The Experts below are selected from a list of 1068 Experts worldwide ranked by ideXlab platform
Kelly Thambimuthu - One of the best experts on this subject based on the ideXlab platform.
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combustion characteristics of coal in a mixture of oxygen and Recycled Flue Gas
Fuel, 2006Co-Authors: Yewen Tan, Eric Croiset, Mark A Douglas, Kelly ThambimuthuAbstract:The combustion of coal in a mixture of pure O2 and Recycled Flue Gas is one variant of a novel combustion approach called oxy-fuel combustion. With the absence of N2, this approach leads to a Flue Gas stream highly enriched in CO2. For many applications, this Flue Gas stream can then be compressed and sequestered without further separation. As a result, oxy-fuel combustion is an attractive way to capture CO2 produced from fossil fuel combustion. When coal is burned in this O2 and CO2 rich environment, its combustion characteristics can be very different from conventional air-fired combustion. In CETC-O, a vertical combustor research facility has been used in the past years to investigate the combustion characteristics of several different coals with this variant of oxy-fuel combustion. This included flame stability, emissions of NOx, SOx and trace elements, heat transfer, in-furnace flame profiles and Flue Gas compositions. This paper will report some of the major findings obtained from these research activities.
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co2 capture using oxygen enhanced combustion strategies for natural Gas power plants
Fuel, 2002Co-Authors: Yewen Tan, Mark A Douglas, Kelly ThambimuthuAbstract:Abstract This paper describes a series of experiments conducted with natural Gas in air and in mixtures of oxygen and Recycled Flue Gas, termed O2/CO2 recycle combustion. The objective is to enrich the Flue Gas with CO2 to facilitate its capture and sequestration. Detailed measurements of Gas composition, flame temperature and heat flux profiles were taken inside CANMET's 0.3 MWth down-fired vertical combustor fitted with a proprietary pilot scale burner. Flue Gas composition was continuously monitored. The effects of burner operation, including swirling of secondary stream and air staging, on flame characteristics and NOx emissions were also studied. The results of this work indicate that oxy–Gas combustion techniques based on O2/CO2 combustion with Flue Gas recycle offer excellent potential for retrofit to conventional boilers for CO2 emission abatement. Other benefits of the technology include considerable reduction and even elimination of NOx emissions, improved plant efficiency due to lower Gas volume and better operational flexibility.
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nox and so2 emissions from o2 co2 recycle coal combustion
Fuel, 2001Co-Authors: Eric Croiset, Kelly ThambimuthuAbstract:Abstract Capturing CO 2 from conventional coal-fired power plant is very costly because of its relatively dilute concentration in the Flue Gas. One option to reduce the cost of Gas separation is to increase CO 2 concentration in the Flue Gas by eliminating nitrogen before combustion and by recycling part of the Flue Gas. This scheme is known as O 2 /CO 2 recycle combustion. The present work focuses on the implications of O 2 /CO 2 recycle combustion on NO x and SO 2 emissions. Two main types of experiments were performed: combustion in once-through O 2 /CO 2 mixtures and experiments with Recycled Flue Gas. Combustion in air was performed as a base case. For each experiment, NO x and SO 2 were measured at several locations along the reactor and the experimental results are presented in this paper.
Juan Adanez - One of the best experts on this subject based on the ideXlab platform.
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optimum temperature for sulphur retention in fluidised beds working under oxy fuel combustion conditions
Fuel, 2013Co-Authors: L F De Diego, A Rufas, F Garcialabiano, M De Las Obrasloscertales, Alberto Abad, P Gayan, Juan AdanezAbstract:Abstract Oxy-fuel combustion is one of the leading options for power generation with CO 2 capture. The process consists of burning the fuel with a mixture of nearly pure oxygen and a CO 2 -rich Recycled Flue Gas, resulting in a product Flue Gas from the boiler containing mainly CO 2 and H 2 O. Among the possible boiler types, fluidised bed combustors are very appropriate for the oxy-fuel process because they allow the in situ desulphurisation by feeding Ca-based sorbents into the combustor. In this work, the effect of the temperature of the combustor on the retention of the SO 2 generated in the combustion of two coals with very different sulphur content (a lignite and an anthracite) has been studied. The experimental facility used was a bubbling fluidised bed (BFB) combustor of ∼3 kW th . Tests were conducted under oxy-fuel combustion mode and also under enriched-air combustion mode for comparison reasons. A Spanish limestone “Granicarb” was used as Ca-based sorbent for sulphur retention. The temperatures tested were between 800 and 970 °C using Ca/S molar ratios between 0 and 3. It was found that in BFB combustors operating under oxy-fuel combustion conditions the optimum temperature to achieve the highest sulphur retention was 900–925 °C, whereas operating with enriched air the optimum combustion temperature was 850–870 °C. Working at the optimum temperature, the SO 2 retentions were lower in oxy-fuel combustion than in enriched air combustion conditions. It was also observed that working with lignite there was 10–15% of sulphur retention by coal ashes, however, working with anthracite the sulphur retention by coal ashes was negligible. This finding was independent of the combustion mode used, oxy-fuel or enriched air.
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effects of temperature and Flue Gas recycle on the so2 and nox emissions in an oxy fuel fluidized bed combustor
Energy Procedia, 2013Co-Authors: M De Las Obrasloscertales, L F De Diego, A Rufas, F Garcialabiano, Alberto Abad, P Gayan, Juan AdanezAbstract:Abstract Oxy-fuel combustion consists in burning a fuel with a mixture of nearly pure oxygen and a CO 2 -rich Recycled Flue Gas resulting in a product Flue Gas from the boiler containing mainly CO 2 and H 2 O. In this work, the effect of combustion temperature and Flue Gas recycle composition on pollutant emissions and on the sulfation process, in order to optimize the SO 2 retention in circulating fluidized beds (CFBC), were analyzed. The experimental work was carried out with an anthracite coal in a 3 kWth continuous bubbling fluidized bed (BFB) combustor operating in oxy-fuel conditions. It was found that in oxy-combustion conditions in BFB an increase of combustor temperature produced an increase on NO emission and a decrease in the CO and N 2 O emissions. The optimum temperature to reach the highest sulphur retention was at 900-925 °C. Flue Gas recirculation was simulated by mixing different Gases (CO 2 , SO 2 , NO, and steam) in different concentrations. It was observed that SO 2 recycle produced an increase on the sulfur retention as a consequence of the higher SO 2 concentration existing in the bed. About 65% of the Recycled NO was reduced to N 2 , being the NO converted to N 2 O lower than 5vol.%. Wet recycle produced an important reduction on NO emission in comparison with dry recycle.
Alfons Kather - One of the best experts on this subject based on the ideXlab platform.
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offGas treatment downstream the Gas processing unit of a pulverised coal fired oxyfuel power plant with polymeric membranes and pressure swing adsorption
Energy Procedia, 2013Co-Authors: Jens Dickmeis, Alfons KatherAbstract:Abstract Due to climate change it is necessary to reduce anthropogenic climate Gas emissions. The application of carbon capture and storage (CCS) technologies could be a suitable approach to lower the specific CO 2 emissions from coal-fired power plants. One of these CCS technologies is the Oxyfuel process. In the Oxyfuel process the coal is burned in a mixed atmosphere of O 2 and Recycled Flue Gas. The Flue Gas thus generated has a high CO 2 concentration, because of the missing air nitrogen. Still the dried Flue Gas consists of approximately 15 mol-% impurities (O 2 , N 2 , Ar, NO x and SO x ). To increase the CO 2 -purity the Flue Gas is treated in a Gas processing unit (GPU). Two promising technologies to perform the Gas processing are partial condensation and distillation. Both are well known and available at industrial scale. Using these technologies about 90% of the CO 2 can be separated. The remaining part of the CO 2 leaves the GPU with the offGas. To increase the overall capture rate of the CO 2 in the Oxyfuel process the offGas from the GPU can be treated in either a pressure swing adsorption (PSA) cycle or a polymeric membrane (PM) cycle. These cycles generate a CO 2 -enriched GPU-recycle stream and an exhaust Gas stream which consists of the residual impurities. The CO 2 -enriched GPU-recycle can be fed back to the GPU or mixed with the CO 2 product stream of the GPU. The exhaust Gas stream with the impurities has a high content of O 2 and could be refed to the air separation unit (ASU) to increase the efficiency of the overall process. The additional Gas treatment in the PSA- or the PM-cycle has inFluences on the specific energy demand of the GPU, the CO 2 capture rate, the composition of the CO 2 product stream and the overall process efficiency. In the work presented here the feed Gas of the GPU is the Flue Gas of a large scale bituminous coal-fired Oxyfuel power plant. The plant model is based on the actual state-of-the-art power plant technology. For the GPU two different reference process cases are modelled. One case with a distillation of the CO 2 and one case with a partial condensation of the CO 2 are considered. For both cases the GPU process is externally cooled. These reference cases are compared then with a distillation and a partial condensation which have an additional offGas treatment by PSA or PM. For the offGas treatment with membranes, polymeric membranes are considered due to their high CO 2 /O 2 -selectivity and high permeability. For the offGas treatment with PSA a multiple bed cycle is modelled to assure continuous operation of the plant. The overall CO 2 capture rate, the specific energy demand and the composition of the CO 2 product stream are calculated for the reference cases, the distillation with PSA or PM and the partial condensation with PSA or PM. With these results the potential of these technologies for the GPU shall be compared with the reference cases. Furthermore a recycle of the O 2 -containing Gas stream to the ASU is modelled in the overall process model. This Recycled Gas stream can be used to reduce the energy demand of the ASU. The inFluence of the offGas treatment is evaluated by calculating the net efficiency of the overall process.
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Flue Gas concentrations and efficiencies of a coal fired oxyfuel power plant with circulating fluidised bed combustion
Energy Procedia, 2013Co-Authors: Matthias Weng, Claas Gunther, Alfons KatherAbstract:Abstract In contrast to an Oxyfuel process with pulverised coal (PC) firing, possible advantages of a circulating fluidised bed combustion (CFBC) are the in-furnace sulphur dioxide removal no additional sulphur dioxide removal downstream the steam generator might be necessary and the feasibility for concepts with a reduced Flue Gas recirculation. In [1] design conditions for the overall process of an Oxyfuel CFBC with highest Flue Gas recirculation up to 75% are compared to concepts with less Recycled Flue Gas. Compared to [1], this work is not focussed on design aspects of the steam generator but rather on the changing structure of auxiliary power demand of an integrated overall process caused by a reduced Flue Gas recirculation. At full load operation and under realistic boundary conditions achievable efficiencies of an Oxyfuel CFBC will be examined and compared to the PC-fired Oxyfuel process.
Arto Hotta - One of the best experts on this subject based on the ideXlab platform.
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near zero co2 emissions in coal firing with oxy fuel circulating fluidized bed boiler
Chemical Engineering & Technology, 2009Co-Authors: Kari Myohanen, Timo Hyppanen, Toni Pikkarainen, Timo Eriksson, Arto HottaAbstract:Carbon capture and storage is a concept to reduce greenhouse Gas emissions of energy production from fossil fuels. In oxy-fuel combustion, the fuel is burned in a mixture of oxygen and Recycled Flue Gas. This generates CO 2 -rich Flue Gas from which the CO 2 is easily separated and compressed. Foster Wheeler Power Group is developing the existing design tools and process models of air-fired circulating fluidized bed boilers to implement specific features of oxycombustion. The validation data is produced from bench-scale and pilot-scale experiments at the VTT, Technical Research Centre of Finland. A three-dimensional circulating fluidized bed (CFB) furnace model is developed and applied by Lappeenranta University of Technology for predicting the effects of oxycombustion in full scale units. This paper presents concept studies and initial 3D modeling results based on a 460 MW e supercritical CFB power plant at Lagisza, and pilot-scale studies with Flue Gas recirculation demonstrating real oxygen combustion conditions.
Mark A Douglas - One of the best experts on this subject based on the ideXlab platform.
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combustion characteristics of coal in a mixture of oxygen and Recycled Flue Gas
Fuel, 2006Co-Authors: Yewen Tan, Eric Croiset, Mark A Douglas, Kelly ThambimuthuAbstract:The combustion of coal in a mixture of pure O2 and Recycled Flue Gas is one variant of a novel combustion approach called oxy-fuel combustion. With the absence of N2, this approach leads to a Flue Gas stream highly enriched in CO2. For many applications, this Flue Gas stream can then be compressed and sequestered without further separation. As a result, oxy-fuel combustion is an attractive way to capture CO2 produced from fossil fuel combustion. When coal is burned in this O2 and CO2 rich environment, its combustion characteristics can be very different from conventional air-fired combustion. In CETC-O, a vertical combustor research facility has been used in the past years to investigate the combustion characteristics of several different coals with this variant of oxy-fuel combustion. This included flame stability, emissions of NOx, SOx and trace elements, heat transfer, in-furnace flame profiles and Flue Gas compositions. This paper will report some of the major findings obtained from these research activities.
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techno economic study of co2 capture from an existing coal fired power plant mea scrubbing vs o2 co2 recycle combustion
Energy Conversion and Management, 2003Co-Authors: D Singh, Eric Croiset, P L Douglas, Mark A DouglasAbstract:Abstract The existing fleet of modern pulverised coal fired power plants represents an opportunity to achieve significant reductions in greenhouse Gas emissions in the coming years providing that efficient and economical CO2 capture technologies are available for retrofit. One option is to separate CO2 from the products of combustion using conventional approaches such as amine scrubbing. An emerging alternative, commonly known as O2/CO2 recycle combustion, involves burning the coal with oxygen in an atmosphere of Recycled Flue Gas. Both approaches can be retrofitted to existing units, however they consume significant amounts of energy to capture, purify and compress the CO2 for subsequent sequestration. This paper presents a techno-economic comparison of the performance of the two approaches. The comparison was developed using the commercial process simulation packages, Hysys & Aspen Plus. The results show that both processes are expensive options to capture CO2 from coal power plants, however O2/CO2 appears to be a more attractive retrofit than MEA scrubbing. The CO2 capture cost for the MEA case is USD 53/ton of CO2 avoided, which translates into 3.3 ¢/kW h. For the O2/CO2 case the CO2 capture cost is lower at USD 35/ton of CO2 avoided, which translates into 2.4 ¢/kW h. These capture costs represent an approximate increase of 20–30% in current electricity prices.
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modeling of oxy fuel combustion for a western canadian sub bituminous coal
Fuel, 2003Co-Authors: Eddy H Chui, Mark A Douglas, Yewan TanAbstract:Abstract The motivation of this research is to develop practical oxy-coal combustion techniques in order to facilitate the conversion of coal-fired utility power plants so as to recover a CO 2 rich Flue Gas stream for use and/or sequestration. The objective of this study is to ascertain the applicability and accuracy of a modeling tool to assist with future pilot scale oxy-fuel combustion experiments and burner scale-up studies. Two modes of oxy-coal combustion, O 2 enriched air (OEA) and Recycled Flue Gas (RFG), were experimentally tested in a 0.3 MW th pilot-scale combustor using a western Canadian sub-bituminous coal. The computational fluid dynamic tool was utilized to model the combustion, heat transfer and pollutant formation characteristics of these test cases and to examine the impact due to changes in the combustion medium, burner swirl and burner configuration. The model provided insights for the observed variation in NO x production among the test cases: the dramatic increase in the OEA mode, the drop at higher burner swirl settings and the surprisingly small reduction in the RFG mode. Overall the model results compared well with measured data in all test cases and established confidence in using the model to explore new design concepts for oxy-coal combustion.
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co2 capture using oxygen enhanced combustion strategies for natural Gas power plants
Fuel, 2002Co-Authors: Yewen Tan, Mark A Douglas, Kelly ThambimuthuAbstract:Abstract This paper describes a series of experiments conducted with natural Gas in air and in mixtures of oxygen and Recycled Flue Gas, termed O2/CO2 recycle combustion. The objective is to enrich the Flue Gas with CO2 to facilitate its capture and sequestration. Detailed measurements of Gas composition, flame temperature and heat flux profiles were taken inside CANMET's 0.3 MWth down-fired vertical combustor fitted with a proprietary pilot scale burner. Flue Gas composition was continuously monitored. The effects of burner operation, including swirling of secondary stream and air staging, on flame characteristics and NOx emissions were also studied. The results of this work indicate that oxy–Gas combustion techniques based on O2/CO2 combustion with Flue Gas recycle offer excellent potential for retrofit to conventional boilers for CO2 emission abatement. Other benefits of the technology include considerable reduction and even elimination of NOx emissions, improved plant efficiency due to lower Gas volume and better operational flexibility.