1,721,089 research outputs found
Improvement of SO2 removal with application of wall rings and advanced CFD modeling. The case of FGD unit Megalopolis
No full textMegalopolis SES is a lignite-fired steam-electric power plant (850 MW) located in southern Greece. The plant consists of four units. Unit III is retrofitted with a WFGD unit in order to meet the emission values of LCP 2001/80/EC. The WFGD flue gas treatment system removes SO2 by scrubbing the flue gas with a limestone / gypsum process. Flue gas is treated in the absorber by passing the flue gas stream through proper spray levels. The gas flows upward through the absorber countercurrent to the spray liquor flowing downward through the absorber. Slurry is pumped through banks of spray nozzles to atomize it to fine droplets and uniformly contact the gas. The droplets absorb SO2 from the gas, facilitating the reaction of the SO2 with reagent in the slurry. The quantity of liquid sprayed relative to flue gas is related to the SO2 collection efficiency needed and is referred to as liquid-to-gas (L/G) ratio. Higher L/G ratios improve SO2 removal by exposing the gas to more absorbing liquor. However, higher L/G ratios also consume more power. A CFD modelling of the absorber has been used to define gas and liquid distribution inside of the absorber with the purpose to combine the optimised SO2 removal with the lowest possible power consumption. The paper shows the results of the CFD study on Megalopolis III WFGD containing the fluid dynamic optimisation of the nozzles arrangement including the wall ring (patented by Alstom) location
Modeling of the fluid dynamics and SO2 absorption in a gas–liquid reactor
No full textThis paper illustrates a computational fluid dynamic (CFD) model of a counter-current Open Spray Tower desulphurisation reactor and its application in the simulation of a full-scale industrial equipment. The raw flue gas flows upward while a suspension of water and limestone is sprayed downward from different heights. Thereby sulfur dioxide is washed out of the gas.
The two-phase gas–liquid flow inside the equipment has been simulated with an Euler–Lagrange approach using a commercial CFD code, while a model for the SO2 absorption has been developed and implemented in the software through dedicated modules. Physical absorption is modeled using dual-film theory and appropriate empirical and semi-empirical correlations. The aqueous phase chemistry accounts for the instantaneous equilibrium reactions of eight dissolved species into a slurry droplet. The model is used to simulate an industrial plant at different operating conditions. The numerical results are in good agreement with the measured values of pressure drop and sulphur removal efficiency
A return to Thirteen Hongs : thinking of the future while looking at the past
No full textThe ILAUD Seminar “ Where does the new city come from?” was held from March 5 to 7 at the Yellow House in Guangzhou, in the main campus of the South China University of Technology, with the participation of researchers and scholars from Argentina, South Africa, Hong Kong, India, Japan, USA, Brasil, PR China,Italy
The seminar had two objectives:
1. To discuss issues connected with the elements that gave rise to and cha- racterised an urban system or a portion of a city, but at the same time were blurred by following developments and changes. How important are they in order to understand some aspects of contemporary cities? Can they be useful in shaping their future developments? Is it worthwhile to trace and eventually emphasize them? The matter is relevant in a moment when ci- ties are striving to enhance their identity and there is an increasing effort to capitalize on their history. And it is also important to explore more in depth the relationship between tradition and innovation in urban planning and architectural design.
This book collects a set of papers on different aspects of these problems that were presented and discussed during the Seminar.
2. To select the study area for the 2010 ILAUD Laboratory that would have taken place from November 29 to December 12 in Guangzhou. The Labo- ratory should have focused on the “13 Hongs area” in the Liwan District. In this area were once located several factories-warehouses (the Hongs). They were operated by Chinese, British, Danish, Dutch, Spanish, Swedish and US entrepreneurs. For a long while the area has been the main point of eco- nomic and technological exchange between the Western World and China. The Hongs are no more there but the neighbourhood still has a very vibrant commercial life and is one of the entertainment attractions of Guangzhou
Direct numerical simulation and RANS comparison of turbulent convective heat transfer in a staggered ribbed channel with high blockage
Get PDFA turbulent convective flow of an incompressible fluid inside a staggered ribbed channel with high blockage at ReH≈4200 is simulated with direct numerical simulation (DNS) and Reynolds-averaged NavierStokes (RANS) techniques. The DNS results provide the reference solution for comparison of the RANS turbulence models. The kε realizable, kω SST, and v2f model are accurately analyzed for their strengths and weaknesses in predicting the flow and temperature field for this geometry. These three models have been extensively used in literature to simulate this configuration and boundary conditions but with discordant conclusions upon their performance. The v2f model performs much better than the kε realizable while the kω SST model results to be inadequate
CFD modeling of the Dry-Sorbent-Injection process for flue gas desulfurization using hydrated lime
No full textMultiphase Euler–Lagrange CFD simulation applied to Wet Flue Gas Desulphurisation technology
No full textThe gas and liquid hydrodynamics inside an Open Spray Tower has been simulated using a commercial CFD code, while a model that treats the absorption process of SO2 has been developed and implemented in the software through dedicated modules. Besides SO2 absorption also evaporation of slurry droplets and droplet-wall interaction are considered, the latter modeled with an empirical correlation and implemented in a sub-module.
The continuous gas phase has been modeled in an Eulerian framework, while the dispersed liquid phase with a Lagrangian approach by tracking a large number of particles through the computational domain. Physical absorption of SO2 has been modeled using dual-film theory and appropriate empirical and semi-empirical correlations. The model for aqueous phase chemistry considers instantaneous equilibrium reactions of eight dissolved species into a slurry droplet, namely: SO2aq, CO2aq, H+, OH-, HSO3-, SO3--, HCO3-, CO3--. The empirical droplet-wall interaction model handles impact, deposition and splashing events occurring when a liquid particle hits an internal element of the scrubber. A pilot plant OST has been simulated and the numerical results show good agreement with the experimental values of pressure drop, temperature and sulphur dioxide removal efficiency
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
CASTOR study on technological requirements for flue gas clean-up prior to CO2-capture
No full textThe objective of this study has been to investigate the feasibility and costs of reducing the concentrations of constituents such as SO2 and NO2 in coal derived flue gases down to or approaching the levels required by the amine scrubber suppliers. This has been carried out for three separate boilers 600MW, 1000MW and 380MW firing respectively low sulphur bituminous coal, a pre-dried German lignite and a conventional high moisture lignite from Greece
THERMO-CHEMICAL EULER-LAGRANGE CFD ANALYSIS APPLIED TO WET FLUE GAS DESULPHURISATION TECHNOLOGY
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