytic cracking (FCC) processes face inefficiencies in energy usage and product recovery, particularly in the separation of naphtha cuts, which limits the overall energy and capital savings in gas recovery sections.

Innovation Solution

Integration of a debutanizer column and a naphtha splitter column into a single dividing wall column, with recycling of light naphtha from the debutanizer column to a primary absorber for enhanced energy efficiency and cleaner product cuts, reduces energy requirements and improves the recovery of valuable hydrocarbons.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple separate columns (debutanizer and naphtha splitter) are used for naphtha fractionation, then product separation capability is improved, but device complexity and capital cost increase

Engineering Contradiction:

Improveproduct separation capabilityVSAvoidnumber of columns

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines the debutanizer column and naphtha splitter column into a single integrated fractionation column. This merging of two separate units into one column reduces device complexity and capital cost while maintaining the ability to produce multiple naphtha cuts through strategic side-draws and product withdrawal points within the unified column structure.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated fractionation column performs multiple functions that traditionally required separate columns. It simultaneously conducts debutanization (removing C4 and lighter components) and naphtha splitting (separating naphtha into light, middle, and heavy cuts) within a single column, making the unit versatile and multi-functional.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Loss of energy

If conventional separate columns are used for fractionation, then capital cost is increased, but energy recovery opportunities are lost

Engineering Contradiction:

Improveenergy recoveryVSAvoidcolumn configuration

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The integrated column enables continuous heat recovery and utilization throughout the fractionation process. By combining multiple separation functions in one column, the design allows for more effective heat integration where heat from higher sections can be utilized in lower sections, maintaining continuous useful thermal action and reducing energy loss.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The patent recovers and utilizes heat that would otherwise be discarded in conventional separate column configurations. The integrated design allows for heat exchange between different sections of the column, recovering thermal energy from product streams and using it to preheat feeds or maintain column temperature profiles, thereby reducing external heating requirements.

Inventive Principle:

Principle #34Discarding and recovering

3Reliability

If light naphtha is recycled to primary absorber, then absorption efficiency is improved, but energy consumption increases

Engineering Contradiction:

Improveabsorption efficiencyVSAvoidrecycle energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements a feedback mechanism where light naphtha is recycled from the integrated fractionation column back to the primary absorber. This feedback loop ensures that any light hydrocarbons not absorbed in the first pass are recovered in the second pass, improving overall absorption efficiency and product recovery while managing energy consumption through the integrated heat management of the unified column.

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

This configuration achieves a 20% reduction in total heating duty and more efficient separation of naphtha cuts, enhancing the energy efficiency of the gas recovery section while maintaining product yields comparable to conventional systems.

Implementation Method 1

A stripped liquid stream is fractionated in a dividing wall debutanizer column to provide an LPG stream, a light naphtha stream and a heavy naphtha stream

Methodology Applied

Scientific EffectDistillation: Distillation

Implementation Method 2

recycling of light naphtha from the debutanizer column to a primary absorber for enhanced energy efficiency

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentUS8747654B2Process for recovering catalytic product

Publication Date: 2014.06.10 UOP LLC

AI summary

A process is disclosed for recovering product from catalytically converted product streams. An integrated debutanizer column provides an LPG stream, a light naphtha stream and a heavy naphtha stream. The integrated debutanizer column may comprise a dividing wall column. The light naphtha stream may be used as an absorbent for a primary absorber column which provides advantageous operation.