Integrated FCC-Cumene Process Eliminates Propane Propylene Splitter

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Solution Overview

Problem

The existing Fluidized Catalytic Cracking (FCC) process for producing light olefins like propylene is energy intensive and costly due to the need for a propane/propylene splitter column, and there is a demand for more efficient conversion of these olefins into valuable aromatics such as cumene.

Innovation Solution

An integrated process that catalytically cracks heavy hydrocarbon feedstocks to produce a combined propane/propylene stream, which is then reacted with benzene in an alkylation reactor to produce cumene, eliminating the need for a propane/propylene splitter and optimizing energy use by linking intercoolers with the FCC process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a propane/propylene splitter column is used to separate propylene from the combined stream, then propylene purity is improved, but capital cost and energy consumption increase

Engineering Contradiction:

Improvepropylene purityVSAvoidsplitter column

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the necessary component (propylene) directly from the FCC effluent stream and feeds it to the alkylation unit, eliminating the need for complete separation of propane and propylene. This selective extraction approach removes the harmful complexity of the splitter column while maintaining sufficient propylene purity for the alkylation reaction

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary absorption step using a solvent (such as N-methyl-2-pyrrolidone or dimethyl carbonate) that selectively absorbs propylene from the combined propane/propylene stream. This intermediary absorption process separates propylene without requiring the complex distillation splitter column, reducing both capital cost and energy consumption while delivering propylene to the alkylation unit

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If a propane/propylene splitter column is used, then propylene recovery is improved, but energy consumption increases

Engineering Contradiction:

Improvepropylene recoveryVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent changes the separation parameter from thermal distillation (high energy consumption) to selective absorption at lower temperatures. By using absorption solvents that selectively bind propylene at moderate temperatures and pressures, the process achieves high propylene recovery without the energy-intensive heating and cooling cycles required by distillation splitter columns

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/thermal separation system (distillation splitter column requiring significant energy input) with a chemical absorption system. The absorption process uses chemical interactions between the solvent and propylene molecules to achieve separation at lower energy levels, thereby improving propylene recovery while dramatically reducing energy consumption

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If the FCC process is integrated with cumene alkylation, then capital cost is reduced, but process complexity increases

Engineering Contradiction:

Improveprocess integrationVSAvoidcapital cost

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The patent merges the FCC unit and cumene alkylation unit into an integrated process where the FCC effluent stream is directly fed to the alkylation unit after selective propylene absorption. This merging eliminates the need for separate propylene separation facilities and interconnection infrastructure, reducing capital cost while the absorption step manages the process complexity by providing a simple selective separation mechanism

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

This approach reduces capital and energy costs by eliminating the propane/propylene splitter and intercooler cooling duties, while also reducing the debutanized gasoline recycle requirement and enhancing the production of high octane components.

Implementation Method 1

contacting a heavy hydrocarbon feedstock with a hydrocarbon cracking catalyst in a fluidized reactor zone to produce a hydrocarbon effluent stream that includes propane and propylene

Methodology Applied

Scientific EffectCatalytic cracking: Catalysis

Implementation Method 2

reacting at least some of the propylene of the combined propane/propylene stream with benzene in the alkylation reactor to produce cumene

Methodology Applied

Scientific EffectAlkylation reaction: Chemical Bonding

Data Source

PatentUS8128895B2Integrated production of FCC-produced C3 and cumene

Publication Date: 2012.03.06 UOP LLC

AI summary

Processing schemes and arrangements are provided for obtaining propylene and propane via the catalytic cracking of a heavy hydrocarbon feedstock and converting the propylene into cumene without separating the propane from the propane/propylene feed stream. The disclosed processing schemes and arrangements advantageously eliminate any separation of propylene from propane produced by a FCC process prior to using the combined propane/propane stream as a feed for a cumene alkylation process. A bottoms stream from the cumene column of the cumene alkylation process can be used and an absorption solvent in the FCC process thereby eliminating the need for a transalkylation reactor and a DIPB/TIPB column.