Device and method for recovery and reliquefaction of boil-off gas of liquefied natural gas

The invention relates to a device for the recovery and reliquefaction of boil-off gas of liquefied natural gas, which comprises a storage tank with a safety valve and a low-temperature pump, wherein a first interface is formed between the storage tank and the safety valve and is connected with a recovery pipe; the low-temperature pump is provided with a second interface; the other end of the recovery pipe is communicated with a recovery compressor; an outlet of the recovery compressor is connected with a cooler, an oil-gas separator and a boil-off gas distributor, and first boil-off gas and second boil-off gas are respectively discharged from the boil-off gas distributor; the first boil-off gas is communicated with a screw expansion machine and enters a heat exchanger and a second screw compressor; the second boil-off gas is connected with the second interface of the low-temperature pump by the heat exchanger, a throttling valve and a gas-liquid separator; and the liquefied natural gas enters the storage tank