High cyclic capacity amines for high efficiency co2 scrubbing processes (ExxonMobil)

CATEGORY: CARBON CAPTURE 
High cyclic capacity amines for high efficiency co2 scrubbing processes (ExxonMobil)

Type	Patent
Inventor	Pavel Kortunov
Inventor	Michael Siskin
URL	Free Full Text Source:  http://www.google.com/patents/US20140030177
Assignee	Exxonmobil Research And Engineering Company
Patent Number	US20140030177 A1
Issue Date	Jan 30, 2014
Abstract	A high cyclic capacity carbon dioxide scrubbing process contacts a gas stream containing carbon dioxide in a sorption zone with a liquid scrubbing solution of a low molecular weight sterically hindered amine, particularly a secondary alkanolamine or aminoether at a high concentration, typically at least 3.5M and at a temperature of at least 30° C. to sorb the carbon dioxide into the solution and form a rich stream of the sorbed carbon dioxide in the solution in the form of dissolved amine carbamate and/or alkanolamine bicarbonate. The rich stream is then passed from the sorption zone to at least one regeneration zone and the sorbed carbon dioxide is desorbed as gas from the solution to form a lean solution containing a reduced concentration of sorbed carbon dioxide relative to the rich stream; the lean stream is then returned to the sorption zone for a further sorption cycle. FIELD OF THE INVENTION This invention relates to the removal of carbon dioxide and other acid gases from a gaseous stream containing one or more of these gases. In particular, the invention relates to a method for separating an acid gas, e.g., carbon dioxide, from a gas mixture using one or more secondary amines as the sorbent. BACKGROUND OF THE INVENTION The removal of carbon dioxide from mixed gas streams is of great industrial importance and commercial value. Carbon dioxide is a ubiquitous and inescapable by-product of the combustion of hydrocarbons and there is growing concern over its accumulation in the atmosphere and its potential role in global climate change. Laws and regulations driven by environmental factors may therefore soon be expected to require its capture and sequestration. While existing methods of CO2 capture have been satisfactory for the scale in which they have so far been used, future uses on the far larger scale required for significant reductions in atmospheric CO2 emissions from major stationary combustion sources, such as power stations fired by fossil fuels, makes it necessary to improve the energy efficiency of the processes used for the removal of CO2 from gas mixtures and thereby lower the cost of CO2 capture. According to data developed by the Intergovernmental Panel on Climate Change, power generation produces approximately 78% of stationary source emissions of CO2 with other industries such as cement production (7%), refineries (6%), iron and steel manufacture (5%), petrochemicals (3%), oil and gas processing (0.4%) and the biomass industry (bioethanol and bioenergy) (1%) making up the bulk of the total, illustrating the very large differences in scale between power generation on the one hand and all other uses on the other. To this must be added the individual problem of the sheer volumes of gas which will need to be treated. Flue gases generally consist mainly of nitrogen from combustion air, with the CO2, nitrogen oxides, and other emissions such as sulfur oxides making up relatively smaller proportions of the gases which require treatment.