Polyolefin device exhaust gas recovery system and process coupling waste heat power generation and low-temperature cold energy recovery

The invention discloses a polyolefin device exhaust gas recovery system and process coupling waste heat power generation and low-temperature cold energy recovery, and belongs to the field of air pollution abatement, the system comprises a subzero treatment unit for receiving exhaust gas from a process production device, providing a heat exchange temperature difference below-100 DEG C through refrigeration gas turbine expansion, and recycling the exhaust gas from the process production device; cooling and liquefying the exhaust gas step by step, and recovering hydrocarbon substances in the exhaust gas; the waste heat utilization unit receives the low-pressure refrigeration gas from the subzero treatment unit, compresses the low-pressure refrigeration gas, cools the low-pressure refrigeration gas, constructs pressure circulation of compression and expansion and then enters a heat exchanger for circulation expansion for cooling, and a power source of a compressor can be provided by adopting waste heat power gene