Method for preparing ethylene in propylene preparation process using propane dehydrogenation reaction

A method for preparing ethylene in a propylene preparation process using a propane dehydrogenation process, the method comprising the steps of:

• passing a reactant stream containing methane, ethane, and ethylene, which are by-products generated in a de-ethanizer in a propane dehydrogenation process, through a demethanizer, thereby preferentially separating the methane;
• separating the ethane from the ethylene by passing the reactant stream, from which the methane has been separated, through an ethane/ethylene splitter;
• converting the ethane to ethylene by additionally allowing the separated ethane to react in an ethane reactor;
• passing the reactant stream, which has passed through the ethane reactor, through a quenching tower, thereby cooling the reactant stream;
• neutralizing the cooled reactant stream by passing it through a scrubber;
• and introducing the neutralized reactant stream in front of a compressor and recycling it to the dehydrogenation process;
• wherein the ethylene is recovered in the step of separating the ethane from the ethylene and the step of converting the ethane to the ethylene.