Co2 extraction plants

The plant is based on the combustion of fuel in an MEA heater equipped with a burner. After the combustion, the flue gas will have a CO₂ content of 10-14% v/v and will exit the MEA heater at a temperature of approximately 250°C.

The flue gas is directed to a flue gas scrubber, in which the gas is cooled and water condensed. Any SO₂ present in the flue gas will be removed utilizing a chemical reaction with sodium carbonate (soda ash). The soda ash is automatically added to the scrubbing water through pH control.

After cooling and scrubbing, the gas is led via an exhauster through an absorber, in which the gas flows counter-current to the MEA solution flow. By chemical reaction, the MEA solution absorbs the CO₂ from the flue gas. The MEA solution containing the absorbed CO₂ (referred to as rich MEA solution) is first pressurised and heated in a heat exchanger and then led to the NOxFlash column. Here most of the contaminants are removed from the rich MEA solution by flashing to the absorber pressure.

Further heating is added to the bottom of the NOxFlash column for further reduction of the contaminants in the MEA solution. This optimises the process yield to the best possible CO₂ product without any use of expensive chemicals (Union patent pending).

Afterwards, the rich MEA solution is pumped to a stripper, where the CO₂ is released from the MEA solution using the combustion heat generated in the MEA heater. The CO₂ depleted MEA solution (referred to as lean MEA solution) is recycled to the absorber. After exiting the top of the stripper, the CO₂ rich gas is cooled in a gas cooler and washed in an after-scrubber for removal of potential MEA carry-over. The gas is then compressed in two stages to approx. 15-18 bar(g) by the CO₂ compressor.

Prior to liquefaction, the gas is dried to a dew point of approx. -60°C (10 ppm v/v H₂O) in the dehydrator. Regeneration is done automatically by electrical heating and the use of dry purge gas from the CO₂ condenser. Traces (if any) of acetaldehyde are also removed in the dehydrator. The CO₂ gas then passes through an activated carbon filter for the removal of any odour substances.

To remove the last non-condensable gases, the CO₂ gas first passes a reboiler in the purification system (type PUR-D). It is then condensed at a temperature of approx. -27°C/-21°C in a

CO₂ condenser, where the non-condensed gases are purged off. Finally, the liquefied CO₂ is led through the distillation column to an insulated storage tank.

A refrigeration unit, controlled by the CO₂ pressure in the CO₂ condenser, supplies the matching refrigeration capacity. The liquid CO₂ is stored under a pressure of approx. 15-18 bar(g) and a corresponding temperature of approx. -27°C/-21°C. During a non-CO₂ production period, the refrigeration unit can operate independently of the rest of the CO₂ plant to maintain the correct CO₂ storage tank temperature/pressure.

The CO₂ produced has a purity higher than 99.99% (v/v) and fulfils quality standards as a food/beverage ingredient.