CFD Modeling of Multi-Fuel Suspension Co-Combustion and Calcination Processes Within a DDF Precalciner of Cement Kiln

2020 ◽  
Author(s):  
Eugen-Dan Cristea ◽  
Pierangelo Conti
Keyword(s):  
Alternative Fuels ◽  
Radiation Heat Transfer ◽  
Engineering Application ◽  
Raw Material ◽  
Cfd Modeling ◽  
Thermochemical Conversion ◽  
Cement Kiln ◽  
Discrete Phase Model ◽  
Local Flow ◽  
Dry Process

Abstract The paper reports a CFD engineering application for modeling the thermal-fluid dynamics and thermochemical conversion processes, which govern the conventional air-fossil fuel firing or multi-fuel co-processing, responsible for thermal sustain of raw material calcination process, within a dry process cement kiln. We simulate a Dual-Combustion and Denitration Furnace (DDF) precalciner, which co-combusts in suspension the petroleum coke (primary fuel) with alternative fuels (e.g., the pre-dried sewage sludge and/or the animal meat and bonemeal). CFD software package ANSYS Fluent R18.2 is used to build CFD reactive model and to perform the numerical simulations. The Eulerian–Lagrangian approach is usually employed for modeling turbulent multiphase reacting flows. Few turbulence and radiation heat transfer models are compared, to identify pros and cons of each model applicability and to determine which model is most suitable. The Discrete Phase Model (DPM), in Lagrangian framework, is employed for tracking petcoke/alternative fuels and limestone particle clouds. CFD analysis provides valuable insights into the DDF precalciner performance e.g., combustion and calcination characteristics, in-furnace NOx control strategy by combustion aerodynamics optimization (particularly the effect of Tertiary Air tangential inlet, which creates swirl and induces several local flow recirculation zones). The major predicted results e.g., exit degree of calcination, fuel burnout, gas species concentration fields etc., are quite well captured and validated against control system continuously logged operation data and the measurements collected by newly installed instrumentation.

CFD Simulation of Large Dust Collection Cyclones Positioned Vertically in Staggered Downward Cascade Arrangement

2013 ◽  
Author(s):  
Eugen-Dan Cristea ◽  
Pierangelo Conti
Keyword(s):  
Cfd Simulation ◽  
Solid Phase ◽  
Phase Particle ◽  
High Mass ◽  
Cfd Modeling ◽  
Cement Kiln ◽  
Dust Collection ◽  
Dry Process ◽  
Cascade Arrangement ◽  
Simulation Results

Three dimensional, time dependent Euler-Euler simulation approach for numerical calculation of multiphase strongly swirling turbulent gas-heavy laden particulate flow in large industrial collection cyclones, positioned vertically, in staggered downward cascade arrangement has been performed. The multiphase flow was featured high mass loading. This paper specifically addresses a CFD modeling of a “suspension preheater”, typical equipment for dry process cement kiln. Big sized cyclone separator is a key component of this device. The simulation case study was developed in the frame of the commercial general-purpose code ANSYS-Fluent R13. In cyclone separators the swirling gas motion induces a centrifugal force on the solid particulate phase which is the driving force behind the separation process. The turbulence disperses the solid particulates and enhances the probability that particles are discharged, as reject. Both phenomena are related to solid phase particle size distribution (PSD) and flow pattern into the collection cyclones. The multiphase turbulence was modeled using the RSM Mixture Turbulence Model. The simulation results were validated against industrial measurements carried out on an industrial suspension preheater, in the frame of heat and mass balance of cement kiln energy audit. The numerical simulation results were found in reasonable agreement with the collected industrial measurements. This CFD simulation represents a powerful engineering tool on behalf of the cement process engineer either for new cutting-edge design or for performance verification of an existing plant.

Hybrid Eulerian Multiphase-Dense Discrete Phase Model Approach for Numerical Simulation of Dense Particle-Laden Turbulent Flows Within Vertical Multi-Stage Cyclone Heat Exchanger

2018 ◽  
Author(s):  
Eugen-Dan Cristea ◽  
Pierangelo Conti
Keyword(s):  
Heat Exchanger ◽  
Carrier Phase ◽  
Phase Model ◽  
Cement Kiln ◽  
Dispersed Phase ◽  
Discrete Phase Model ◽  
Dry Process ◽  
Rotary Cement Kiln ◽  
Multi Stage ◽  
Discrete Phase

This article describes a CFD engineering application developed to investigate numerically the multiphase, non-isothermal, turbulent flow physics within the suspension preheater of a dry-process rotary cement kiln. The multi–stage cyclone preheater is a counter-current heat exchanger. We used the CFD flow solver ANSYS-Fluent R18.1. to accomplish this task. The hybrid Eulerian multiphase-dense discrete phase model is a coupled Eulerian-Lagrangian technique. The primary carrier-phase is treated as a continuum by solving the Navier-Stokes equations, while the secondary discrete dispersed-phase is solved by tracking the particle parcels through the calculated flow field. The multiphase turbulence of the carrier-phase is modeled using the Reynolds stress transport model. The dispersed-phase interactions are modeled through the specific collisions models provided by the kinetic theory of granular flow and/or discrete element method. The Eulerian multiphase-DDPM method provided a quiet stable solution for a medium/high mass loading (solid to gas mass ratio 0.89:1). The four-stage cyclone suspension preheater is analyzed for its operating performance i.e. overall pressure drop and global collection efficiency of cyclone stages, calcination degree at bottom cyclone stage, flue gas temperature at 1st. cyclone stage and availability to get more insight of very complex multi-phase flow patterns within this equipment. The set of industrial measurements, collected during a heat and mass balance of a dry process rotary cement kiln, were used to verify and to validate part of the simulation results.

Experimental Study on the Re-Bonded Magnesia - Zirconia Refractory for New Dry Process Cement Kiln

2011 ◽  
Vol 287-290 ◽  
pp. 823-826
Author(s):  
Hui Fang Zhang ◽  
Hong Liang Huang ◽  
Li Fang Zhang ◽  
Na Zheng ◽  
Fei Zhao
Keyword(s):  
Experimental Study ◽  
Particle Size ◽  
Sinter Temperature ◽  
Polyvinyl Alcohol ◽  
Hexavalent Chromium ◽  
Raw Material ◽  
Cement Kiln ◽  
Magnesite Powder ◽  
Dry Process ◽  
Zirconia Refractory

The use of magnesia-chrome refractories of the cement kiln can generate harmful hexavalent chromium in the environment and be hazardous to your health, so the study on the instead of magnesia-chrome refractories have become urgent issues. The raw material is made up of fused magnesite particles (particle size 0 to 3 mm), fine fused magnesite powder with the size less than 200 meshes and fine fused magnesia-zirconia’s powder with the size less than 320 meshes, polyvinyl alcohol and calcium lignosulfonate liquor being used as the combine. This paper discusses the effect of sinter temperature on sinter character of products.

Pilot Experiments on Co-Processing Oversized Products Screened from Aged Refuse in Cement Kiln

2012 ◽  
Vol 518-523 ◽  
pp. 3421-3426
Author(s):  
Chun Ping Li
Keyword(s):  
Alternative Fuels ◽  
Setting Time ◽  
Raw Material ◽  
Screw Conveyor ◽  
Cement Kiln ◽  
Main Process ◽  
Feeding Mode ◽  
Initial Setting Time ◽  
Intermittent Feeding ◽  
Aged Refuse

Re-processing of aged refuse with particle size of 100mm, heating value above 3000kcal/kg above, chlorine content of about 0.13% was added into cement kiln as alternative fuels using screw conveyor. The results show that: except for NOx, emission rate and concentrations of TSPs, HCl, HF, SO2, CO from cement kiln flue gas were increased and volatized significantly after adding alternative fuels. Dosage of 2t/h of alternative fuels affected little on kiln system, so, main process parameters were normal and no more substantial fluctuations, but, the amount of feeding coal at calciner were adjusted more frequently. Element of S in hot raw material into the kiln seemed no significant changes while K and Cl content was significantly increased within the manageable range. Compressive strength, flexural strength, water demand for normal consistency, surface area of clinker all reduced when using alternative fuels, initial setting time and final setting time were increased compared with clinker saturation. Adding alternative fuels saving of coal, but the actual effect of alternative fuel was less than theoretical results, indicating that intermittent feeding mode was not desirable.

Effects of Nickel on Properties of Cement Mortar Derived from the Co-Burning of Industrial Waste and its Leaching Behavior

2015 ◽  
Vol 1103 ◽  
pp. 121-127
Author(s):  
Suthatip Sinyoung ◽  
Ekkachai Taweekitwanit ◽  
Puangrat Kajitvichyanukul
Keyword(s):  
Hazardous Waste ◽  
Alternative Fuels ◽  
New Technology ◽  
Xrd Analysis ◽  
Raw Material ◽  
Cement Kiln ◽  
Leaching Behavior ◽  
Free Lime ◽  
Leach Test ◽  
Alternative Material

Burning of hazardous waste in cement kiln is the new technology based on waste derived and alternative fuels. Besides being the alternative way to destroy hazardous waste, this method provides alternative material as raw material or the fuel in the cement production process. This disposal method can be applied if the contaminant either does not appear in the emission or leach from cement to environment. This work focused on properties and the leaching behavior of nickel from cement. The resulting clinker was analyzed for the content of free lime and X-ray diffraction (XRD) analysis was done. The identification of MgNiO2 peaks in XRD pattern was found in all clinkers with nickel addition in the range of 0.5-2.0 wt.%. Results obtained from this part suggested that nickel incorporated in the clinker phase and may combine with magnesium to form the new compound as MgNiO2 during the burning process. To study the leaching behavior, M3051A, NEN:7341 and pH static leach test were used. Results showed that approximately 3% of nickel can be leached to environment. From the pH static leach test, nickel was effectively leached at pH 4 and the reachability of its decreased when the pH increased. In this work, Toxicity characteristic leaching procedure (TCLP) was also used to identify the cement as hazardous waste or non-hazardous waste. The results showed that raw material doped with nickel up to 2 wt.%, the cement was not classified as hazardous waste.

Numerical Investigation on Multiphase Reacting/Combusting Turbulent Flows: Aerodynamics, Kinetics, Heat and Mass Transfer Inside a Cement Kiln Precalciner

2019 ◽  
Author(s):  
Eugen-Dan Cristea ◽  
Pierangelo Conti
Keyword(s):  
Turbulent Flows ◽  
Stokes Equations ◽  
Fluid Dynamic ◽  
Radiation Heat Transfer ◽  
Engineering Application ◽  
Turbulence Models ◽  
Design Tool ◽  
Cement Kiln ◽  
Thermal Decomposition Mechanism ◽  
Limestone Calcination

Abstract This paper reports the modeling work to develop a computational fluid dynamics (CFD) engineering application, based on an appropriate 3D mathematical model able to perform the thermo-fluid dynamic numerical simulation of multiphase reacting/ combusting turbulent flows within a precalciner of an industrial four-stage cyclone preheater/precalciner cement kiln. In the precalciner furnace the hot micron-sized limestone (calcite/dolomite) meal, held in suspension, is quiet completely converted to quicklime (CaO(s)), and the CO2(g) by-product is driven-off during calcination process. Since, the thermal decomposition mechanism is a very endothermic reaction, the necessary heat is balanced by pulverized petcoke combustion. These major physical and chemical processes inside the precalciner are properly described by the 3-D Favre-averaged Navier-Stokes equations with the species transport equations, the energy equation and the state equation, to be solved by an Eulerian-Lagrange approach. The CFD solver employed in this study is the commercial CFD code ANSYS Fluent R18.2. The used built-in models/sub-models include turbulence models and near-wall treatment, model of traditional air-pulverized petcoke combustion, pulverized-limestone calcination model, as well as the sub-models for radiation heat transfer and turbulence-chemistry interaction. They are used to formulate the closures of the unclosed terms in the PDEs system. In summary, the trends of predicted results of limestone calcination and petcoke/TDF combustion processes in an industrial precalciner furnace are reasonable fair in confront to operation data measurable in the harsh environment conditions, typical for the pyroprocessing systems. The developed CFD engineering application can be used as an effective design tool for preliminary examination of the global effect of thermal-flow aerodynamics and turbulence on the precalciner processes.

scholarly journals TECHNICAL ANALYSIS OF PRODUCTS OF USED TIRES THERMOCHEMICAL CONVERSION

2019 ◽  
Vol 41 (4) ◽  
pp. 57-64
Author(s):  
E.V. Sklyarenko ◽  
L.Y. Vorobiov ◽  
D.A. Kirzhner ◽  
S.V. Plashykhin
Keyword(s):  
Alternative Fuels ◽  
Technical Analysis ◽  
Developed Countries ◽  
High Energy ◽  
Heat Of Combustion ◽  
Raw Material ◽  
Thermochemical Conversion ◽  
Solid Carbon ◽  
Pyrolysis Products ◽  
Exhaust Gas Cleaning

Introduction. Utilization of worn tires in the world is of great economic and ecological importance for all developed countries. This is due to the fact that worn tires are a source of long-term pollution of the environment by toxic components and a causative agent of the sanitary-epidemiological situation in their places of storage. Today, the most common method for disposing of tires is to burn them to produce energy that requires special technologies and combustion plants and exhaust gas cleaning systems. In addition, the disadvantage of this method is the increased CO2 emissions. One of the promising ways to dispose of tires is the technology of full carbon recycling by means of a preliminary thermochemical conversion, the result of which is the physico-chemical transformation of the organic part of the raw material into new gaseous, liquid and solid carbon-based energy products that can be used in the industry. In order to reduce the cost of transporting worn tires to large processing enterprises, promising is developing mobile thermochemical conversion units, which can carry out the processing of tires in places where they accumulate. The main way to control the quality of the products obtained is to determine their calorific value, by calorimetric and technical analysis. The purpose of the work is to determine the thermal characteristics of samples of pyrolysis of worn tires in a mobile conversion plant and to evaluate their potential use for energy purposes. Research results. The humidity, ash content and heat of combustion of raw materials in the form of crushed rubber of worn tires and products of its pyrolysis - liquid fuel and solid carbon have been investigated. High and net heat of combustion of analytical sample, fuel in dry state and in working condition of delivery is determined using the data of experimental measurements, taking into account corrections for the formation of sulfuric and nitric acid. The value of the net heat of combustion in the state of delivery for the crushed rubber of tires, liquid and solid pyrolysis products, respectively, amounted to 30.36; 40.79; 24.37 MJ / kg. Conclusion. The conducted studies showed high energy characteristics of the studied samples, which can be used as alternative fuels. The use of pyrolysis products does not require special installations. Their combustion can be carried out in existing installations without significant reconstruction.

scholarly journals Exergy analysis of conventional and hydrothermal liquefaction–esterification processes of microalgae for biodiesel production

2020 ◽  
Vol 18 (1) ◽  
pp. 874-881
Author(s):  
Laras Prasakti ◽  
Sangga Hadi Pratama ◽  
Ardian Fauzi ◽  
Yano Surya Pradana ◽  
Arief Budiman ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Exergy Analysis ◽  
Lipid Extraction ◽  
Hydrothermal Liquefaction ◽  
Raw Material ◽  
Biodiesel Production ◽  
Exergy Loss ◽  
Thermochemical Conversion ◽  
Third Generation ◽  
Land Utilization

AbstractAs fossil fuels were depleting at an alarming rate, the development of renewable energy has become necessary. One of the promising renewable energy to be used is biodiesel. The interest in using third-generation feedstock, which is microalgae, is rapidly growing. The use of third-generation biodiesel feedstock will be more beneficial as it does not compete with food crop use and land utilization. The advantageous characteristic which sets microalgae apart from other biomass sources is that microalgae have high biomass yield. Conventionally, microalgae biodiesel is produced by lipid extraction followed by transesterification. In this study, combination process between hydrothermal liquefaction (HTL) and esterification is explored. The HTL process is one of the biomass thermochemical conversion methods to produce liquid fuel. In this study, the HTL process will be coupled with esterification, which takes fatty acid from HTL as raw material for producing biodiesel. Both the processes will be studied by simulating with Aspen Plus and thermodynamic analysis in terms of energy and exergy. Based on the simulation process, it was reported that both processes demand similar energy consumption. However, exergy analysis shows that total exergy loss of conventional exergy loss is greater than the HTL-esterification process.

scholarly journals Effect of Biochar Prepared from Food Waste through Different Thermal Treatment Processes on Crop Growth

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 276
Author(s):  
Hang Jia ◽  
Haoxi Ben ◽  
Fengze Wu
Keyword(s):  
Crop Growth ◽  
Raw Material ◽  
Synthetic Methods ◽  
Thermochemical Conversion ◽  
Growth Trend ◽  
Wheat Growth ◽  
Preparation Methods ◽  
Treatment Processes ◽  
Ft Ir ◽  
The Impact

Biochar is generally accepted and increasingly valued in scientific circles as solid products in the thermochemical conversion of biomass, mainly because of its rich carbon content. The purpose of this research is to investigate the impact of biochar from different sources on wheat growth. In particular, this work focused on the effect of different preparation methods and raw material of biochar on the growth of wheat and aim to find a potential soil substitute that can be used for crop cultivation. Two synthetic methods were evaluated: hydrothermal conversion and pyrolysis. The characterization of biochar was determined to explore the impact of its microstructure on wheat growth. The results show that the yield of biochar produced from high-pressure reactor is significantly higher than that obtained by using microwave reactor. For example, the biochar yield obtained through the former is about six times that of the latter when using steamed bread cooked as biomass raw material. In addition, the growth trend of wheat indicates that biochar has different promoting effects on the growth of wheat in its weight and height. The pyrolyzed carbon is more suitable for wheat growth and is even more effective than soil, indicating that pyrolyzed biochar has more potential to be an alternative soil in the future. Moreover, this research tries to explore the reasons that affect crop growth by characterizing biochar (including scanning electron microscopy (SEM), biofilm electrostatic test (BET) and Fourier transform infrared (FT-IR)). The results indicate that the biochar containing more pits and less hydroxyl functional are more suitable for storing moisture, which is one of the significant factors in the growth of crops. This study provides evidence of the effects of biochar on crop growth, both in terms of microstructure and macroscopic growth trends, which provides significant benefits for biochar to grow crops or plants.

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