With Pentair Union Engineering's Carbon Capture Plants , CO2 can be captured from any gas stream with a CO2 content of up to 30 % for example coming from the combustion of coal or heavy fuel oil-fired steam boilers, and natural gas-fired combustion engines.
The AAT Capture Plants from Union Engineering are based on the most proven absorption technology currently available on the market: High concentrated monoethanolamine (MEA). MEA is a primary amine that reacts readily with carbon dioxide.
Once the carbon dioxide is captured in the MEA solution, it is transferred to a stripping system. Here, the CO2 is again released from the MEA solution by increasing the temperature to a point where the chemical reaction that took place in the absorber is reversed.
Having started as a gas with a low concentration of carbon dioxide, the gas being released from the stripper is now a highly concentrated stream containing roughly 99.9 % pure carbon dioxide. This stream can either be used directly in gaseous form or be further purified and liquefied to meet the strictest requirements.
The purification column is the final purification step, consisting of a distillation column, which enables separation/blow-off of non-condensable gasses, reducing the O2 content in the final product to max 5 ppm (v/v) and obtaining CO2 purity of min. 99.999 % (v/v).
The electrical system for the AAT Carbon Capture Plant assures:
The plant is designed for high efficiency and reliability through components selected for 24/7 operation.
The plant is based on the extraction of CO2 from an existing flue gas source resulting in significant operational savings compared to traditional CO2 Generation Plants. Basically, any available flue gas source can be used. The MEA solvent is continuously purified through a unique system allowing for a high O2 feed gas content that would result in excessive solvent degradation and plant corrosion in other installations. Inhibitors are not needed and the solvent used constitutes a 35 w/w % MEA solution, which is a non-proprietary component, easily available on the merchant market.
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 by means of a chemical reaction with Sodium Hydroxide (NaOH). The NaOH 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 pressurized and heated in a heat exchanger and then led to the NOxFlash column. Here most of the contaminants like O2, N2 and NO are removed from the rich MEA solution by flashing to the absorber pressure.
A heating stream of pure CO2 is added to the bottom of the NOxFlash column for further reduction of the contaminants in the MEA solution. This optimizes the process yield to the best possible CO2 product without any use of expensive chemicals (Pentair Union Engineering Patent).
Then the rich MEA solution is pumped to a stripper, where the CO2 is released from the MEA solution by means of heat added to a reboiler. Typically, the heat comes from an external steam source, but if the flue gas is hot, it may be possible to utilize this heat as well. 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.
Before liquefaction, the gas is dried to a dew point of below -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 odor 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 99.999% (v/v) and fulfils quality standards as a food/beverage ingredient as specified by International Society of Beverage Technologists (ISBT) and European Industrial Gases Association (EIGA).
Advanced Amine Technology plant traditional sizes (measured as liquid food-grade CO2 produced): 500 - 4500 kg/h
Other capacities are available upon request.
|Union Engineering Advanced Amine Technology - AAT|
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