Hydrogen-Olefin Separation with Isentropic Expansion and Rectification

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Solution Overview

Problem

Existing processes for separating hydrogen from olefin hydrocarbon vapor streams in dehydrogenation units are inefficient and lack comprehensive steps to effectively isolate hydrogen, leading to suboptimal separation and purification.

Innovation Solution

A multi-step process involving cooling, separation, isentropic expansion, compression, and rectification in a system with heat exchangers and expanders/compressors, which includes cooling a compressed effluent vapor stream, separating hydrogen and olefin components, isentropically expanding and compressing the vapor streams, and further purifying the hydrogen-rich gas in a rectifier.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a simple separation process is used, then the process complexity is reduced, but the hydrogen separation purity and efficiency deteriorate

Engineering Contradiction:

Improveprocess complexityVSAvoidhydrogen separation purity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The separation process is divided into multiple sequential stages: initial cooling and separation, isentropic expansion, warming, second separation, and rectification. Each stage targets specific components at different temperature and pressure conditions, achieving high purity through progressive refinement rather than a single complex step.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The effluent stream undergoes preliminary cooling and separation before the main hydrogen extraction. This preliminary action removes heavy paraffinic components and prepares the stream for more efficient hydrogen separation in subsequent stages, preventing contamination from the outset.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If multiple separation stages are implemented, then the hydrogen separation purity is improved, but the energy consumption increases

Engineering Contradiction:

Improvehydrogen separation purityVSAvoidenergy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The isentropic expansion step utilizes the pressure energy of the compressed effluent stream to perform useful work, converting high-pressure energy into cooling effect and mechanical work. This converts what would be wasted pressure energy into a beneficial cooling step that enables separation without requiring external refrigeration.

Inventive Principle:

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

Solution Approach 2:

The system uses its own compressed effluent stream to provide the cooling necessary for separation through isentropic expansion. The high-pressure stream expands to drive the cooling process, making the system self-sufficient for its thermal requirements without external energy input for refrigeration.

Inventive Principle:

Principle #25Self-service

3Temperature

If isentropic expansion is used, then the temperature and pressure are reduced for better separation, but the process complexity increases

Engineering Contradiction:

Improveeffluent temperatureVSAvoidprocess complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The isentropic expansion induces a phase transition effect where the high-pressure gas expands and cools rapidly, changing its thermal state without requiring external cooling. This phase change-like behavior enables temperature reduction and condensation of heavy components, facilitating separation through natural thermodynamic behavior rather than mechanical cooling systems.

Inventive Principle:

Principle #36Phase transitions

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 process enhances the efficiency and effectiveness of hydrogen separation, achieving high purity hydrogen gas while optimizing energy recovery and reducing operational complexity.

Implementation Method 1

cooling a compressed effluent vapor stream in a heat exchanger

Methodology Applied

Scientific EffectHeat transfer: Heat Exchanger

Implementation Method 2

isentropically expanding, in a high-pressure expander, the second vapor stream, wherein the pressure and temperature of the second vapor stream are lowered

Methodology Applied

Scientific EffectIsentropic expansion: Adiabatic Cooling

Implementation Method 3

compressing, in a high-pressure compressor, the second vapor stream

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 4

isentropically expanding, in a low-pressure expander, the split stream, wherein the pressure and temperature of the split stream are lowered

Methodology Applied

Scientific EffectIsentropic expansion: Adiabatic Cooling

Implementation Method 5

compressing, in a low-pressure compressor, the split stream

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 6

combining the hydrogen-rich gas and the second liquid stream in the rectifier, further purifying the hydrogen-rich gas

Methodology Applied

Scientific EffectDistillation: Distillation

Data Source

PatentUS12111104B2Process for separating hydrogen from an olefin hydrocarbon effluent vapor stream

Publication Date: 2024.10.08 ENFLEX INC

AI summary

One or more specific embodiments disclosed herein includes a method for separating hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream, employing a integrated heat exchanger, multiple gas-liquid separators, external refrigeration systems, and a rectifier attached to a liquid product drum.