gas transfer membrane for ammonia removal of condensed flue gas
POLITECNICO DI MILANO Milan, Italy KUNGLIGA TEKNISKA HÖGSKOLAN Stockholm, Sweden
Andrea Cilona
GAS TRANSFER MEMBRANE FOR AMMONIA REMOVAL OF CONDENSED FLUE GAS
Supervisors: Eng. Samuel Nilsson Prof. Francesca Malpei Prof. Erik Levlin
March 2009
1
© Andrea Cilona 2009 Master Thesis Department of Land and Water Resources Engineering Royal Institute of Technology (KTH) SE-100 44 STOCKHOLM, Sweden Department of Environmental and Land Planning Engineering – DIIAR section Politecnico di Milano IT-20100 MILAN, Italy
2
ACKOWLEDGMENTS The entire project has been carried out during an internship which took place at IVL (Swedish Environment Research Centre) in Stockholm and at E.ON Combined Heat and Power Plant in Norrköping (Sweden). The first person that I’d like to thank is Eng. Samuel Nilsson because he offered me the opportunity to develop such an interesting project and he has advised and helped me in my work. I’m also grateful to all the people who participate in this project and devoted time to me: Jan Kastensson and Erkki Lathi (Mercatus Engineering AB), Uwe Fortkamp, Östen Ekengren and Rune Bergström (IVL), Mikael Norell (E.ON Örebro), Martin Ulbricht (Liqui-Cel), Per Ronnestam (Elmacron). I appreciate also the efforts of my supervisors Prof. Francesca Malpei (Politecnico di Milano) and Prof. Erik Levlin (KTH). Special thanks to my parents Annamaria and Domenico and my sister Carola: without their support and love would have been impossible to live such an experience and to realize myself in this work. Thanks also to Teresa, who stands the distance and me in the last two years. I’m also grate to Clara Corti (Studesk 2) that gave me the opportunity to work in her office and to leave one more time after my Erasmus experience in Denmark. Thank you to all the people and above all friends that I’ve met during this experience full of life...I’ll never forget you!!!
3
ABSTRACT The removal of ammonia and ammonium (whose chemical equilibrium in water is strictly controlled by the solution pH and temperature) from a liquid stream is conventionally realized through the application of physical-chemical treatment units (such as stripping, chlorination to the break-point, struvite precipitation) or biological ones (such as classic bio-nitrification and biodenitrification or the innovative nitrite stopped bio-nitrification and ANAMMOX). The study case of the E.ON Combined Heat and Power (CHP) plant in Norrköping forecasts the ammonia removal from the Condensed Flue Gas (CFG). The compound presence is due to the ammonia and urea injection in a SNCR system to reduce the NOx. In similar applications (like E.ON CHP plant in Örebro) the used technology is represented by the stripper, which exploit a hot gas stream and allows the recovery of this stripping fluid rich in ammonia, through the injection into the boiler as secondary air. The stripper application in E.ON power plant is quite difficult, due to spatial problems and to the complex CFG line configuration. The master thesis has the main target to study and test the Gas Transfer Membrane (GTM) to remove ammonia from the CFG. This technology has been applied with different configurations in other fields (degasation and mainly
O2 or
CO2
removal
from water,
carbonation,
corrosion
control,
debubbling,
nitrogenation,…): about ammonia removal it is quite new and the only application case has been in Wuppertal (Germany) but the power plant has been closed. The heart of the technology is represented by a micro-porous hydrophobic membrane which allows the dissolve gas to cross it and avoids the water passage. The GTM contactor configuration used is represented by the Direct Contact Membrane: the compound is removed by a liquid stripping fluid (sulphuric acid solution) and the driving force is the concentration gradient between the two membrane sides. The system output consists of an ammonium sulphate solution, which in theory can be recovered and injected into the boiler to decrease the corrosive power of the flue gas (above all when biomasses are fired), and to reduce NOx. Actually its qualitative and quantitative characteristics are unknown and they should be analyzed and compared to a product used for the same purpose: Chlorout by Vattenfall R&D (patent 2005). After the first step of bibliographic research about the topic, the GTM has been tested for two months (November and December 2008) directly on the field (E.ON Norrköping). The pilot plant used for the experimental work has been assembled by Mercatus Enginnering AB and forecasts the presence of “2,5 x 8 Extra Flow Product Contactor” by Liqui-Cel (whose dimensions are really compact: approximately 6 cm diameter, 30 cm length) and of gas sensing electrode to measure ammonia. The adopted pilot plant configuration consists of batch feeding and total recirculation after the GTM contactor: the continuous flow mode presented some technical problems because of the
4
gas sensing electrode fragility and of the outlet ammonia concentration increasing after few minutes of the tests. The GTM performances have been quantified by evaluating the ammonia removal efficiency for different boundary conditions. The variation parameters have been: residence time, CFG pH, temperature, flow velocity, applied pressure and initial ammonia concentration and stripping fluid pH, flow velocity and applied pressure. In Tab.1 all the parameters, their influence levels on the GTM performances and the suggested values are listed. Tab. 1 - Parameters influence and suggested set up Number
Parameter
Influence
1 2 3 4 5 6 7 8 9
Residence time (pilot plant configuration) Condensed Flue Gas pH Condensed Flue Gas temperature Condensed Flue Gas flow velocity Condensed Flue Gas applied pressure Initial ammonia concentration in the Condensed Flue Gas Sulphuric Acid solution (stripping fluid) pH Sulphuric Acid solution (stripping fluid) flow velocity Sulphuric Acid solution (stripping fluid) applied pressure
High High High Medium Low High High Low Low
Optimal Unit Range 360 min 11 > 35 °C > 200 l/h 200 ppm 2 100 - 150 l/h
Andrea Cilona
GAS TRANSFER MEMBRANE FOR AMMONIA REMOVAL OF CONDENSED FLUE GAS
Supervisors: Eng. Samuel Nilsson Prof. Francesca Malpei Prof. Erik Levlin
March 2009
1
© Andrea Cilona 2009 Master Thesis Department of Land and Water Resources Engineering Royal Institute of Technology (KTH) SE-100 44 STOCKHOLM, Sweden Department of Environmental and Land Planning Engineering – DIIAR section Politecnico di Milano IT-20100 MILAN, Italy
2
ACKOWLEDGMENTS The entire project has been carried out during an internship which took place at IVL (Swedish Environment Research Centre) in Stockholm and at E.ON Combined Heat and Power Plant in Norrköping (Sweden). The first person that I’d like to thank is Eng. Samuel Nilsson because he offered me the opportunity to develop such an interesting project and he has advised and helped me in my work. I’m also grateful to all the people who participate in this project and devoted time to me: Jan Kastensson and Erkki Lathi (Mercatus Engineering AB), Uwe Fortkamp, Östen Ekengren and Rune Bergström (IVL), Mikael Norell (E.ON Örebro), Martin Ulbricht (Liqui-Cel), Per Ronnestam (Elmacron). I appreciate also the efforts of my supervisors Prof. Francesca Malpei (Politecnico di Milano) and Prof. Erik Levlin (KTH). Special thanks to my parents Annamaria and Domenico and my sister Carola: without their support and love would have been impossible to live such an experience and to realize myself in this work. Thanks also to Teresa, who stands the distance and me in the last two years. I’m also grate to Clara Corti (Studesk 2) that gave me the opportunity to work in her office and to leave one more time after my Erasmus experience in Denmark. Thank you to all the people and above all friends that I’ve met during this experience full of life...I’ll never forget you!!!
3
ABSTRACT The removal of ammonia and ammonium (whose chemical equilibrium in water is strictly controlled by the solution pH and temperature) from a liquid stream is conventionally realized through the application of physical-chemical treatment units (such as stripping, chlorination to the break-point, struvite precipitation) or biological ones (such as classic bio-nitrification and biodenitrification or the innovative nitrite stopped bio-nitrification and ANAMMOX). The study case of the E.ON Combined Heat and Power (CHP) plant in Norrköping forecasts the ammonia removal from the Condensed Flue Gas (CFG). The compound presence is due to the ammonia and urea injection in a SNCR system to reduce the NOx. In similar applications (like E.ON CHP plant in Örebro) the used technology is represented by the stripper, which exploit a hot gas stream and allows the recovery of this stripping fluid rich in ammonia, through the injection into the boiler as secondary air. The stripper application in E.ON power plant is quite difficult, due to spatial problems and to the complex CFG line configuration. The master thesis has the main target to study and test the Gas Transfer Membrane (GTM) to remove ammonia from the CFG. This technology has been applied with different configurations in other fields (degasation and mainly
O2 or
CO2
removal
from water,
carbonation,
corrosion
control,
debubbling,
nitrogenation,…): about ammonia removal it is quite new and the only application case has been in Wuppertal (Germany) but the power plant has been closed. The heart of the technology is represented by a micro-porous hydrophobic membrane which allows the dissolve gas to cross it and avoids the water passage. The GTM contactor configuration used is represented by the Direct Contact Membrane: the compound is removed by a liquid stripping fluid (sulphuric acid solution) and the driving force is the concentration gradient between the two membrane sides. The system output consists of an ammonium sulphate solution, which in theory can be recovered and injected into the boiler to decrease the corrosive power of the flue gas (above all when biomasses are fired), and to reduce NOx. Actually its qualitative and quantitative characteristics are unknown and they should be analyzed and compared to a product used for the same purpose: Chlorout by Vattenfall R&D (patent 2005). After the first step of bibliographic research about the topic, the GTM has been tested for two months (November and December 2008) directly on the field (E.ON Norrköping). The pilot plant used for the experimental work has been assembled by Mercatus Enginnering AB and forecasts the presence of “2,5 x 8 Extra Flow Product Contactor” by Liqui-Cel (whose dimensions are really compact: approximately 6 cm diameter, 30 cm length) and of gas sensing electrode to measure ammonia. The adopted pilot plant configuration consists of batch feeding and total recirculation after the GTM contactor: the continuous flow mode presented some technical problems because of the
4
gas sensing electrode fragility and of the outlet ammonia concentration increasing after few minutes of the tests. The GTM performances have been quantified by evaluating the ammonia removal efficiency for different boundary conditions. The variation parameters have been: residence time, CFG pH, temperature, flow velocity, applied pressure and initial ammonia concentration and stripping fluid pH, flow velocity and applied pressure. In Tab.1 all the parameters, their influence levels on the GTM performances and the suggested values are listed. Tab. 1 - Parameters influence and suggested set up Number
Parameter
Influence
1 2 3 4 5 6 7 8 9
Residence time (pilot plant configuration) Condensed Flue Gas pH Condensed Flue Gas temperature Condensed Flue Gas flow velocity Condensed Flue Gas applied pressure Initial ammonia concentration in the Condensed Flue Gas Sulphuric Acid solution (stripping fluid) pH Sulphuric Acid solution (stripping fluid) flow velocity Sulphuric Acid solution (stripping fluid) applied pressure
High High High Medium Low High High Low Low
Optimal Unit Range 360 min 11 > 35 °C > 200 l/h 200 ppm 2 100 - 150 l/h
