A device for recovering variable low-temperature gas, comprising at least a low temperature stabilizing system, a compression system, an expansion refrigeration system, and a heat exchange system, which are connected to each other by pipelines, wherein the low temperature stabilizing system is composed of a liquid storage unit, a liquid delivery unit, and a liquid jet gasification mixing unit, for regulating the temperature of low-temperature gas;
- a liquid outlet channel of the liquid storage unit is connected to a liquid inlet channel of the liquid delivery unit, a liquid outlet channel of the liquid delivery unit is connected to a liquid inlet channel of the liquid jet gasification mixing unit, and the compression system is composed of a raw material compressor and a circulating compressor, which can be used for compressing room temperature gas;
- a gas outlet channel of the raw material compressor is connected to a gas inlet channel of the circulating compressor, and the expansion refrigeration system is composed of at least one booster expansion turbine to provide cooling capacity for the device;
- a booster end and a cooler are arranged in the booster expansion turbine, the booster end and the cooler are connected in series, an outlet of the circulating compressor is connected to an inlet channel of the booster end of the expansion turbine in the expansion refrigeration system, and an outlet channel of the booster end of the expansion turbine is connected to the heat exchange system;
- the heat exchange system is composed of at least one heat exchanger and a gas-liquid separator for cold recovery of low-temperature gas and heat exchange of gas liquefaction, and the outlet channel of the booster end of the expansion turbine of the expansion refrigeration system is connected to a first inlet channel and a second inlet channel of the heat exchanger of the heat exchange system;
- an inlet channel of an expansion end of the booster expansion turbine is connected to a first outlet channel of the heat exchanger, a first inlet channel of the gas-liquid separator of the heat exchange system is connected to a second outlet channel of the heat exchanger through a pipeline and a first throttle valve, a second inlet channel of the gas-liquid separator is connected to an outlet channel of the expansion end of the booster expansion turbine, a first outlet channel of the gas-liquid separator is connected to a third inlet channel of the heat exchanger, a third outlet channel of the heat exchanger is connected to an inlet of the circulating compressor, and a second outlet channel of the gas-liquid separator is used for outputting a liquid product to the liquid storage unit;
- a first inlet channel of a liquid self-subcooler of the heat exchange system is connected to the second outlet channel of the gas-liquid separator, a first outlet channel of the liquid self-subcooler is connected to a second inlet of the liquid self-subcooler through a pipeline and a second throttle valve, a second outlet of the liquid self-subcooler is connected to a fourth inlet channel of the heat exchanger, a fourth outlet channel of the heat exchanger is connected to an inlet channel of the raw material compressor, a fifth inlet of the heat exchanger is connected to a constant low-temperature gas outlet of the liquid jet gasification mixing unit, and a fifth outlet channel of the heat exchanger is connected to the inlet channel of the raw material compressor;
- the liquid jet gasification mixing unit comprises at least one liquid nozzle, a gasification mixing chamber, a first temperature sensor, and a second temperature sensor, a gas inlet of the liquid jet gasification mixing unit is used for receiving variable low-temperature gas, a liquid inlet channel of the liquid jet gasification mixing unit is connected to the liquid nozzle, the first temperature sensor is located at an upper middle part of the gasification mixing chamber, the second temperature sensor is located at a lower part of the gasification mixing chamber, and a baffle is mounted at an outlet of the gasification mixing chamber at the liquid nozzle to increase the uniformity of the variable low-temperature gas entering the gasification mixing chamber.