Riser Mixing Chamber for Catalyst Temperature Uniformity

Solution Overview

Problem

Existing processes for mixing carbonized and regenerated catalysts in fluid catalytic cracking (FCC) often result in uneven temperature distribution, leading to non-selective cracking and reduced product value due to inadequate mixing before contacting hydrocarbon feeds.

Innovation Solution

A process and apparatus that utilize a chamber in the lower section of the reactor riser to thoroughly mix carbonized and regenerated catalyst streams by feeding them through separate conduits, ensuring a more homogeneous temperature before they contact the hydrocarbon feed, using a chamber within the riser to facilitate mixing by fluidizing gas and angular motion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a large mixing chamber is used to thoroughly mix carbonized and regenerated catalyst streams, then mixing uniformity is improved, but capital cost and catalyst inventory requirements increase

Engineering Contradiction:

Improvemixing uniformityVSAvoidcapital cost

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The mixing process is segmented into two distinct zones: a first region where hot regenerated catalyst is introduced, and a second region where cold carbonized catalyst is introduced. This spatial segmentation allows thorough mixing without requiring a large single chamber, as mixing occurs progressively through the segmented zones rather than in one large volume.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mixing chamber is nested within the reactor riser structure, utilizing the existing riser volume for mixing purposes. The chamber is positioned inside the riser such that the mixing process occurs within the overall reactor footprint, eliminating the need for separate external mixing vessels and reducing capital cost.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Stability of the object's composition

If a large mixing chamber is used to thoroughly mix carbonized and regenerated catalyst streams, then mixing uniformity is improved, but catalyst inventory requirements increase

Engineering Contradiction:

Improvemixing uniformityVSAvoidcatalyst inventory

Core Design Contradiction:

Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

The mixing process is segmented into two distinct zones: a first region where hot regenerated catalyst is introduced, and a second region where cold carbonized catalyst is introduced. This spatial segmentation allows thorough mixing without requiring a large single chamber, as mixing occurs progressively through the segmented zones rather than in one large volume.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mixing chamber is nested within the reactor riser structure, utilizing the existing riser volume for mixing purposes. The chamber is positioned inside the riser such that the mixing process occurs within the overall reactor footprint, eliminating the need for separate external mixing vessels and reducing catalyst inventory requirements.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Temperature

If catalyst streams are mixed before contacting hydrocarbon feed, then temperature uniformity is improved, but inadequate mixing leads to hot spots and non-selective cracking

Engineering Contradiction:

Improvetemperature uniformityVSAvoidproduct value

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The mixing process is segmented into two distinct zones: a first region where hot regenerated catalyst is introduced, and a second region where cold carbonized catalyst is introduced. This spatial segmentation allows thorough mixing without requiring a large single chamber, as mixing occurs progressively through the segmented zones rather than in one large volume.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The catalyst streams are pre-mixed in the mixing chamber before they contact the hydrocarbon feed. This preliminary mixing action ensures temperature uniformity is achieved prior to the cracking reaction, preventing hot spots and non-selective cracking that would otherwise occur during feed contact.

Inventive Principle:

Principle #10Preliminary action

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 ensures a more uniform temperature distribution among the catalyst streams, reducing the occurrence of hot spots and non-selective cracking, thereby enhancing the quality and value of the product hydrocarbons by ensuring thorough mixing of catalysts before they interact with the feed.

Implementation Method 1

using a chamber within the riser to facilitate mixing by fluidizing gas and angular motion

Methodology Applied

Scientific EffectFluidisation: Fluidisation

Implementation Method 2

using a chamber within the riser to facilitate mixing by fluidizing gas and angular motion

Methodology Applied

Scientific EffectAngular motion: Angular Momentum

Data Source

PatentUS8747758B2Process and apparatus for mixing two streams of catalyst

Publication Date: 2014.06.10 UOP LLC

AI summary

A process and apparatus for mixing streams of regenerated and carbonized catalyst involves passing a catalyst stream into and out of a chamber in a lower section of a riser. The chamber fosters mixing of the catalyst streams to reduce their temperature differential before contacting hydrocarbon feed.