An apparatus for supplying additives into a coker drum includes an inlet for supplying a hydrocarbon feed stream into the coker drum and conduits along the circumference of walls of the coker drum. Each conduit has an injection nozzle to supply additives inside the coker drum. An injection control system controls the operation of the injection nozzles such that 1) one or more of the injection nozzles placed within a first distance above a vapour liquid interphase of the hydrocarbon feed stream are configured to supply the additives; and 2) supply of the additive discontinues from a particular injection nozzle when a distance between the injection nozzle and the vapour liquid interphase is less than or equal to a second distance. The apparatus optionally includes a mechanical drive system moving at least one of the conduits based on the level of the vapour liquid interphase in the coker drum.