The present invention provides a method for revamping an HF or sulphuric acid alkylation unit to an ionic liquid alkylation unit, wherein the HF or sulphuric acid alkylation unit comprise at least: —a reactor unit for contacting catalyst and hydrocarbon reactants; —a separator unit for separating a reactor effluent into a catalyst phase and an alkylate-comprising hydrocarbon phase; —a fractionator unit for fractionating the alkylate-comprising hydrocarbon phase into at least one stream comprising alkylate; and which method includes: —providing a second separator unit suitable for the separation of solids from liquids downstream of the reactor unit suitable to reduce the solids content in at least part of the reactor effluent.