Method for preparing ethylene with improved energy efficiency

A method for preparing ethylene with improved energy efficiency, comprising:

• providing a C2 compound isolated from a de-ethanizer column to an acetylene converter;
• converting acetylene of the C2 compound into ethylene and ethane;
• transferring the C2 compound containing ethylene and ethane converted from acetylene to a first C2 splitter to isolate and discharge a part of the ethylene;
• and
• transferring a lower stream containing ethane and a remaining part of the ethylene of the C2 compound, which are not discharged from the first C2 splitter, to a second C2 splitter, to isolate and discharge the remaining part of the ethylene of the C2 compound, and converting the ethane of the C2 compound into ethylene to be recycled,
• wherein a heat exchanger is installed between the de-ethanizer column and the first C2 splitter to perform direct heat exchange between the de-ethanizer column and the first C2 splitter, a difference in pressure between the de-ethanizer column and the first C2 splitter to enable the heat exchange is 4.5 kgf/cm2 G or more, and a concentration of ethylene contained in the lower stream of the first C2 splitter is 70 to 80 mol %, and
• wherein the heat exchange is performed between the lower stream of the first C2 splitter and an upper stream of the de-ethanizer column.