CO2 Extraction Plants

CO2 Extraction Plants

♦The plant is based on CO2 recovery from an external flue gas source.

♦The flue gas is cooled in a flue gas scrubber where a sodalye is recirculated in order to wash out sulphur dioxide. An exhauster leads the flue gas from the flue gas scrubber to the absorber. In the absorber the CO2 in the flue gas is absorbed in a 30% MEA  lye and inhibitor solution. A washing section in the top of the absorber removes retained MEA, which is then returned to the absorber. The gas residue is exhausted to the atmosphere.

♦The CO2 rich MEA lye is preheated in the rich/lean lye heat exchanger, before being pumped to the stripper,where further heating in the reboiler releases the entrapped CO2 MEA vapour, steam and CO2 leaving the reboiler flows upwards in the stripper and enters a washing section in the top of the stripper where retained MEA vapour is removed.

♦Steam and CO2 leaves the stripper and enters the reflux condenser where they are cooled before entering the reflux drum. In the reflux drum CO2 is separated from the condensate. Condensate is lead back to the stripper. The stripped MEA lye from the reboiler is led from the stripper bottom through the rich/lean lye heat exchanger and the MEA lye cooler back to the absorber. A side-stream carbon filter removes organic compounds from the cold MEA lye. Other contaminants in the MEA lye such as heat stable salts and other chain compounds are periodically removed by boiling in a reclaimer.

♦The CO2 gas from the reflux drum is cooled in a gas cooler and condensate is removed in a water trap. The CO2 gas is further cleaned in a potassium permanganate scrubber before being compressed to 16 bar by means of a two stage compressor.

♦To allow condensation the CO2 gas is dried in a dehydrator to a dew point of abt -60℃. The dehydrator is electrically heated and automatically regenerated by inert gas from the CO2 condenser and thereby acts as a purging system for  non-condensable gases.

♦The CO2 is then passed through a carbon filter for removal of odours.

♦The purified and dried gas is condensed in a multi-tube heat exchanger at a temperature of about -30℃. The matching refrigeration plant is equipped with an ammonia or freon compressor. The refrigeration plant maintains the correct operating pressure in the CO2 condenser.

♦The liquid deep-cooled CO2 is led to an insulated storage tank.