Anti-freezing LNG (Liquefied Natural Gas) heat exchange method and anti-freezing LNG heat exchange device

The invention discloses an anti-freezing LNG (Liquefied Natural Gas) heat exchange method and an anti-freezing LNG heat exchange device. The device is a U-shaped tubular heat exchanger and is characterized by comprising a U-shaped tube, a sleeve, a tube tank, a longitudinal baffle, a pass partition and a shell, wherein the U-shaped tube consists of an LNG gasification section and an NG heating section; the LNG gasification section is of a sleeve structure; the NG heating section is of a single-tube structure; the interior of the tube is provided with a low-temperature gaseous natural gas passage; an intermediate coolant is a C3C4 mixture; the C3C4 mixture is used for continuously performing gas-liquid phase change circulation so as to realize an efficient indirect heat exchange process between LNG and a common heat exchange medium. The heat exchange device disclosed by the invention is compact in structure, low in cost, high in heat exchange efficiency and safe and stable in operation, and can be used for effectively solving the problem of freezing blockage generated during heat exchange of the common heat exchange medium and LNG; by virtue of self boiling and condensation of the C3C4 mixture, automatic circulative flowing of the C3C4 mixture is realized and extra power equipment is not needed, so that the equipment cost and the energy consumption are reduced, and the application prospect is favorable.