Used 17,500 TPD Selective Hydrogenation Unit built in 2000. Process removes sulfur from cracked naphtha with minimal loss of octane, minimum hydrogen consumption and no RVP increase. The SHU reaction converts light sulfur molecules to heavier molecules prior to separation of the light, low sulphur fraction. In this particular unit the SHU reactions are: 1) Selective hydrogenation of diolefins to avoid gum formation in SHDS reactors, and 2) Conversation or light mercaptans and sulphides into heavier sulphur molecules while minimising olefin saturation. The design treat gas ratio is 15 m3 of H2 per m3 of hydrocarbon feed, with a reactor pressure of 23.5 barg, and temperatures of 160°C (start of run) to 200°C (end of run).