Ethane separation with cryogenic heat exchanger

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Solution Overview

Problem

Conventional cryogenic separation systems for propylene production and purification are inefficient and costly due to the need for multiple refrigeration packages and complex fractionation processes to separate hydrogen from light hydrocarbons, particularly in dehydrogenation of paraffins to olefins.

Innovation Solution

Integration of a deethanizer column with a cryogenic heat exchanger that uses a refrigerant stream for reboiling and cooling, allowing for a single refrigeration package to efficiently separate hydrogen, C2−, and C3+ hydrocarbons, reducing capital and operational expenses by eliminating the need for steam reboiling and simplifying the separation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cryogenic separation systems are used to separate hydrogen from light hydrocarbons, then separation is achieved, but multiple refrigeration packages and complex fractionation processes are required, increasing capital and operational costs

Engineering Contradiction:

Improveseparation efficiencyVSAvoidnumber of refrigeration packages

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the deethanizer column with the cryogenic heat exchanger into an integrated system where the heat exchanger serves dual functions: cooling the feed stream and providing refrigeration for the deethanizer column. This merging eliminates the need for separate refrigeration packages while maintaining effective separation of hydrogen from light hydrocarbons.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cryogenic heat exchanger is designed to perform multiple functions simultaneously: it cools the dehydrogenation reactor effluent, provides refrigeration for the deethanizer column, and enables the separation process. This multi-functionality reduces the overall number of equipment items and simplifies the process configuration.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If conventional cryogenic separation systems are used, then hydrogen separation is achieved, but the process requires steam reboiling and multiple equipment items, increasing utility usage and capital expenses

Engineering Contradiction:

Improvehydrogen purityVSAvoidcapital expenses

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The deethanizer column is merged with the cryogenic heat exchanger, eliminating the need for separate reboiler equipment and steam utility systems. The integrated design uses the refrigeration cycle itself to provide the necessary heating for the deethanizer, reducing both capital and operational expenses.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the conventional steam reboiling system with a refrigeration-based heating system. The refrigerant stream, after absorbing heat in the heat exchanger, provides the necessary thermal energy for the deethanizer column, substituting mechanical steam generation with a thermodynamic cycle integration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If multiple refrigeration packages are used for cooling and fractionation, then separation is achieved, but operational expenses increase

Engineering Contradiction:

Improvepropylene productionVSAvoidoperational expenses

Core Design Contradiction:

ProductivityVSUse of energy by stationary object

Solution Approach 1:

The patent merges the refrigeration and fractionation functions into a single integrated system. The cryogenic heat exchanger and deethanizer column work together as one unit, eliminating the need for multiple independent refrigeration packages and reducing operational expenses while maintaining propylene production capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated system allows for continuous operation where the refrigeration cycle and fractionation process work simultaneously and continuously. The heat exchanger continuously cools the feed while the deethanizer continuously separates the components, maximizing productivity while minimizing energy waste through heat integration.

Inventive Principle:

Principle #20Continuity of useful 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 enables the use of a single deethanizer column, reducing compressor stages, equipment count, and utility usage, while achieving high hydrogen purity and simplifying the separation process, thereby enhancing the economic viability of propylene production.

Implementation Method 1

cooling a deethanizer overhead line in the cryogenic heat exchanger

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 2

reboiling the deethanizer column with a refrigerant stream

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 3

cooling process streams alone to remove hydrogen from light hydrocarbon liquid

Methodology Applied

Scientific EffectCryogenic cooling: Cryogenics

Data Source

PatentUS20220316798A1Ethane separation with cryogenic heat exchanger

Publication Date: 2022.10.06 UOP LLC

AI summary

A process and apparatus integrate a deethanizer column with a cryogenic heat exchanger by reboiling the deethanizer column with a refrigerant stream and/or cooling a deethanizer overhead line in the cryogenic heat exchanger. A single stage separator and a single deethanizer column may be used to obtain high purity hydrogen in the net gas stream and an ethane rich off-gas stream, whereas conventionally a dual stage separator and two deethanizer columns were necessary for equivalent purity, respectively.