PROCESS AND PLANT FOR MANUFACTURING CEMENT IN THE OXYFUEL MODE
Process for operating a cement or lime plant comprising a cement or lime kiln and a calciner, wherein heat is generated by combustion of a fuel in the kiln and/or calciner, wherein a gas fed to the kiln and the calciner or to the calciner for combustion of the fuel contains an oxygen rich exhaust gas from a bioreactor containing photoautotrophic organisms and wherein the plant is preferably operated in the oxyfuel mode by using exhaust gas from the kiln and/or calciner together with the oxygen from the bioreactor as the gas fed to the kiln and/or calciner for combustion of the fuel.
1 . A process for operating a cement or lime plant comprising a cement or lime kiln ( 1 , 11 , 21 , 31 ) and a calciner ( 2 , 12 ) in case of a cement plant, wherein heat is generated by combustion of a fuel in the kiln ( 1 , 11 , 21 , 31 ) and/or in the calciner ( 2 , 12 ), wherein a gas fed to the kiln ( 1 , 11 , 21 , 31 ) and the calciner ( 2 , 12 ) or to the calciner ( 2 , 12 ) for combustion of the fuel contains an oxygen rich exhaust gas from a bioreactor ( 4 , 14 , 24 , 34 ) containing photoautotrophic organisms.
2 . The process according to claim 1 , wherein an exhaust gas from the kiln ( 1 , 21 ) and/or calciner ( 2 ) is partly recycled into the kiln ( 1 , 21 ) and/or calciner ( 2 ), operating the kiln ( 1 , 21 ) and/or calciner ( 2 ) in the oxyfuel mode.
3 . The process according to claim 2 , wherein the gas fed to the the kiln ( 1 , 21 ) and the calciner ( 2 , 12 ) or to the calciner ( 2 , 12 ) consists of the recycled exhaust gas from the kiln ( 1 , 21 ) and/or calciner ( 2 , 12 ) and the oxygen rich exhaust gas from the bioreactor ( 4 , 14 , 24 ).
4 . The process according to claim 2 , wherein the exhaust gas from the kiln ( 1 , 11 , 21 , 31 ) and/or calciner ( 2 , 12 ) that is not recycled into the kiln ( 1 , 11 , 21 , 31 ) and/or calciner ( 2 , 12 ) is passed into the bioreactor ( 4 , 14 , 24 , 34 ) as feed gas for the photoautotrophic organisms.
5 . The process according to claim 1 , wherein the generated oxygen is partly stored during a time when the bioreactor ( 4 , 24 ) generates oxygen and stored oxygen is fed to the kiln ( 1 , 21 ) and/or calciner ( 2 ) during a time when the bioreactor ( 4 , 24 ) does not generate oxygen.
6 . The process according to claim 2 , wherein the gas from the kiln ( 1 , 21 ) and/or calciner ( 2 ) that is not recycled into the kiln ( 1 , 21 ) and/or calciner ( 2 ), the vented gas, is stored during a time when the bioreactor ( 4 , 24 ) does not generate oxygen and stored gas is fed to the bioreactor ( 4 , 24 ) during a time when the bioreactor ( 4 , 24 ) generates oxygen.
7 . The process according to claim 1 , wherein the exhaust gas from the kiln ( 11 , 31 ) and/or calciner ( 12 ) is not recycled into the kiln ( 11 , 31 ) or the calciner ( 12 ) and is passed into the bioreactor ( 14 , 34 ) as feed gas for the photoautotrophic organisms.
8 . The process according to claim 7 , comprising the further step of enriching the exhaust gas in CO 2 prior to passing it into the bioreactor ( 14 , 34 ).
9 . A cement or lime plant comprising a cement or lime kiln ( 1 , 11 , 21 , 31 ), in the case of a cement plant a calciner ( 2 , 12 ), and at least one burner for generating heat by combustion of a fuel in the kiln ( 1 , 11 , 21 , 31 ) and/or in the calciner ( 2 , 12 ), wherein it further comprises a bioreactor ( 4 , 14 , 24 , 34 ) containing photoautotrophic organisms and means for passing oxygen generated by the organisms into the kiln ( 1 , 11 , 21 , 31 ) and/or calciner ( 2 , 12 ).
10 . The cement or lime plant according to claim 9 , wherein the cement or lime kiln ( 1 , 11 , 21 , 31 ) and/or calciner ( 2 , 12 ) is an oxyfuel kiln ( 1 , 21 ) and/or oxyfuel calciner ( 2 ) receiving exhaust gas from the kiln ( 11 , 21 ) and/or calciner ( 2 ) and the oxygen generated by the organisms as gas for the combustion of the fuel.
11 . The cement or lime plant according to claim 10 , further comprising devices for liquefying ( 5 , 7 ) oxygen and exhaust gas from the kiln ( 1 , 21 ) and/or calciner ( 2 ) that is not recycled into the kiln ( 1 , 21 ) and/or calciner ( 2 ), the vented gas, containers ( 6 , 8 ) for storing the liquefied oxygen and the vented gas, and devices for evaporating the stored oxygen and vented gas and feeding the oxygen into the kiln ( 1 , 21 ) and/or calciner ( 2 ) and the vented gas into the bioreactor ( 4 , 24 ), respectively.
12 . Use of oxygen enriched exhaust gas from a bioreactor ( 4 , 14 , 24 , 34 ) containing photoautotrophic organisms as full or partial replacement of air for combustion of a fuel in a kiln ( 1 , 11 ) and/or a calciner ( 2 , 12 ) of a cement plant or in a kiln ( 21 , 31 ) of a lime plant.