scholarly journals A Comprehensive, Three-Dimensional Analysis of a Large-Scale, Multi-Fuel, CFB Boiler Burning Coal and Syngas. Part 2. Numerical Simulations of Coal and Syngas Co-Combustion

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 856 ◽  
Author(s):  
Jaroslaw Krzywanski ◽  
Karol Sztekler ◽  
Mateusz Szubel ◽  
Tomasz Siwek ◽  
Wojciech Nowak ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Large Scale ◽  
Bituminous Coal ◽  
Circulating Fluidized Bed ◽  
Three Dimensional ◽  
Cfb Boiler ◽  
Start Up ◽  
Carbon Dioxide Concentrations ◽  
Secondary Air ◽  
Burning Coal

This paper presents the results of numerical computations for a large-scale OFz-425 CFB (circulating fluidized bed) boiler utilizing coal and syngas. Four different operating scenarios are considered, including the reference variant, corresponding to the conventional, mono-combustion of bituminous coal, and three tests involving replacement of secondary air and part of the coal stream with syngas fed by start-up burners. Pressure, gas velocity, temperature, and carbon dioxide distribution in the combustion chamber are discussed in the paper. The results indicate that the syngas supply leads to an increase in local temperature and carbon dioxide concentrations. The proposed concept is not advisable as it may lead to frequent emergency stops of the CFB boiler.

scholarly journals A Comprehensive Three-Dimensional Analysis of a Large-Scale Multi-Fuel CFB Boiler Burning Coal and Syngas. Part 1. The CFD Model of a Large-Scale Multi-Fuel CFB Combustion

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 964 ◽  
Author(s):  
Jaroslaw Krzywanski ◽  
Karol Sztekler ◽  
Mateusz Szubel ◽  
Tomasz Siwek ◽  
Wojciech Nowak ◽  
...  
Keyword(s):  
Large Scale ◽  
Circulating Fluidized Bed ◽  
Three Dimensional ◽  
Cfd Model ◽  
Cfb Boiler ◽  
Coal Sludge ◽  
Syngas Combustion ◽  
Computational Fluid Dynamics Cfd ◽  
Burning Coal ◽  
Complex Phenomena

The paper is focused on the idea of multi-fuel combustion in a large-scale circulating fluidized bed (CFB) boiler. The article discusses the concept of simultaneous coal and syngas combustion. A comprehensive three-dimensional computational fluid dynamics (CFD) model is developed, which allows us to describe complex phenomena that occur in the combustion chamber of the CFB boiler burning coal and syngas produced from coal sludge.

A 3D Model of Combustion in Large-Scale Circulating Fluidized Bed Boilers

2004 ◽  
Vol 2 (1) ◽  
Author(s):  
Karsten Luecke ◽  
Ernst-Ulrich Hartge ◽  
Joachim Werther
Keyword(s):  
Combustion Chamber ◽  
Fluidized Bed ◽  
Large Scale ◽  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Cross Sectional ◽  
Secondary Air

In a circulating fluidized bed (CFB) combustor the reacting solids are locally fed into the combustion chamber. These reactants have to be dispersed across the reactor's cross-sectional area. Since the rate of mixing is limited this leads to a mal-distribution of the reactants and to locally varying reaction conditions. In order to describe the influence of mixing a three-dimensional model of the combustion chamber is suggested. The model is divided into three sub-topics. First, the flow structure in terms of local gas and solids velocities and solids volume concentrations is described. Second, mixing of the solids and the gas phase is quantified by defining dispersion coefficients, and finally the combustion process itself, i.e. the reaction kinetics, is modelled. The model was validated against data from measurements in the large-scale combustor of Chalmers University of Technology in Göteborg/Sweden. Insufficient fuel mixing generated mal-distributions of locally released volatiles, which were the basis for the uneven reactants distribution at steady-state. In the case of two-stage operation, the injected secondary air did not reach immediately the reactor's center but was slowly mixed with the main gas flow. The concentration gradients hardly vanish before the exit of the combustion chamber.

Model-Based Analysis of Transient Behavior of Large Scale CFB Boilers

2003 ◽  
Author(s):  
Ari Kettunen ◽  
Timo Hyppa¨nen ◽  
Ari-Pekka Kirkinen ◽  
Esa Maikkola
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Air Flow ◽  
Model Parameters ◽  
Air Flow Rate ◽  
Process Data ◽  
Cfb Boiler ◽  
Flow Rates ◽  
Load Change ◽  
Secondary Air

The main objective of this study was to investigate the load change capability and effect of the individual control variables, such as fuel, primary air and secondary air flow rates, on the dynamics of large-scale CFB boilers. The dynamics of the CFB process were examined by dynamic process tests and by simulation studies. A multi-faceted set of transient process tests were performed at a commercial 235 MWe CFB unit. Fuel reactivity and interaction between gas flow rates, solid concentration profiles and heat transfer were studied by step changes of the following controllable variables: fuel feed rate, primary air flow rate, secondary air flow rate and primary to secondary air flow ratio. Load change performance was tested using two different types of tests: open and closed loop load changes. A tailored dynamic simulator for the CFB boiler was built and fine-tuned by determining the model parameters and by validating the models of each process component against measured process data of the transient test program. The know-how about the boiler dynamics obtained from the model analysis and the developed CFB simulator were utilized in designing the control systems of three new 262 MWe CFB units, which are now under construction. Further, the simulator was applied for the control system development and transient analysis of the supercritical OTU CFB boiler.

scholarly journals STEAM GASIFICATION OF SOME MONGOLIAN COALS

2017 ◽  
pp. 48-51
Author(s):  
Tungalagtamir B ◽  
Enkhtsetseg E ◽  
Chao Lumen ◽  
Narantsetseg M ◽  
Avid B ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Bituminous Coal ◽  
Steam Gasification ◽  
Coal Deposits ◽  
Gasification Rate ◽  
Product Gas ◽  
N2 Atmosphere ◽  
Carbon Dioxide Concentrations ◽  
Stainless Steel Reactor ◽  
Scale Reactor

The gasification tests for the Alagtolgoi and Ailbayan coal deposits were conducted in the temperature up to 850°C using bench scale reactor in order to evaluate product gas composition. Prior to the gasification experiments, the raw coal was pyrolysed in a stainless steel reactor under N2 atmosphere at a temperature of 500°C for 1 h. General behavior of the coal conversion was quite similar for both coals. The gasification tests show that an increase in temperature enhances the formation of hydrogen, carbon dioxide and carbon monoxide. The highest yield of hydrogen and carbon dioxide concentrations of the Ailbayan coal are achieved at temperature of 850°C, which were 2.859 mmol⋅g-1⋅min-1 and 1.054 mmol⋅g-1⋅min-1 respectively. However maximum rate of hydrogen for Alagtolgoi subbituminous coal reached around 800°C. Overall results show that the maximum gasification rate is reached earlier for subbituminous coal than for bituminous coal, but product gas evolution was higher for the investigated bituminous coal.

Status and Prospect of Large-Scale Circulating Fluidized Bed Boiler

2012 ◽  
Vol 516-517 ◽  
pp. 444-447
Author(s):  
Da Fu Ma ◽  
Xiao Hong Hao
Keyword(s):  
Fluidized Bed ◽  
Co2 Capture ◽  
Power Plants ◽  
Large Scale ◽  
Circulating Fluidized Bed ◽  
Present Situation ◽  
Supercritical Pressure ◽  
High Density ◽  
Cfb Boiler ◽  
Fluidized Bed Gasifier

The paper is focused on the present situation and the development of large-scale circulating fluidized bed (CFB) boilers. Several developed technology of CFB such as supercritical and ultra supercritical pressure CFB boilers for power plants, oxy-fuel CFB boiler for CO2 capture and high-density circulating fluidized bed gasifier for advanced IGCC/IGFC are introduced in this paper.

Optimize Selected of Anti-Attrition Ridge Parameters through Numerical Simulation in CFB Boiler Blended with Waste Sludge

2014 ◽  
Vol 525 ◽  
pp. 222-226 ◽  
Author(s):  
Bo Lou ◽  
Hai Liang Diao ◽  
Si Ke Wu
Keyword(s):  
Particle Trajectory ◽  
Circulating Fluidized Bed ◽  
Three Dimensional ◽  
Guangdong Province ◽  
Furnace Wall ◽  
Combustion Model ◽  
Cfb Boiler ◽  
Waste Sludge ◽  
Ring Core ◽  
Stochastic Particle

Combustion in boiler blended with waste sludge can cause serious abrasion in the furnace. In this paper, Fluent6.3 was applied to establish three-dimensional numerical combustion model based on k-ε turbulence equations and Lagrangian stochastic particle trajectory to analyze a CFB (Circulating Fluidized Bed) boiler of a power plant in Guangdong province. The results show that anti-attritions will break the ring-core adherent regurgitation of the particles thus reducing erosion of particles made to the furnace wall. Furthermore, a setting of three anti-attrition ridges can prolongate the life of the wall by 2.49 times. Increasing numbers and the length of ridges are beneficial to wall, which should be limited shorter than 150mm duo to heat tube slagging, and implementing a shape of trapezoid instead of rectangle all are derived as enhancements to the feature of anti-attrition of CFB.

scholarly journals A Mini-Review on Applications of 3D Printing for Microbial Electrochemical Technologies

2021 ◽  
Vol 9 ◽  
Author(s):  
Tae Hyun Chung ◽  
Bipro Ranjan Dhar
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Three Dimensional ◽  
Scaling Up ◽  
Time Lags ◽  
Platform Chemicals ◽  
Review Articles ◽  
Complex Design ◽  
Start Up ◽  
Bioenergy Generation

For the past two decades, many successful applications of microbial electrochemical technologies (METs), such as bioenergy generation, environmental monitoring, resource recovery, and platform chemicals production, have been demonstrated. Despite these tremendous potentials, the scaling-up and commercialization of METs are still quite challenging. Depending on target applications, common challenges may include expensive and tedious fabrication processes, prolonged start-up times, complex design requirements and their scalability for large-scale systems. Incorporating the three-dimensional printing (3DP) technologies have recently emerged as an effective and highly promising method for fabricating METs to demonstrate power generation and biosensing at the bench scale. Notably, low-cost and rapid fabrication of complex and miniaturized designs of METs was achieved, which is not feasible using the traditional methods. Utilizing 3DP showed tremendous potentials to aid the optimization of functional large-scale METs, which are essential for scaling-up purposes. Moreover, 3D-printed bioanode could provide rapid start-up in the current generation from METs without any time lags. Despite numerous review articles published on different scientific and applied aspects of METs, as per the authors’ knowledge, no published review articles explicitly highlighted the applicability and potential of 3DP for developing METs. Hence, this review targets to provide a current overview and status of 3DP applications for advancing METs and their future outlook.

Three-Dimensional Modeling and Model Validation of Circulating Fluidized Bed Combustion

2003 ◽  
Author(s):  
Kari Myo¨ha¨nen ◽  
Timo Hyppa¨nen ◽  
Jouni Miettinen ◽  
Riku Parkkonen
Keyword(s):  
Heat Flux ◽  
Fluidized Bed ◽  
Large Scale ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Three Dimensional ◽  
Hot Water ◽  
Combustion Model ◽  
Process Conditions ◽  
Model Parameters

This paper presents a three-dimensional, steady state combustion model for a circulating fluidized bed (CFB) furnace and several calculation cases which have been used for the validation of the model. The model includes essential submodels to describe the complex combustion process in a circulating fluidized bed boiler. These include the hydrodynamics of the bed, devolatilization of fuel, combustion of char, combustion of hydrocarbons, carbon monoxide and hydrogen, calcination and sulfation, fragmentation and attrition of solids, heat transfer, overall mass balance of the furnace, and three-dimensional balance equations based on the finite volume method. The code was initially developed in 1989, and it has been updated and improved over the years as new methods and new information have become available. The model is used for increasing process knowledge and for studying such phenomena inside the furnace which are often difficult or impossible to study by direct measurements. The knowledge obtained is then applied to optimize boiler design and process performance in terms of efficiency, economy and environmental issues. Reliable experiments and measurements in commercial boilers are used for the validation of the model and for tuning the model parameters. For the validation of a three-dimensional model, extensive profile measurements of the various parts of the furnace are required. This paper presents validation studies for an 80 MWth hot water boiler burning bituminous coal and for a 235 MWe subcritical boiler burning lignite. The measurements with these units included profile measurements of heat flux, pressure, temperature and gas composition under different process conditions. The model was tuned according to the measurements and used for the prediction of the heat flux profile of a large scale supercritical CFB boiler.

scholarly journals THE USE OF EXPERIENCE OF COAL COMBUSTION IN A CIRCULATING FLUIDIZED BED FOR DESIGNING OF MEDIUM CAPACITY STEAM BOILERS FOR BURNING OF WET WASTE OF COAL PREPARATION AND RDF IN UKRAINE

2020 ◽  
pp. 20-29
Author(s):  
A. Topal ◽  
I. Holenko ◽  
M. Yurchenko
Keyword(s):  
Fluidized Bed ◽  
Large Scale ◽  
Circulating Fluidized Bed ◽  
Lessons Learned ◽  
3D Design ◽  
Cfb Boiler ◽  
Eu Directive ◽  
Advanced Combustion ◽  
Steam Boilers ◽  
High Ash Coal

The necessity to implement advanced combustion technologies to utilize MSW/SRF/RDF and coal reject waste is an important problem for Ukraine to be solved. The introduction of such technologies will favor to involve annually about 2 mln t of RDF and partly cover deficit of bituminous coal, lack of which is currently faced. The technological niche for CFB combustion of RDF/SRF has certain optimal range bearing in mind technological, ecological (2010/75/EU Directive etc.) and financial performance. In view of this it seems reasonable to implement CFB for RDF/SRF firing starting from boiler steam capacity of 50-75 t/h while stoker firing of RDF could be efficiently implemented for lower range. The design of such boiler should rely upon lessons learned of commissioning and operating large-scale CFB boiler (having steam capacity of 670 t/h; 545/545 C) we obtained at Starobeshevo Power Plant in Ukraine. Accounting for the above the analysis of implementation and modifications made at large-scale CFB boiler (cyclones, seal pot, fluidized bed heat exchangers) has been done. The experience was used to design (along with KB “Energomashproekt”) medium-scale CFB boiler (having steam capacity of 75 t/h; 500 C) to burn high ash coal washering wastes and RDF/SRF. The sketch-3D-design of such boiler is presented with key performance. Bibl. 6, Fig. 4, Tab. 4.

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