Simulation of an Industrial Tangentially Fired Boiler Firing Metallurgical Gases

2014 ◽  
Vol 7 (1) ◽  
Author(s):  
Guangwu Tang ◽  
Bin Wu ◽  
Kurt Johnson ◽  
Albert Kirk ◽  
Chenn Q. Zhou
Keyword(s):  
Electrical Power ◽  
Combustion Process ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cfd Modeling ◽  
Combustion Model ◽  
Steel Mill ◽  
Operation Conditions ◽  
Boiler Operation ◽  
Industrial Boilers

In industrial environments, boiler units are widely used to supply heat and electrical power. At an integrated steel mill, industrial boilers combust a variable mixture of metallurgical gases combined with additional fuels to generate high-pressure superheated steam. Most tangentially fired boilers have experienced water wall tube failures in the combustion zone, which are thought to be caused by some deficiency in the combustion process. The challenge faced in this present process is that there are very limited means to observe the boiler operation. In this study, a three-dimensional computational fluid dynamics (CFD) modeling and simulation of an industrial tangentially fired boiler firing metallurgical gases was conducted. Eddy dissipation combustion model was applied on this multiple fuel combustion process. Simulation results obtained from the developed CFD model were validated by industrial experiments. A quick comparison of the flame shape from the simulation to the actual flame in the boiler showed a good agreement. The flow field and temperature distribution inside the tangentially fired boiler were analyzed under the operation conditions, and a wall water tube overheating problem was observed and directly related to the flow characteristics.

Simulation of an Industrial Tangentially Fired Boiler Firing Metallurgical Gases

2013 ◽  
Author(s):  
Guangwu Tang ◽  
Bin Wu ◽  
Kurt Johnson ◽  
Albert Kirk ◽  
Chenn Q. Zhou
Keyword(s):  
Electrical Power ◽  
Combustion Process ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cfd Modeling ◽  
Steel Mill ◽  
Operation Conditions ◽  
Boiler Operation ◽  
Computational Fluid Dynamics Cfd ◽  
Industrial Boilers

In industrial environments, boiler units are widely used to supply heat and electrical power. At an integrated steel mill, industrial boilers combust a variable mixture of metallurgical gases combined with additional fuels to generate high-pressure superheated steam. Most tangentially fired boilers have experienced water wall tube failures in the combustion zone, which are thought to be caused by some deficiency in the combustion process. The challenge faced in this present process is that there are very limited means to observe the boiler operation. In this study, a three-dimensional Computational Fluid Dynamics (CFD) modeling and simulation of an industrial tangentially fired boiler firing metallurgical gases was conducted. Simulation results obtained from the assembled CFD model were validated by industrial experiments. A quick comparison of the flame shape from the simulation to the actual flame in the boiler showed a good agreement. The flow field and temperature distribution inside the tangentially fired boiler were analyzed under the operation conditions, and a wall water tube overheating problem was observed and directly related to the flow characteristics.

scholarly journals Analytical and Numerical Feasibility Analysis of a Contra-Rotary Ramjet Engine

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 163
Author(s):  
Tomasz Laube ◽  
Janusz Piechna
Keyword(s):  
Numerical Simulations ◽  
Stokes Equations ◽  
Analytical Data ◽  
Combustion Process ◽  
Flow Characteristics ◽  
Combustion Model ◽  
Similar Data ◽  
High Rotational Speed ◽  
Jet Engine ◽  
Ramjet Engine

A new idea for a contra-rotary ramjet engine is presented. To define the theoretical limits of the non-typical, contra-rotary ramjet engine configuration, its analytical model was developed. The results obtained from that model and the analytical results were compared with those received from numerical simulations. The main weakness of existing rotary ramjet engine projects is the very high rotational speed of the rotor required for achieving supersonic inlet flow. In this paper, a new idea for a contra-rotary ramjet engine (CORRE) is presented and analyzed. This paper presents the results of analytical analysis and numerical simulations of a jet engine system with two rotors rotating in opposite directions. Contra-rotating rotors generate a supersonic air velocity at the inlet to the compressor at two times slower rotor’s speed. To determine the flow characteristics, combustion process, and engine efficiency of the double-rotor engine, a numerical solution of the average Navier-Stokes equations was used with the k-eps turbulence model and the non-premixed combustion model. The results of numerical simulations of flow and the combustion process inside the contra-rotary jet engine achieving a shockwave compression are shown and compared with similar data for a single-rotor engine design and analytical data. This paper presents only the calculation results of the flow processes and the combustion process, indicating the advantages of the proposed double-rotor design. The results of the numerical analysis were presented on the contours and diagrams of the pressure and flow velocity, temperature distribution, and mass fraction of the fuel.

Development and Validation of an Ignition Model for SI Engines

2006 ◽  
Author(s):  
Stefania Falfari ◽  
Gian Marco Bianchi
Keyword(s):  
Cfd Simulation ◽  
Combustion Process ◽  
Three Dimensional ◽  
Electrical Energy ◽  
Combustion Model ◽  
Test Case ◽  
Ignition Process ◽  
Mean Flow ◽  
Flame Kernel ◽  
Si Engines

In SI engines the ignition process strongly affects the combustion process. Its accurate modelling becomes a key issue for a design-oriented CFD simulation of the combustion process. Different approaches to simulate ignition have been proposed. The common base is decoupling the physics related to the very first ignition phase when a plasma is formed from that of the development of the flame kernel. The critical point of ignition models is related to the capability of representing the effect of ignition system characteristics, the criterion used for flame deposit and the initialisation of the combustion model. This paper aims to present and validates extensively an ignition model suited for CFD calculation of premixed combustion. The ignition model implemented in a customized version of the Kiva 3 code is coupled with ECFM Flamelet combustion model. The ignition model simulates the plasma/kernel expansion based on a lump evaluation of main ignition processes (i.e., breakdown, arc-phase and glow phase). A double switch criterion based on physical and numerical consideration is used to switch to the main combustion model. The Herweg and Maly experimental test case has been used to check the model capability. In particular, two different ignition systems having different amount of electrical energy released during spark discharge are considered. Comparisons with experimental results allowed testing the model with respect to its capability to reproduce the effects of mixture equivalence ratio, mean flow, turbulence and spark energy on flame kernel development as never done before in three-dimensional RANS CFD combustion modelling of premixed flames.

Carbon Monoxide Emission Improvements From Combustion System Upgrades at the Wheelabrator Portsmouth Refuse Derived Fuel Plant

2012 ◽  
Author(s):  
Samit J. Pethe ◽  
Michael L. Britt ◽  
Scott A. Morrison
Keyword(s):  
Carbon Monoxide ◽  
Electrical Power ◽  
High Elevation ◽  
Waste To Energy ◽  
Cfd Modeling ◽  
Combustion System ◽  
Steam Generation ◽  
Design Concepts ◽  
Refuse Derived Fuel ◽  
Boiler Operation

Wheelabrator Technologies Inc. (WTI) operates a waste-to-energy facility in Portsmouth, Virginia. At full capacity, a total of 2,000 tons/day of refuse derived fuel (RDF) can be fired in four identical boilers to generate a total of 600,000 lb/hr of steam and 60 MW of electricity. The boilers were originally designed to co-fire RDF and coal; however, coal burning capability was removed a few years after commissioning. The plant provides all of the process/heating steam and the majority of the electrical power to the nearby Norfolk Naval Shipyard. Historically, the boilers had not been able to reliably achieve carbon monoxide (CO) emissions compliance. CO emissions experienced during normal boiler operation would be more than twice the mandated emission limit. WTI’s goal was to improve the boilers’ CO emissions performance while achieving sustained boiler operation at higher steam generation and RDF firing rates. WTI contracted Jansen Combustion and Boiler Technologies, Inc. (JANSEN) to evaluate the operation of the boilers, to assess the overall feasibility of meeting WTI’s goals, and to develop design concepts to overcome boiler limitations. The project was initiated by an engineering site visit where boiler operating data was collected and evaluated to develop a baseline of boiler operation. Current and new combustion system arrangements were evaluated with Computational Fluid Dynamics (CFD) modeling. The results confirmed that the root cause of the poor CO emissions performance was the inadequate penetration and mixing of the original overfire air (OFA) system (comprised of multiple rows of small ports on the front and rear furnace walls). CFD modeling also showed increased CO emissions to result from non-uniform RDF delivery profiles generated by the original fuel distributors that were installed at a high elevation over the grate. Modeling of the furnace with larger and fewer OFA nozzles placed on the side walls in an interlaced pattern, and the installation of “new-style” RDF distributors at a lower elevation where the boiler’s original coal distributors formerly were located was shown to significantly improve CO burnout. From December 2010 to May 2011, the new combustion systems were installed on all four boilers. Subsequent testing has shown that CO levels have been lowered by more than 70% and boiler availability has been significantly improved. Nitrogen oxides (NOx) emissions, although slightly higher following the upgrade, are still within the NOx compliance limit. This paper describes the process that led to a successful project, including: data collection and analyses, CFD modeling, equipment design and supply, operator training, and start-up assistance.

CFD Modeling of the Performance of a Prechamber for Use in a Large Bore Natural Gas Engine

2005 ◽  
Author(s):  
Allan Kirkpatrick ◽  
Gi-Heon Kim ◽  
Daniel Olsen
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Combustion Process ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Main Chamber ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Cfd Models

The topic of this paper is the performance of a prechamber for use in a large bore two stroke natural gas engine. With increased regulation of emissions from stationary natural gas engines, there has been interest in modification of the combustion process, such as extending the lean limit, to reduce NOx emissions. One promising combustion technique uses an ignition prechamber. CFD models of a prechamber and the cylinder were developed in order to simulate the performance of a prechamber ignition system. The modeling included a full three dimensional transient analysis with scavenging, moving piston, and main chamber fuel injection. The CFD analysis included the fuel injection into the prechamber, pressurization by the inflowing main chamber gases, spark ignition, combustion, and flame propagation into the main combustion chamber. The computations indicated that the prechamber is more well mixed than the main engine chamber, with the prechamber mixture close to stoichiometric for better ignition. There is a strong, well-organized vortex in the prechamber induced by the incoming jet from the main chamber. The combustion flame in the prechamber travels in the direction of the gas vortex along lines of increasing equivalence ratio. The flame then propagates across the main cylinder in a very uniform fashion, indicating that there is sufficient energy to ignite the lean, partially mixed mixture in the main chamber. The orientation of the prechamber nozzle was also investigated, and an orientation of twenty degrees relative to the main chamber was found to produce a flame that did not impinge on the piston.

A Novel Undergraduate Combustion Teaching Approach Using Three-Dimensional Combustion Surfaces

2010 ◽  
Author(s):  
Michael David Costarell
Keyword(s):  
Carbon Dioxide ◽  
Power Generation ◽  
Flue Gas ◽  
Gas Turbines ◽  
Combustion Process ◽  
Three Dimensional ◽  
Teaching Approach ◽  
Transportation Fuels ◽  
Industrial Boilers ◽  
The Individual

Presently, mechanical engineering thermodynamic classes discuss the individual boiler, reciprocating engine, and gas turbine cycles, while other courses mention the combustion of individual natural gas, oil and coal fuels. Though these processes and fuels have different working fluids and air-to-fuel ratios they have predictable and comparable flue gas oxygen and carbon dioxide. Presented is a curriculum supplement that allows students to model three-dimensional plots of oxygen and carbon dioxide both as varied by hydrogen-to-carbon ratio and air-to-fuel ratio. The typical operating areas are then superimposed on these three-dimensional plots for industrial boilers (3 to 25 MW), power generation boilers (25 to 1,000 MW), reciprocating engines (0.1 to 5 MW), and gas turbines (0.1 to 100 MW). As power generation and transportation fuels become scarce and more expensive, future engineering employees must know how to minimize energy consumption and cost for a variety of fuels and combustion systems. This new teaching approach provides students a concise overall combustion curriculum that predicts the theoretical flue gas mole fraction of any common combustion process used with the major fuel sources.

CFD Modeling of Flame Structures in a Gas Turbine Combustion Reactor: Velocity, Temperature, and Species Distribution

2017 ◽  
Vol 15 (4) ◽  
Author(s):  
Alireza Bahramian ◽  
Mozhdeh Maleki ◽  
Bijan Medi
Keyword(s):  
Temperature Profile ◽  
Gas Turbine ◽  
Cfd Simulation ◽  
Flame Structure ◽  
Combustion Process ◽  
Three Dimensional ◽  
Species Distributions ◽  
Kinetic Mechanism ◽  
Cfd Modeling ◽  
Laser Measurements

Abstract This paper presents the computational fluid dynamics (CFD) simulation of a gas turbine combustor with methane-air fuel at atmospheric pressure. The velocity fields, temperature profile and species distributions have been numerically studied. The mathematical combustion models, namely Eddy Dissipation Concept (EDC) model coupled with detailed kinetic mechanism, and Finite Rate/Eddy Dissipation (FR-ED) model coupled with a simple global kinetic mechanism, have been used in numerical analysis considering a two-step oxy-combustion reaction kinetics model. Moreover, a series of CFD results with consideration of EDC model have been obtained by two- and three-dimensional simulations. An error analysis showed that the 3-D simulation with EDC model can accurately predict the velocity components, temperature profile, and species distributions of the combustion process and allow detailed investigation of the flame structure. The CFD results are in agreement with the experimental data obtained from laser measurements.

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 NUMERICAL SIMULATION OF UNSTABLE MODES FOR A SAFETY VALVE

2020 ◽  
pp. 141-157
Author(s):  
Raeder T. ◽  
◽  
Tenenev V.A. ◽  
Chernova A.A. ◽  
◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Safety Valve ◽  
Computing Time ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cfd Modeling ◽  
Dimensional Structure ◽  
Main Work ◽  
Gas Dynamic ◽  
Valve Operation

When designing pressure regulators, one needs to have a complete understanding of gasdynamic processes. The numerical algorithm for three-dimensional gas-dynamic modeling of a full cycle of spring safety valve operation is proposed, which allows one to significantly reduce the computing time. Grid reconfiguration during CFD modeling is provided by interpolation procedure using previously calculated grids. Calculations show that gas-dynamic numerical simulation should account for a three-dimensional structure of the unsteady flow and the motion of the disc. These factors are taken into account when calculating full cycle of the valve on a coarse grid with the use of correction functions for the force and flow characteristics of the valve. The correction functions are calculated by the false transient method in the three-dimensional formulation. Cyclograms of the valve operation demonstrate satisfactory agreement of the experimental and numerical simulation results. The agreement in the variation of gas-dynamic forces with time is observed, except for the transitional regime before the valve starts to close. In the main work area, the calculated values of the reduced force belong to a confidence interval.

Numerical Simulation and Optimization of a Carbon Monoxide Boiler

2016 ◽  
Author(s):  
Guangwu Tang ◽  
Bin Wu ◽  
Chenn Q. Zhou
Keyword(s):  
Heat Transfer ◽  
Carbon Monoxide ◽  
Flue Gas ◽  
Thermal Efficiency ◽  
Gas Flow ◽  
Combustion Process ◽  
Three Dimensional ◽  
Measurement Data ◽  
Flow Characteristics ◽  
Simulation And Optimization

Carbon monoxide (CO) boilers play an important role in the petroleum refining industry, completing the combustion of CO in the flue gas generated by the regeneration of fluidized cracking catalyst. The heat released by the CO combustion is used to generate steam for use in the refinery. The flue gas flow path can have a significant effect on the thermal efficiency and operation safety of the boiler. In this paper, a CO boiler which had been experiencing low thermal efficiency and high operation risks was studied. A three-dimensional (3D) computational fluid dynamics (CFD) model was developed with detailed description on the combustion process, flow characteristics and heat transfer. The results obtained from the model have good agreement with the plant measurement data. The heat transfer between the tubes and the combustion flue gas was optimized by adding a checker wall.

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