Parallel Riser Reaction Zone for Propylene Production

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Solution Overview

Problem

The catalytic cracking process for heavy hydrocarbon feeds faces challenges in efficiently converting light cuts and maintaining thermal balance, leading to issues with propylene production and reactor efficiency, particularly in controlling gas circulation and preventing thermal degradation of effluents.

Innovation Solution

A reaction zone comprising a principal riser for cracking heavy cuts and one or more additional risers for cracking light cuts, where the gaseous and solid effluents from the additional risers are integrated into the dilute phase of the principal reactor, allowing for controlled temperature and residence time, and eliminating the need for steam flushing, thereby optimizing propylene production and reactor performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single reactor is used for both heavy cut and light cut cracking, then device complexity is reduced, but manufacturing precision of propylene production is compromised

Engineering Contradiction:

Improvereactor configurationVSAvoidpropylene production control

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The system divides the cracking process into two separate risers: a principal riser for heavy cut cracking and an additional riser for light cut cracking. This segmentation allows each riser to be optimized for its specific function, with the additional riser operating at higher severity to maximize propylene production while the principal riser handles the heavier feedstock.

Inventive Principle:

Principle #1Segmentation

2Reliability

If steam flushing is used to eliminate dead zones in the dilute phase zone, then reliability of gas circulation is improved, but loss of energy increases

Engineering Contradiction:

Improvegas circulation controlVSAvoidsteam consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The effluents from the additional riser, which operates at higher severity and produces hot gas, are redirected into the dilute phase zone of the principal reactor. This hot gas automatically flushes the dead zones and maintains circulation without requiring external steam injection, making the system self-sufficient for this function.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If the quench for light cut conversion is used separately, then temperature control precision is improved, but device complexity increases

Engineering Contradiction:

Improvetemperature controlVSAvoidquench system configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The quench system is merged into a common configuration where a single quench injection point serves both the principal riser and the additional riser. The quench effluents are redirected into the dilute phase zone, providing temperature control for both cracking operations simultaneously, thereby reducing device complexity while maintaining control precision.

Inventive Principle:

Principle #5Merging (Combining)

4Productivity

If additional risers operating at higher severity are added for light cut cracking, then productivity of propylene production is improved, but device complexity increases

Engineering Contradiction:

Improvepropylene production quantityVSAvoidriser configuration

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The additional riser is designed as a multi-functional unit that not only cracks light cuts at higher severity to produce propylene but also serves as an additional source of hot gas to flush the dilute phase zone of the principal reactor. This universality allows the system to achieve higher propylene productivity without proportionally increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 enhances propylene production, improves catalyst circulation, and maintains efficient thermal balance, reducing thermal degradation and the need for steam flushing, while allowing for controlled temperature and residence time in the reactor.

Implementation Method 1

one or more additional risers (210) operating at higher severity than the principal riser (10) and carrying out catalytic cracking of light cuts

Methodology Applied

Scientific EffectCatalytic cracking: Catalysis

Implementation Method 2

the gaseous and solid effluents from the additional riser or risers (210) being sent to the dilute zone (110) of the principal reactor (100)

Methodology Applied

Scientific EffectGas flow and convection: Convection

Data Source

PatentUS8491781B2Reaction zone comprising two risers in parallel and a common gas-solid separation zone, for the production of propylene

Publication Date: 2013.07.23 IFP ENERGIES NOUVELLES

AI summary

The present invention describes a reaction zone comprising at least two fluidized reactors, a principal reactor for cracking a heavy hydrocarbon cut, the other, additional, reactor for cracking one or more light cuts, the effluents from the two reactors being treated in a common gas-solid separation and quench zone. Performance is enhanced because the thermal degradation reactions in the reaction zone are controlled in an optimum manner.