Method and device for separating a carbon dioxide-containing gas by partial condensation and/or distillation and/or solidification

A process for separating a gas containing CO2, at least one air gas, NO2 and mercury, involving the following steps:

• i) compressing the gas in a turbocharger coupled to a turbine, forming a compressed gas,
• ii) heating the gas upstream or downstream of the turbocharger, the gas being heated to a temperature between 50 and 150 °C upstream of the demercurizer, and demercurization of the heated compressed gas in one or more non-regenerative mercury adsorption reactors, producing a demercurized gas,
• iii) cooling the demercurized gas,
• iv) separating the cooled gas in a unit operating at temperatures below 10 °C or even below −50 °C by partial condensation in one or more stages and/or by distillation and/or solidification, producing at least one fluid containing at least 95 mol % or even at least 99 mol % of CO2 and a pressurized stream of CO2-depleted gas and
• v) at least part of the CO2-depleted gas is expanded in the turbine coupled to the turbocharger, possibly after heating to a temperature above 10 °C.

A device configured to separate a feed gas containing CO2, at least one air gas, NO2 and mercury, the device comprising:

• a turbocharger;
• a turbine coupled to the turbocharger;
• a demercurization unit;
• a cooler;
• a heater, wherein the heater is connected to heat the feed gas upstream or downstream of the turbocharger;
• a separation unit configured to separate by partial condensation in one or more stages and/or by distillation and/or solidification operating at temperatures below 10 °C;
• means for sending the feed gas to the turbocharger;
• means for sending the compressed and heated feed gas to the demercurization unit to form a demercurized gas;
• means for sending the demercurized gas to the cooler and from the cooler to the separation unit to produce at least one fluid containing at least 95 mol % or even at least 99 mol % of CO2 and a pressurized stream of CO2-depleted gas;
• and
• means for sending at least part of the CO2-depleted gas to expand in the turbine coupled to the turbocharger.