Flue Gas Processing in Amine-Based Carbon Capture Systems
Merikoski, Riku (2012)
Merikoski, Riku
2012
Ympäristö- ja energiatekniikan koulutusohjelma
Luonnontieteiden ja ympäristötekniikan tiedekunta - Faculty of Science and Environmental Engineering
This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
Hyväksymispäivämäärä
2012-05-09
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201205221155
https://urn.fi/URN:NBN:fi:tty-201205221155
Tiivistelmä
Carbon dioxide (CO2) has been proven to have an adverse effect on world climate and its atmospheric levels are increasing at an accelerating pace. Because carbon dioxide is the most important greenhouse gas, its emission levels should be cut to slow down
climate change. A large proportion of the anthropogenic emissions of this gas are produced by power plants combusting fossil fuels. Consequently, carbon capture and storage (CCS) has been proposed as a way to cut such emissions in power plants.
Amine absorption is currently the leading carbon capture method. Amines are chemical derivatives of ammonia that are able to first absorb CO2 and then release it when heated. There are health and environmental concerns related to amines and their degradation products, so amine emissions to the environment should be minimised. This thesis thus contains recommendations for acceptable amine levels in the atmosphere.
The amine absorption process is sensitive to SOx, NOx and particulates that may, depending on the fuel, be present in the flue gas from conventional combustion. The normal emission control systems are often adequate to control the other pollutants, but SOx must be reduced to even lower levels before the absorber. This often requires additional investment. The absorber operates at fairly low temperatures, so the flue gas must also be cooled before the absorber. This increases the cooling demand of the plant.
There are two actively marketed amine absorption technologies in which commercial experience exists. One uses a simpler and less expensive solvent while the other consumes less energy and has smaller amine losses. Amines are lost in the absorption process due to amine vapourisation, amine entrainment in the flue gas and amine degradation. The two first losses occur in the absorber, so they cause amine emissions to the air. However, degradation accounts for the greatest losses because the amine reclaimer purifying the amine solution to ensure reliable operation of the process removes the degraded amines from circulation.
After absorption and subsequent desorption, the CO2 is not yet ready for transportation or storage because it must first be purified and compressed to meet the CO2 quality requirements for its further use. The requirements for ship transport are stricter than those for pipeline transport, and enhanced oil recovery by CO2 injection needs purer CO2 than storage in saline aquifers. Amine absorption produces CO2 of good quality, so usually only compression and drying are needed before it is ready for transportation and storage.
The thesis shows that it is technically possible to build and operate a large-scale CCS plant with existing amine absorption technology and thus markedly reduce emissions. However, today this is not yet economically feasible because the process consumes much energy and requires much investment.
climate change. A large proportion of the anthropogenic emissions of this gas are produced by power plants combusting fossil fuels. Consequently, carbon capture and storage (CCS) has been proposed as a way to cut such emissions in power plants.
Amine absorption is currently the leading carbon capture method. Amines are chemical derivatives of ammonia that are able to first absorb CO2 and then release it when heated. There are health and environmental concerns related to amines and their degradation products, so amine emissions to the environment should be minimised. This thesis thus contains recommendations for acceptable amine levels in the atmosphere.
The amine absorption process is sensitive to SOx, NOx and particulates that may, depending on the fuel, be present in the flue gas from conventional combustion. The normal emission control systems are often adequate to control the other pollutants, but SOx must be reduced to even lower levels before the absorber. This often requires additional investment. The absorber operates at fairly low temperatures, so the flue gas must also be cooled before the absorber. This increases the cooling demand of the plant.
There are two actively marketed amine absorption technologies in which commercial experience exists. One uses a simpler and less expensive solvent while the other consumes less energy and has smaller amine losses. Amines are lost in the absorption process due to amine vapourisation, amine entrainment in the flue gas and amine degradation. The two first losses occur in the absorber, so they cause amine emissions to the air. However, degradation accounts for the greatest losses because the amine reclaimer purifying the amine solution to ensure reliable operation of the process removes the degraded amines from circulation.
After absorption and subsequent desorption, the CO2 is not yet ready for transportation or storage because it must first be purified and compressed to meet the CO2 quality requirements for its further use. The requirements for ship transport are stricter than those for pipeline transport, and enhanced oil recovery by CO2 injection needs purer CO2 than storage in saline aquifers. Amine absorption produces CO2 of good quality, so usually only compression and drying are needed before it is ready for transportation and storage.
The thesis shows that it is technically possible to build and operate a large-scale CCS plant with existing amine absorption technology and thus markedly reduce emissions. However, today this is not yet economically feasible because the process consumes much energy and requires much investment.