A process for steam cracking a whole crude including a volatilization step performed to maintain a relatively large hydrocarbon droplet size. The process may include contacting a whole crude with steam to volatilize a portion of the hydrocarbons, wherein the contacting of the hydrocarbon feedstock and steam is conducted at an initial relative velocity of less than 30 m/s, for example. The resulting vapor phase, including volatilized hydrocarbons and steam may then be separated from a liquid phase comprising unvaporized hydrocarbons. The hydrocarbons in the vapor phase may then be forwarded to a steam pyrolysis reactor for steam cracking of the hydrocarbons in the vapor phase.