Regenerator Annulus Filling for Shell Temperature Control

Solution Overview

Problem

In catalytic cracking regenerators, insufficient heat transfer across the annulus between the internal riser and outer shell can lead to condensation of sulfuric acid, causing corrosion due to temperature differences, especially when processing high sulfur feeds.

Innovation Solution

Filling the annular trough below the primary seal with a material having a heat transfer coefficient of at least that of air to enhance heat transfer from the riser to the shell, preventing sulfuric acid condensation by maintaining the shell temperature above the dew point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If insulation is installed in the annulus to prevent catalyst entry and mitigate heat transfer, then catalyst protection is improved, but heat transfer from riser to shell deteriorates causing sulfuric acid condensation

Engineering Contradiction:

Improvecatalyst entry into annulusVSAvoidshell temperature

Core Design Contradiction:

Object-affected harmful factorsVSTemperature

Solution Approach 1:

The annulus is divided into two functional zones: an upper zone with insulation for catalyst protection and heat mitigation, and a lower zone with high heat transfer coefficient material for thermal management. This segmentation allows each zone to perform its specific function optimally without interfering with the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different materials with different heat transfer properties are placed in different locations within the annulus. The upper annulus contains insulation material for catalyst protection, while the lower annulus contains material with heat transfer coefficient at least as high as air for thermal management, creating local quality variations that address different requirements at different locations.

Inventive Principle:

Principle #3Local quality

2Temperature

If material with high heat transfer coefficient is used in the annulus, then heat transfer from riser to shell is improved, but catalyst protection and heat mitigation deteriorate

Engineering Contradiction:

Improveheat transfer from riser to shellVSAvoidheat transfer to shell

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The annulus is divided into two functional zones: an upper zone with insulation for catalyst protection and heat mitigation, and a lower zone with high heat transfer coefficient material for thermal management. This segmentation allows each zone to perform its specific function optimally without interfering with the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different materials with different heat transfer properties are placed in different locations within the annulus. The upper annulus contains insulation material for catalyst protection, while the lower annulus contains material with heat transfer coefficient at least as high as air for thermal management, creating local quality variations that address different requirements at different locations.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If the annulus is left empty to accommodate thermal expansion, then flexibility for thermal stresses is improved, but heat transfer control and sulfuric acid condensation prevention deteriorate

Engineering Contradiction:

Improveflexibility for thermal stressesVSAvoidsulfuric acid condensation

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The heat transfer coefficient parameter of the annulus filling material is specifically selected to be at least as high as that of air. This parameter change ensures sufficient heat transfer from the riser to the shell to maintain shell temperature above the sulfuric acid dew point, preventing condensation while the annulus structure accommodates thermal expansion.

Inventive Principle:

Principle #35Parameter changes

4Object-affected harmful factors

If insulation material is used to maintain shell temperature, then sulfuric acid condensation is prevented, but device complexity and installation difficulty increase

Engineering Contradiction:

Improvesulfuric acid condensationVSAvoidannulus filling structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The heat transfer coefficient parameter of the annulus filling material is specifically selected to be at least as high as that of air. This parameter change ensures sufficient heat transfer from the riser to the shell to maintain shell temperature above the sulfuric acid dew point, preventing condensation while the annulus structure accommodates thermal expansion.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively prevents sulfuric acid condensation and corrosion by ensuring the outer shell temperature remains above the dew point, thereby extending the lifespan of the regenerator components.

Implementation Method 1

The material with a higher heat transfer coefficient will transfer more heat from the hotter riser to the shell to ensure the shell temperature is sufficiently above the sulfuric acid dew point

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

A heat transfer coefficient characterizes the ability to transfer heat across a medium by conduction, convection and radiation

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS10576443B1Sealing apparatus for a catalyst regenerator

Publication Date: 2020.03.03 UOP LLC

AI summary

A regenerator for an FCC apparatus. The regenerator includes an internal riser inside of a outer shell. The internal riser includes a cone and a cone skirt. An annulus is formed between the internal riser and the outer shell. A sealing apparatus for keeping catalyst out of a portion of the annulus comprises a first sealing element and a second sealing element disposed above the first sealing element. An annular trough in the annulus below the primary seal is filled with material that has a heat transfer coefficient at least as high as air to allow heat to get to the inner surface of the outer shell.