Two-Stage Heat Exchanger for CO2 Sublimation Without Plugging

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Solution Overview

Problem

Traditional natural gas liquefaction processes face challenges with carbon dioxide solidification, leading to equipment plugging and fouling due to the high freezing temperature of carbon dioxide relative to methane, which requires costly pre-cleanup and inefficient sublimation in standard heat exchangers.

Innovation Solution

A system comprising a first heat exchanger for vaporizing a fluid containing solid particles and a second heat exchanger for sublimating these particles, where the vaporization chamber maintains the solid particles in a suspended state and the sublimation chamber uses a cone-shaped design to prevent melting and fouling, allowing for continuous processing without plugging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard heat exchangers are used to sublime carbon dioxide, then the sublimation process can occur, but the solid carbon dioxide will settle and plug the piping and ports

Engineering Contradiction:

Improvecontinuous operation without pluggingVSAvoidsolid particle settling and plugging

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The heat exchanger is divided into multiple sections with progressively larger internal diameters along the flow direction. This segmentation allows the slurry to flow smoothly through each section without the solid carbon dioxide particles settling and plugging the narrower sections, enabling continuous operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the geometric dimension of the heat exchanger by implementing a diverging cross-sectional area design. Instead of maintaining a constant diameter, the internal diameter increases in the direction of fluid flow, providing additional spatial dimension for particle suspension and preventing settling.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If the carbon dioxide is removed prior to liquefaction, then the liquefaction process can proceed without solidification problems, but the filtration equipment becomes large, energy-intensive, and expensive

Engineering Contradiction:

Improveliquefaction process continuityVSAvoidfiltration equipment size and cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts the carbon dioxide removal function from the traditional pre-cleanup filtration stage and integrates it into the liquefaction process itself. The carbon dioxide is allowed to solidify during cooling and is then removed in the heat exchanger through sublimation, eliminating the need for separate large-scale filtration equipment.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention converts the harmful effect of carbon dioxide solidification (which causes plugging in traditional systems) into a beneficial feature. By designing the heat exchanger with increasing internal diameter, the solid carbon dioxide particles are accommodated and subsequently sublimated, transforming a problem into a manageable part of the process.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of operation

If the heat exchanger internal diameter is increased to prevent plugging, then solid particles can pass through more easily, but the heat transfer efficiency decreases

Engineering Contradiction:

Improvesolid particle flow through heat exchangerVSAvoidheat transfer efficiency

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The heat exchanger is segmented into multiple sections, each with optimized dimensions. The internal diameter increases progressively from one section to the next, allowing solid particles to pass through earlier sections more easily while maintaining sufficient heat transfer surface area. This segmentation balances particle flow requirements with heat transfer efficiency.

Inventive Principle:

Principle #1Segmentation

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 enables efficient vaporization and sublimation of carbon dioxide without fouling, maintaining system efficiency and preventing plugging, thereby overcoming the limitations of traditional methods by optimizing temperature and flow conditions in separate chambers.

Implementation Method 1

a first heat exchanger configured to receive the fluid including solid particles and to vaporize the fluid

Methodology Applied

Scientific EffectVaporization: Evaporation

Implementation Method 2

a second heat exchanger configured to receive the vaporized fluid and solid particles and to sublimate the solid particles

Methodology Applied

Scientific EffectSublimation: Sublimation

Data Source

PatentUS9254448B2Sublimation systems and associated methods

Publication Date: 2016.02.09 THE UNITED STATES AS REPRESENTED BY THE DEPARTMENT OF ENERGY

AI summary

A system for vaporizing and sublimating a slurry comprising a fluid including solid particles therein. The system includes a first heat exchanger configured to receive the fluid including solid particles and vaporize the fluid and a second heat exchanger configured to receive the vaporized fluid and solid particles and sublimate the solid particles. A method for vaporizing and sublimating a fluid including solid particles therein is also disclosed. The method includes feeding the fluid including solid particles to a first heat exchanger, vaporizing the fluid, feeding the vaporized fluid and solid particles to a second heat exchanger and sublimating the solid particles. In some embodiments the fluid including solid particles is liquid natural gas or methane including solid carbon dioxide particles.