G. Scheffknecht

Analysis and Comparison of Reactivity and CO2 Capture Capacity of Fresh Calcium-Based Sorbents and Samples From a Lab-Scale Dual Fluidized Bed Calcium Looping Facility

Naturally occurring limestone and samples from a lab-scale dual fluidized bed (DFB)calcium looping test facility were analyzed in a thermogravimetric analyzer. The reactivityof the samples evaluated at typical carbonation conditions prevailed in the carbonatorwas compared with raw samples. The rate of carbonation and carbonation capacity ofthe samples were compared with respect to the following three categories: number ofcalcination-carbonation cycles, carbonation temperature, and CO2 concentration. It issuspected that the much lower activity of the DFB sample is attributed to the differencesin experimental conditions, i.e., partial carbonation of the DFB particles, fast heatingrate in the calciner and thus a rapid calcination reaction, and particle attrition in thecirculating fluidized bed calciner riser. These harsh conditions lead to sintering and thusa loss of surface area and reactivity. Sintered DFB samples showed low (nearly one-thirdof the raw samples) but stable conversions with increasing number of cycles. Hydrationwas used as an attempt to regenerate the lost capture capacity of partially carbonatedand sintered DFB sample. Hydration of the DFB sample was successful in increasing themaximum capture capacity in the fast reaction regime to values almost as high as that ofa fresh sample in its first carbonation cycle. Although more investigation is required toinvestigate the effect of hydration on the CaO particle morphology, a process modificationto enhance the CO2 capture efficiency of the carbonator via particle hydration wasproposed.

Flue-gas Coupling Of A Waste Incinerator With ALignite-fired Coal Boiler: Assessment Of TheBest-suited Injection Concept By Computational

The work presented in this paper focuses on the combustion behaviour of the coupled UPSWING (Unification of power plant and solid waste incineration on the grate.) process as well as on the reduction and destruction of pollutants like NOx and PCDD/F. The concept, which has been developed by the Forschungszentrum Karlsruhe, describes the coupling of a waste incinerator to a coal-fired power plant for heat and/or electricity generation, both on the steam and on the flue gas side. Possible injection concepts for the incinerator flue gases were investigated by large-scale CFD simulation in order to evaluate the impact of a wet, NOx-rich flue gas stream on the overall combustion behaviour of a pulverised coal-fired boiler. The necessary input data for the large-scale simulation was elaborated in various experiments at a semi-technical combustion reactor. The acquired data was used to validate the reliability of the coal combustion model as a prerequisite for the large-scale simulation. The results of both experimental and theoretical work are used to determine the best-suited coupling concept.