Flow Transition Pipe Geometry for Stable Pneumatic Conveying

Solution Overview

Problem

Pneumatic conveyance systems in gasification processes often experience unstable flow patterns due to plug flows, leading to overheating issues, as the solid feed discharged from vessels tends to form high concentration and low concentration parts, which are extremely unstable, necessitating a transition to a stable flow pattern.

Innovation Solution

A flow pattern transition pipe with a first expansion section increasing in diameter, followed by a shrink section and a third section with a smaller identical diameter, designed to reduce superficial velocity and change the flow pattern from plug flow to uniform flow, ensuring carrier gas velocities are below saltation and above pick-up velocities, respectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If solid feed is discharged from a feed vessel in pneumatic conveyance systems, then conveyance capability is achieved, but the flow pattern becomes unstable due to plug flows with high and low concentration parts

Engineering Contradiction:

Improveconveyance capabilityVSAvoidconveyance stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The transition pipe is divided into three distinct sections: a first expansion section (L1) that reduces carrier gas velocity and promotes particle deposition, a second shrink section (L2) that increases velocity and picks up particles, and a third pipe section that maintains stable uniform flow. This segmentation allows different flow transformation functions in each section, converting unstable plug flow into stable uniform flow while maintaining conveyance capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes key flow parameters by controlling carrier gas velocity through geometric transformations. The expansion section reduces velocity below saltation velocity to enable particle deposition, while the shrink section increases velocity above pick-up velocity to re-entrain particles uniformly. These parameter changes transform the flow pattern from unstable plug flow to stable uniform flow.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If an expansion section is added to reduce carrier gas velocity below saltation velocity, then flow pattern stability is improved, but the device complexity increases

Engineering Contradiction:

Improveflow pattern stabilityVSAvoidpipe structure complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The transition pipe is divided into three distinct sections: a first expansion section (L1) that reduces carrier gas velocity and promotes particle deposition, a second shrink section (L2) that increases velocity and picks up particles, and a third pipe section that maintains stable uniform flow. This segmentation allows different flow transformation functions in each section, converting unstable plug flow into stable uniform flow while maintaining conveyance capability.

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If the axial length of the first section is made 3 to 5 times the second section, then flow pattern transition effectiveness is improved, but the length of the transition pipe increases

Engineering Contradiction:

Improveflow pattern transition effectivenessVSAvoidtransition pipe length

Core Design Contradiction:

Stability of the object's compositionVSLength of moving object

Solution Approach 1:

The invention changes key flow parameters by controlling carrier gas velocity through geometric transformations. The expansion section reduces velocity below saltation velocity to enable particle deposition, while the shrink section increases velocity above pick-up velocity to re-entrain particles uniformly. These parameter changes transform the flow pattern from unstable plug flow to stable uniform flow.

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

The transition pipe effectively stabilizes the flow pattern, reducing fluctuations to less than 10%, transforming unstable plug flows into stable uniform flows, enhancing conveyance stability and preventing overheating in gasifiers.

Implementation Method 1

a carrier gas velocity at the maximum inner diameter end of the first section lower than a saltation velocity

Methodology Applied

Scientific EffectSaltation: Saltation (geology)

Implementation Method 2

a carrier gas velocity at the minimum inner diameter end of the second section higher than a pick-up velocity

Methodology Applied

Scientific EffectPick-up velocity:

Data Source

PatentUS20120318394A1Flow pattern transition pipe

Publication Date: 2012.12.20 AIR PROD & CHEM INC

AI summary

A flow pattern transition pipe for use in a pneumatic conveyance system is provided. The flow pattern transition pipe comprises a first expansion pipe section gradually increasing in inner diameter in an axial direction, a second shrink pipe section following the first section from a maximum inner diameter end of the first section and gradually reducing in inner diameter in an axial direction away from the first section, and a third pipe section following the second section from a minimum inner diameter end of the second section, with a substantially identical inner diameter smaller than a minimum inner diameter of the first section. An axial length of the first section is from about three to about five times of the axial length of the second section.