Method for producing ethylene
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Solution Overview
Problem
The separation of ethylene and ethane from process gases produced by oxidative dehydrogenation of ethane is inefficient due to low methane content, leading to high product and educt losses in conventional separation processes, which are not suitable for process gases from steam crackers.
Innovation Solution
A process combining low-temperature separation with pressure swing adsorption to separate ethane and ethylene from lower-boiling compounds, where the process gas is cooled to specific temperature levels to condense and separate fractions, and the gaseous first fraction is subjected to pressure swing adsorption to recover ethane and ethylene efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional separation processes are used for process gases from oxidative dehydrogenation, then the separation can be performed with standard equipment, but product and educt losses are high due to low methane content
Solution Approach 1:
The patent changes the temperature parameter by cooling the process gas to cryogenic temperatures (below -100°C) to enable effective separation. This temperature change allows the process gas to be treated similarly to steam cracker gases, enabling the use of conventional separation equipment while significantly reducing product and educt losses through efficient condensation and rectification
Solution Approach 2:
The patent makes the separation process universal by adapting it to handle both steam cracker process gases and oxidative dehydrogenation process gases using the same equipment and methodology. The cryogenic separation system is designed to universally process different types of process gases by controlling temperature and pressure parameters
2Manufacturing precision
If the process gas is cooled to low temperatures for condensation, then lower-boiling compounds are effectively separated, but energy consumption increases
Solution Approach 1:
The patent converts the harmful effect of low methane content (which causes poor separation efficiency in conventional processes) into a benefit by using cryogenic temperatures. The low temperature enables effective condensation and separation of ethylene and ethane despite the low methane content, turning a process disadvantage into a separation advantage
Solution Approach 2:
The patent employs periodic action through pressure swing adsorption after the cryogenic separation. The cyclic pressurization and depressurization of the adsorption beds enables efficient recovery of any remaining ethylene and ethane from the gaseous fraction, improving overall separation efficiency without requiring continuous high energy input for cooling
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 reduces ethane and ethylene content in the gaseous first fraction, allowing for their efficient recovery and recycling, thereby increasing the overall process efficiency and reducing thermal losses.
Implementation Method 1
the separating insert is cooled and one or more condensates are separated from the separating insert
Implementation Method 2
the gaseous first fraction is subjected to a pressure swing adsorption, by means of which a third fraction containing predominantly or exclusively ethane and ethylene and a fourth fraction containing predominantly or exclusively the lower-boiling compounds than ethane and ethylene are formed
Implementation Method 3
the condensates are subjected at least in part to a low-temperature rectification to obtain a gaseous first fraction and a liquid second fraction
Data Source
Figure 1~2
Figure 3~4
AI summary
A process for the production of ethylene is proposed, wherein a process gas is formed by means of a dehydrogenation of ethane, which contains at least ethane, ethylene and compounds boiling at lower temperatures than ethane and ethylene, and wherein a separation element is formed using at least a part of the process gas and is subjected to a low-temperature separation (6), in which the separation element is cooled and in which one or more condensates are separated from the separation element, wherein the condensate(s) are at least partially subjected to a low-temperature rectification to obtain a gaseous first fraction and a liquid second fraction, wherein the gaseous first fraction contains at least the ethane and the ethylene in a lower proportion than in the separation element and the compounds boiling at lower temperatures than ethane and ethylene in a higher proportion than in the separation element.It is provided that the first fraction is subjected at least partially to pressure swing adsorption (7), by means of which a third fraction containing predominantly or exclusively ethylene and ethane and a fourth fraction containing predominantly or exclusively methane and carbon monoxide are formed. A corresponding apparatus (100) is also part of the present invention.