Composite refrigerant refrigerated light secondary-dealkylation hydrocarbon recovering device

The utility model discloses a composite refrigerant refrigerated light secondary-dealkylation hydrocarbon recovering device, which is combined with the advantage of conventional direct heat exchange process of dealkylation of natural gas. Precooling of the natural gas, condensing of overhead gas of a deethanization tower, recovering of refrigerating capacity of natural gas products and liquid-phase materials of a lower-temperature separator are realized in a main heat exchange, and sources of refrigerating capacity during dealkylation are provided by a composite refrigerant refrigerating system. Dried natural gas is dealkylated primarily in the low-temperature separator and contacts with condensate on the top of the deethanization tower in a reflux manner in a secondary-dealkylation tower so that secondary dealkylation is completed, and accordingly, yield rate of C3 is increased, and benefits of the composite refrigerant refrigerated light secondary-dealkylation hydrocarbon recovering device are increased. In addition, the composite refrigerant refrigerated light secondary-dealkylation hydrocarbon recovering device has the advantages of low energy consumption, high C3 yield rate and high adaptability to variations of working conditions, and the like.