Simulation of a Scaled down 250 MWe CFB Boiler Using Computational Particle Fluid Dynamics Numerical Model

2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Vidya Venkatesan ◽  
Lakshminarasimhan Mukundarajan ◽  
Anantharaman Narayanan
Keyword(s):  
Fluid Dynamics ◽  
Particle Size ◽  
Circulating Fluidized Bed ◽  
Solid Phase ◽  
Lagrangian Model ◽  
Inventory Level ◽  
Solids Concentration ◽  
Commercial Code ◽  
Actual Operation ◽  
Computational Resources

Abstract Eulerian-Eulerian approach and conventional Eulerian-Lagrangian model are computationally exhaustive for modelling circulating fluidized bed (CFB) riser which has wide particle size distribution and billions of particles Alternatively, the relatively recent Eulerian- Lagrangian computational particle fluid dynamics (CPFD) model enables simulation of the CFB system with lesser computational resources. Most of the published studies on CPFD simulations of CFB risers deal with single grate system. The present study aimed to investigate the performance of the CPFD model for predicting solids distribution in a CFB riser with pant-leg structure (dual grate) and characteristics similar to a commercial boiler. Experiments conducted in a scaled down 250 MWe CFB facility according to Glicksman’s simplified similarity laws for fluidized beds were simulated using commercial code Barracuda. The bottom dense bed, upper lean solid phase, increase in bottom bed voidage with increasing fluidizing velocity and reducing solids inventory, decrease in bottom bed solids concentration with decrease in particle size and exchange of solids between the legs typically occurring in a CFB with pant-leg structure were successfully captured by the CPFD calculations. Simulation results showed that the upper solids concentration is hardly influenced by the solids inventory level in line with the experimental observation, therefore the amount of solids inventory can be optimized during actual operation. The predicted pressures varied from the average experimental pressure data within the range –10 to 39 %.

Performance evaluation of a supercritical circulating fluidized bed boiler for power generation under flexible operation

2021 ◽  
pp. 095765092199396
Author(s):  
Matteo Bruzzone ◽  
Silvia Ravelli
Keyword(s):  
Power Generation ◽  
Fluidized Bed ◽  
High Performance ◽  
Circulating Fluidized Bed ◽  
Thermal Power ◽  
Rankine Cycle ◽  
Hard Coal ◽  
Cfb Boiler ◽  
Power Cycles ◽  
Commercial Code

It is well known that the Łagisza power plant in Poland is the world’s first supercritical circulating fluidized bed (CFB) boiler, whose commercial operation started on June 2009. It has attracted a great deal of interest and operational data are publicly available, therefore it has been chosen as the object of the present study aimed at assessing load and fuel flexibility of supercritical CFB plants. First, the thermal cycle was modelled, by means of the commercial code Thermoflex®, at nominal and part load conditions for validation purposes. After having verified the validity of the applied modelling and simulation tool, the advantage of having supercritical steam combined with CFB boiler over subcritical steam and pulverized coal (PC) boiler, respectively, was quantified in terms of electric efficiency. As a next step, the designed fuel, i.e. locally mined hard coal, was replaced with biomass: 100% biomass firing was taken into account in the case of subcritical CFB boiler whereas the maximum share of biomass with coal was set at 50% with supercritical CFB boiler, consistently with the guidelines provided by the world leading manufacturers of CFB units. A broad range of biomass types was tested to conceive mixtures of fuel capable of preserving quite high performance, despite the energy consumption in pretreatment. However, the overall efficiency penalty, due to biomass co-firing, was found to potentially undermine the benefit of supercritical steam conditions compared to conventional subcritical power cycles. Indeed, the use of low-quality biomass in thermal power generation based on steam Rankine cycle may frustrate efforts to push the steam cycle boundaries.

scholarly journals Variation of the Chemical Composition of Waste Cooking Oils upon Bentonite Filtration

Resources ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 108 ◽  
Author(s):  
Alberto Mannu ◽  
Gina Vlahopoulou ◽  
Paolo Urgeghe ◽  
Monica Ferro ◽  
Alessandra Del Caro ◽  
...  
Keyword(s):  
Particle Size ◽  
Chemical Composition ◽  
Solid Phase ◽  
Volatile Fraction ◽  
X Ray Diffraction ◽  
Specific Chemical ◽  
Waste Cooking Oils ◽  
Main Components ◽  
Cooking Oils ◽  
Chemical Groups

The chemical composition and the color of samples of waste cooking oils (WCOs) were determined prior to and after filtration on two different pads of bentonite differing in particle size. The volatile fraction was monitored by headspace solid-phase microextraction (HS-SPME) coupled with gas-chromatography, while the variation of the composition of the main components was analyzed by 1H NMR. Both techniques allowed the detection of some decomposition products, such as polymers, terpenes, and derivatives of the Maillard process. The analysis of the chemical composition prior to and after bentonite treatment revealed a tendency for the clays to retain specific chemical groups (such as carboxylic acids or double bonds), independent of their particle size. A pair comparison test was conducted in order to detect the sensory differences of the intensity of aroma between the WCO treated with the two different bentonites. In addition, characterization of the bentonite by means of powder X-ray diffraction (XRD) and thermogravimetric measurements (TG) was performed.

scholarly journals Comparison of solid phase closure models in Eulerian-Eulerian simulations of a circulating fluidized bed riser

2019 ◽  
Vol 195 ◽  
pp. 39-50 ◽  
Author(s):  
Markku Nikku ◽  
Alexander Daikeler ◽  
Alexander Stroh ◽  
Kari Myöhänen
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Solid Phase ◽  
Closure Models

Transportation Performance of Highly Concentrated Coal-Water Slurries Prepared from Indian Coals

2014 ◽  
Vol 592-594 ◽  
pp. 869-873 ◽  
Author(s):  
Arunanshu Chakravarthy ◽  
Satish Kumar ◽  
S.K. Mohapatra
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Rheological Behaviour ◽  
Pseudoplastic Fluid ◽  
Ansys Fluent ◽  
Water Slurry ◽  
Solids Concentration ◽  
Coal Water Slurry ◽  
Indian Coals ◽  
Fluid Behaviour

The rheological behaviour of concentrated coal-water slurries prepared from three different Indian coals were investigated using an Anton Paar rheometer. The perspective was laid in to study the effect of solids concentration on the rheological behaviour of coal water slurry. It was observed that coal water slurry exhibited non-Newtonian pseudoplastic fluid behaviour at concentrations above 30 % by weight. The apparent viscosity varied with the amount of coal in the slurry. The rheological data were utilized to predict the pressure drop characteristics of coal water slurry flowing through a 53 mm diameter slurry pipeline using ANSYS Fluent 14.0 computational fluid dynamics code.

scholarly journals Determination of Phase-Eigenvalues by Rational Factorization and Enhanced Simulation of Two-Phase Mass Flow

2019 ◽  
Vol 2 (2) ◽  
pp. 61-77
Author(s):  
Puskar R. Pokhrel ◽  
Bhadra Man Tuladhar
Keyword(s):  
Fluid Dynamics ◽  
Debris Flows ◽  
Lateral Pressure ◽  
Solid Phase ◽  
Fluid Phase ◽  
Factorization Method ◽  
Phase Interaction ◽  
Two Phase ◽  
Simulation Results

In this paper, we present simple and exact eigenvalues for both the solid- and fluid-phases of the real two-phase general model developed by Pudasaini (2012); we call these phase-eigenvalues, the solid- phase-eigenvalues and the fluid-phase-eigenvalues. Results are compared by applying the derived phase- eigenvalues that incorporate the phase-interactions in the two-phase debris movements against the simple and classical solid and fluid eigenvalues without any phase interaction. We have constructed several different set of eigenvalues including the coupled phase eigenvalues by using rational factorization method. At first, we consider for general debris height; factorizing the solid and fluid lateral pressure contributions by considering the negligible pressure gradient; negligible solid lateral pressure; negligible fluid lateral pressure; negligible solid and fluid lateral pressure. Secondly, for a thin debris ow height, we also construct the fourth set of eigenvalues in three different cases. These phase-eigenvalues incorporate strong interaction between the solid and fluid dynamics. The simulation results are produced by taking all these different sets of coupled phase-eigenvalues and are compared with the classical uncoupled set of solid and fluid eigenvalues. The results indicate the importance of phase-eigenvalues and supports for a complete description of the phase- eigenvalues for the enhanced description of real two-phase debris flows and landslide motions.

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