Abstract: Ethylene is an extremely important chemical raw material, in order to cope with the problem of shutdown of 0.24 Mt/a steam cracking unit in PetroChina Lanzhou Petrochemical Company, to ensure the balance of naphtha processing of the whole plant and maintain the crude oil processing capacity of the refinery, the company has carried out the overall process scheme research for the integration of reducing oil products and increasing chemicals, make full use of the existing crude oil resources and equipment resources of the refinery, combined with the product needs of regions and enterprises, and select different process technology routes and processes. A comparative study was carried out on the transformation scheme of diesel hydrogenation unit or the new vacuum gas oil hydrocracking scheme of the refinery, and the appropriate process was explored to improve the supply of ethylene raw materials in the refinery system, reduce the output of oil products, and realize the production of 1.20 Mt/a ethylene raw materials in the refinery system of the company.

Key words: chemicals production in refinery, ethylene, overall process optimization