Method for maximizing ethylene or propene production

A method for maximizing production of ethylene or propylene, characterized by comprising:

• S1, pretreating a raw material, mixing the pretreated raw material with superheated steam in a mixer, and feeding the well-mixed raw material and superheated steam into a catalytic cracking reactor, wherein the raw material is converted into waste residue and high-temperature oil and gas in the presence of a catalyst;
• obtaining light distillate oil, heavy distillate oil, a gaseous product, by cooling and purifying the high-temperature oil and gas using a two-stage prewashing column;
• wherein the two-stage prewashing column comprises a section for preheating and a section for desuperheating;
• S2, hydrogenating the heavy distillate oil in step S1, reforming alkene components in the light distillate oil and separating benzene-toluene-xylene (BTX) components in the light distillate oil as one of products;
• and
• feeding alkane components in the light distillate oil to a steam cracking device;
• S3, recycling the products formed by hydrogenating and the products formed by reforming, and the steam-cracked distillate oil obtained in step S2 to the catalytic cracking reactor in step S1, and once more carrying out a selective catalytic cracking reaction in the catalytic cracking reactor, wherein a mass ratio of a total amount of the recycled products to an amount of a fresh raw material is 10-60:100;
• and
• S4, feeding the gaseous product in step S1 to the steam cracking device, and collectively separating methane, ethane, ethylene, propane, propylene, wherein ethylene and propylene are used as the products;
• and returning the ethane, the propane, other alkanes to the steam cracking device;
• wherein by the above steps, the raw material is finally converted into the products comprising methane, the ethane, ethylene, propylene, BTX, wherein the total yield of ethylene and propylene is 45-75 m % of the raw materials, the yield of the arene BTX is 15-30 m % of the raw materials, and the majority of the remainder is methane.