In 2007 RWE Power, BASF and Linde entered into a cooperation to develop an optimized post combustion capture technology for power plants. In mid-2009 a CO2 capture pilot plant will be commissioned at RWE Power's lignite-fired power plant at Niederaussem, Germany. The pilot plant comprises all significant components of a large post combustion capture plant but on a smaller scale. Some capture process optimization measures are implemented that should increase the overall efficiency and reduce the costs of a commercial capture plant. The design of the pilot plant - engineering, procurement and construction by Linde - allows testing the performance and stability of optimized CO2 solvents, which BASF is currently developing. On the basis of an elaborated solvent selection methodology (pre-selection, screening, etc.) comprehensive experiments are carried out in order to examine solvent performance, and some measures for the optimization of the process configuration are developed. The 18-month pilot plant testing programme will allow the performance of the optimized solvent and the process to be evaluated.
Within the transatlantic project LAUNCH, solvent management strategies are validated by test campaigns at four capture plants with an adequate plant size and in an industrial environment (3 pilot facilities with a capture capacity of up to 0.4 tCO2/h and a commercial plant with 12 tCO2/h). At the capture pilot plant at Niederaussem, which separates in 24/7 mode the CO2 from the flue gas of the adjacent 1,000 MW lignite-fired block of the power plant, three degradation control technologies with different effect mechanisms are investigated in testing campaigns with the so-called CESAR1 solvent (>14,000 testing hours with an aqueous solution of 3.0 molar (~26.74 wt.-%) 2-amino-2-methylpropan-1-ol (AMP) and 1.5 molar (~12.92 wt.-%) piperazine (PZ): adsorptive removal of trace elements from the solvent by active carbon, removal of ionic trace elements from the solvent by ion exchange and removal of NO2 from the flue gas by thiosulfate/sulfite dosing. Activation of carbon and particle filters after 5,184 and 6,048 hours testing time resulted in a removal of coloring agents, iron and nickel from the solvent. Additionally, the increase of Cl-, SO42- and NO3- concentrations could be reduced, but no clear effect on the solvent degradation rate was observed. Anionic degradation products and trace components can be effectively removed from the aged solvent by ion exchange with an anionic exchange resin. Laboratory tests with the anionic resin and three cationic resins provide promising results to remove metal ions from the solvent. As iron can be removed from the solvent using the anionic resin, but not nickel, this is a strong indication that iron is dissolved in the solvent in the form of an anionic complex, which highlights the importance of the solvent matrix when investigating the catalytic effect of metal ions on amine degradation. Despite a concentration of 175 mmol/kg thiosulfate and 32 mmol/kg sulfite and a pH value of >8.5 of a scrubbing solution in a pre-treatment scrubber, it was not possible to remove NO2 from the flue gas. Laboratory tests confirmed the effect of the pre-treatment concept. Either the mass transfer is not sufficient in the scrubber or new NO2 is formed after the pre-treatment from NO in the flue gas. This will be
In the ALIGN-CCUS project a full CCU-chain will be demonstrated as an element for large-scale energy storage together with CO2 conversion and CCU-fuel usage as a promising blue print for sector coupling. The demonstration comprises: amine-based CO2 post-combustion capture, liquefaction and storage processes at the lignite fired power plant at Niederaussem (liquefied CO2 pressure 16.5 bar(a) - 17.5 bar(a), temperature -26.5 °C), an alkaline water-electrolysis unit (140 kWel, specific power consumption 4.5 kWh/mN³ H2 at 1.0 A/cm²), to split water into hydrogen and oxygen and an one-step methanol/dimethyl ether (DME) synthesis unit (approx. 50 kg DME/day from 180 kg CO2/day). A diesel engine of a stationary power generator (240 kWel) will be adapted to the use of DME to demonstrate peak and back-up power production in the energy sector. Additionally a passenger car will be modified for the utilization of oxymethylen dimethyl ether (OMEn), a diesel substitute for the transport sector that could be produced out of the CCU base chemicals methanol and DME. Based on real data from the demonstration plant the integration costs and environmental benefits of the CCU-chain technology are evaluated and optimised by a techno-economic-ecological assessment. A promising optimization measure for the synthesis process is the in-situ removal of water in the reversed water-gas shift reaction to increase efficiency and yield. For the application of DME as a fuel for peak- and back-up power production an optimised concept for the integration of the power generator into the existing power plant infrastructure will be developed.
Solvent degradation does not solely mean loss of solvent and increasing CO2 capture cost, but has also an effect on emissions, corrosion and foaming. Even for the well-known 30wt% monoethanolamine (MEA) solvent system, published specific solvent losses from capture facilities differ by one order of magnitude (~0.3 to 3.6 kg/t CO2). Based on the results from an ongoing 12,000 hours testing campaign with 30wt% aqueous MEA at the post combustion capture pilot plant at the lignite-fired power plant at Niederaussem, it is validated, how the time-dependent contents of degradation products and trace components that might act as catalysts for degradation are developing during long-term operation and which countermeasures against degradation could be applied. A solvent degradation network model has been established to estimate the rate of solvent degradation as a function of the flue gas composition, capture plant design and operating conditions and to compare the results from Niederaussem with the data received from the other pilot plants and testing facilities which are part of the ALIGN-CCUS project (Technology Centre Mongstad (NOR), pilot rig at Tiller, Trondheim (NOR), PACT facilities at Sheffield (UK)). For the analysis of the degradation process two advanced online-solvent monitoring tools will be used. Regarding the determination of the solvent loss due to emissions, dedicated test campaigns on the dynamic behavior of the capture plant have been carried out aiming at emission control strategies for certain flexible operational scenarios. For a better understanding of the aerosol formation mechanism and the behavior of aerosol nuclei within the absorber column measurements of the particle size distribution, the particle number concentration and the aerosol composition have been performed.
For the first time a full CCU chain for the production of the e-fuel dimethyl ether (DME) from captured CO2 and electrolytically produced H2 was demonstrated in the European project ALIGN-CCUS. In addition to the development, construction and operation of the Power-to-DME plant, the demonstration comprised also the successful use of DME as a fuel for peak and back-up power generation (Power-to-DME-to-Power) and of OME (polyoxymethylene dimethyl ethers, which can be produced from DME) as a fuel for passenger cars. Detailed and comprehensive comparative techno-economic analyses of Power-to-Fuel processes and Life Cycle Assessment following a "cradle-to-grave" approach provided the basis for the evaluation of the technology chain. Both objectives - to present the potential of CCU regarding climate protection and to demonstrate its benefit and socio-economic value as an element for large-scale energy storage and sector coupling - have been achieved.
As part of the development cooperation of RWE Power, BASF and Linde - aiming at an advanced optimised CO2-scrubbing technology for power plant application - the first post-combustion capture pilot plant in Germany was constructed and commissioned at the lignite-fired 1,000 MW Niederaussem power station in 2009. The pre-assembly of the pilot plant started in October 2008 and commissioning took place in July 2009 as planned. 7.2 t of CO2 per day can be captured from a flue gas slipstream of the power plant downstream of the desulphurisation plant (FGD). The pilot plant comprises optimised components such as a flue gas pre-scrubbing direct contact cooler unit as well as a lean liquid cooler and an interstage cooler that both allow returning the solvent at different absorber heights. During a 6-month campaign, all aspects of the optimised process configuration were tested using 30%-weight MEA as benchmark solvent and the performance of a new advanced amine-based solvent developed by BASF was trialled. This paper summarises the operational experience gained and compares some of the results obtained for MEA with those of the new amine-based solvent.
After a 13,000-hour test campaign with aqueous 30 wt% MEA (2-aminoethanol) solvent at the CO2 capture pilot plant at Niederaussem, another long-term test was carried out as part of the ALING-CCUS project. This test ran for more than 12,275 hours with aqueous AMP/PZ (2-Amino-2-methyl-1-propanol/piperazine) solvent, named CESAR1 (3.0 molar AMP (~ 26.74 wt%) and 1.5 molar PZ (~ 12.92 wt. %)). A minimum specific reboiler duty of 2,970 MJ/tCO2 was identified for the capture plant operation with four active absorber beds (total 16 m packing height). Neither a lower desorber pressure of 1.5 bar(a), instead of 1.75 bar(a), nor a change of the different positions of intercooling had a significant effect on energy consumption. Reduction of the active packing height to three beds (i.e., 12 m), resulted in a moderately higher specific energy demand (+100 MJ/tCO2). Tests with CO2 capture rates between 90 and 98% showed only a small increase of the specific energy demand at 95% (+20 MJ/tCO2) and four active packings (98%: + 250 MJ/tCO2). The average solvent consumption of CESAR1 during 400 days of operation was 0.45 kg/tCO2 and is lower than for MEA if the phase of accelerated non-linear degradation of MEA is taken into account. CESAR1 follows a slow-progressing linear degradation behavior; neither a critical metal ion concentration threshold value could be found that triggers fast degradation nor a correlation between accumulated trace components or metal ion concentrations in the solvent and the degradation rate was observed. Highly transient tests were conducted to investigate the dynamic behavior of the capture plant and subsequently special settings were chosen to stimulate high emissions for the investigation of aerosol-based emissions, connected with performance tests of several emission mitigation measures: single water wash, double water wash, acid wash, dry bed, wet electric precipitator and flue gas pre-treatment. When applying the dry bed configuration, emissions of AMP between 15 - 20 mg/Nm3, PZ between 3 - 7 mg/Nm3, and NH3 below 3 mg/Nm3 were achieved.
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