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Item type:Publication, Access status: with files , Flue gas concentrations and efficiencies of a coal-fired Oxyfuel power plant with circulating fluidised bed combustionIn 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. © 2013 The Author.Publicationtype: Conference PaperScopus© Citations 10 410 441 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Offgas treatment downstream the gas processing unit of a pulverised coal-fired Oxyfuel power plant with polymeric membranes and pressure swing adsorptionDue 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 CO2 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 O2 and recycled flue gas. The flue gas thus generated has a high CO2 concentration, because of the missing air nitrogen. Still the dried flue gas consists of approximately 15 mol-% impurities (O2, N2, Ar, NOx and SOx). To increase the CO2-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 CO2 can be separated. The remaining part of the CO 2 leaves the GPU with the offgas. To increase the overall capture rate of the CO2 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 CO2-enriched GPUrecycle stream and an exhaust gas stream which consists of the residual impurities. The CO2-enriched GPU-recycle can be fed back to the GPU or mixed with the CO2 product stream of the GPU. The exhaust gas stream with the impurities has a high content of O2 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 CO2 capture rate, the composition of the CO2 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 CO2 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 CO2/O2-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 CO2 capture rate, the specific energy demand and the composition of the CO2 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 O2-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.Publicationtype: Conference PaperScopus© Citations 6 311 335 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Restrictions and limitations for the design of a steam generator for a coal-fired Oxyfuel power plant with circulating fluidised bed combustionAs general restrictions for the design of Oxyfuel pulverised coal-fired (PC) steam generators are commonly known, the purpose of this work is to show general restrictions for the design of an Oxyfuel coal-fired steam generator using a circulating fluidised bed combustor (CFBC) with external heat exchangers (EHEs). For the CFBC restrictions result on the one hand out of the used fuels composition. On the other hand certain restrictions out of state-of-the-art and steam generator geometries have to be considered within the design.Publicationtype: Conference PaperScopus© Citations 12 303 460 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Overall process analysis and optimisation for CO₂ capture from coal fired power plants based on phase change solvents forming two liquid phases(Elsevier, 2012-11); ; ; ; In this work the potential of a novel post-combustion CO₂ capture process is analysed with respect to the integrated overall process. As solvent a blend of two amines (DEEA/MAPA) which forms two liquid phases under CO₂ loading is used. The two phases have distinct physical characteristics. Only the heavy phase, rich in CO₂ loading, is led to the desorber. The novel solvent combination promises very low energy consumption compared to a 30 wt.-% MEA solution. The efficiency penalty, taking into account the integrated overall process, is very low too. Furthermore, different integration configurations in the overall process are investigated to show the effect in greenfield and retrofit power plant cases.Publicationtype: Conference PaperScopus© Citations 62 353 334 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Evaluation and comparison of the part load behaviour of the CO₂ capture technologies oxyfuel and post-combustionThe rising share of fluctuating renewable energies increasingly demand flexible and part load operation of fossil-fuelled power plants with and without CCS. In this work the part load behaviour of the Oxyfuel and the post-combustion CO₂capture processes are evaluated and compared. The net efficiency of the conventional hard-coal-fired power plant decreases from 45.2% at full load to 41.6% at 40% load. The net efficiency with post-combustion CO₂capture using 7 m MEA as solvent decreases to 34.7% at full load and 30.2% at 40% load. The Oxyfuel process reaches in turn a net efficiency of 36.6% at full load and 32.3% at 40% load and shows therefore a benefit of 1.9%-points at full load compared to the postcombustion CO₂capture with MEA. The efficiency advantage of the Oxyfuel process compared to the post-combustion CO₂capture process remains constant at part load.Publicationtype: Conference PaperScopus© Citations 8 304 282