A method for energy recuperation in the expansion of processed natural gas before the delivery of the latter to an acetylene production plant, comprising the steps: a) delivery of the processed natural gas from a processed natural gas supply line with a temperature of -10°C to 50°C and a pressure of 30 bar to 70 bar to a first heating stage and heating of the processed natural gas in the first heating stage to a temperature of 20°C to 40°C, b) delivery of the processed natural gas heated in the first heating stage to a second heating stage and heating of the processed natural gas in the second heating stage to a temperature of 70°C to 140°C, c) delivery of the processed natural gas heated in the second heating stage to an expansion device and expansion of the processed natural gas in the expansion device to a pressure of 2 bar to 8 bar, the expansion device being a piston expansion machine which is operated by the expansion of the processed natural gas and which generates energy, and the expansion of the processed natural gas in step c) being characterized by: c1) expansion of the processed natural gas, heated in the second heating stage, in a first expansion stage of the piston expansion machine to a pressure of 15 bar to 25 bar, the processed natural gas having a temperature of 15°C to 25°C after the expansion in the first expansion stage, c2) heating of the processed natural gas, expanded in the first expansion stage, in a third heating stage to a temperature of 70°C to 140°C, and c3) expansion of the heated processed natural gas in a second expansion stage of the piston expansion machine to a pressure of 2 bar to 8 bar, the processed natural gas having a temperature of 10°C to 100°C after the expansion in the second expansion stage, and d) delivery of the processed natural gas expanded in the piston expansion machine to a pressure of 2 bar to 8 bar to a fourth heating stage and heating of the processed natural gas in the fourth heating stage to a temperature of 40°C to 100°C before the processed natural gas is delivered to the acetylene production plant. a) delivery of the processed natural gas from a processed natural gas supply line with a temperature of -10°C to 50°C and a pressure of 30 bar to 70 bar to a first heating stage and heating of the processed natural gas in the first heating stage to a temperature of 20°C to 40°C, b) delivery of the processed natural gas heated in the first heating stage to a second heating stage and heating of the processed natural gas in the second heating stage to a temperature of 70°C to 140°C, c) delivery of the processed natural gas heated in the second heating stage to an expansion device and expansion of the processed natural gas in the expansion device to a pressure of 2 bar to 8 bar, the expansion device being a piston expansion machine which is operated by the expansion of the processed natural gas and which generates energy, and the expansion of the processed natural gas in step c) being characterized by: c1) expansion of the processed natural gas, heated in the second heating stage, in a first expansion stage of the piston expansion machine to a pressure of 15 bar to 25 bar, the processed natural gas having a temperature of 15°C to 25°C after the expansion in the first expansion stage, c2) heating of the processed natural gas, expanded in the first expansion stage, in a third heating stage to a temperature of 70°C to 140°C, and c3) expansion of the heated processed natural gas in a second expansion stage of the piston expansion machine to a pressure of 2 bar to 8 bar, the processed natural gas having a temperature of 10°C to 100°C after the expansion in the second expansion stage, and c1) expansion of the processed natural gas, heated in the second heating stage, in a first expansion stage of the piston expansion machine to a pressure of 15 bar to 25 bar, the processed natural gas having a temperature of 15°C to 25°C after the expansion in the first expansion stage, c2) heating of the processed natural gas, expanded in the first expansion stage, in a third heating stage to a temperature of 70°C to 140°C, and c3) expansion of the heated processed natural gas in a second expansion stage of the piston expansion machine to a pressure of 2 bar to 8 bar, the processed natural gas having a temperature of 10°C to 100°C after the expansion in the second expansion stage, and d) delivery of the processed natural gas expanded in the piston expansion machine to a pressure of 2 bar to 8 bar to a fourth heating stage and heating of the processed natural gas in the fourth heating stage to a temperature of 40°C to 100°C before the processed natural gas is delivered to the acetylene production plant.