Abstract: Faced with the problems of insufficient isobutane and lack of alkylation oil in the initial srart-up of alkylation plant by sulphuric acid catalysis, the danger of “runaway temperature” will occur according to the traditional start-up standard. The simulation and sensitivity analysis of the reaction process were carried out by Aspen Plus software. The results showed that the maximum reaction temperature was 17 ℃ when the starting material contained 12.7% C4 olefin component. Therefore, a new start-up method of using n-butane to replace part of isobutane and all alkylated oil was put forward, which greatly reduced the requirements for start-up isobutane and alkylated oil, and a new “five step method” scheme for the initial start-up of the unit was established, making the initial start-up of the plant successful. The application results indicated that the new method was safe, reliable and stable, and had has a guiding significance for the initial start-up of alkylation units under non-standard conditions.

Key words: sulfuric acid method, alkylation, initial start-up, chemical simulation