INTERMEDIATE FLUID TYPE VAPORIZER

An intermediate fluid type vaporizer includes: an intermediate medium evaporator including a heat transfer tube through which seawater flows, and configured to evaporate at least a part of an intermediate medium in the form of a liquid on the outside of the heat transfer tube by heat exchange between the seawater and the intermediate medium; and an LNG evaporator including a heat transfer tube through which LNG flows, and configured to vaporize the LNG flowing through the heat transfer tube by condensing the intermediate medium evaporated in the intermediate medium evaporator on the outside of the heat transfer tube. The heat transfer tube is made of titanium or a titanium alloy. The outer circumferential surface of the heat transfer tube is formed with grooves having cavities for communicating with the outside via gaps formed in the outer surface of the heat transfer tube.