Engineering Commons^™

Improving The Conversion In Fluidised Beds With Secondary Injection, Dana Christensen, John Nijenhuis, J. Ruud Van Ommen, Marc-Oliver Coppens

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The effect of secondary injection on the performance of a fluidised bed reactor has been studied. A modified Kunii and Levenspiel model was used to predict the effect on conversion and indicates that the reduction in bubble size caused by secondary injection results in a significant increase. This effect was confirmed experimentally, although the model appears to underestimate the experimental values.

Gas-Solid Structure In The Vicinity Of A Sparger Nozzle In A Fluidized Bed, Pierre Sauriol, Heping Cui, Jamal Chaouki

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

An experimental approach is proposed to investigate the gas-solid structure in the vicinity of a sparger nozzle in a fluidized bed. The local hydrodynamics were studied under injection velocities ranging between 0 and 100 m/s and three orientations. A fiber-optic probe was used to measure the instantaneous local particle holdup near the tip of the sparger nozzle. Under the investigated conditions, the local gas-solid structure was influenced on the measurement position, nozzle orientation and injection velocity. Four distinct zones were identified from the local particle holdup data, with the boundaries corresponding to characteristic jet lengths. Strong discrepancies were found with …

Self-Fluidization Of Fastly-Moving Granular Gravity Currents With Implication On Pyroclastic Flows, Piero Bareschino, Antonio Marzocchella, Piero Salatino, Teresita Gravina, Lucio Lirer, Paola Petrosino

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The fast motion of gravity currents of group A granular solids is studied with a focus on the dynamical structure of the frontal zone. The frontal zone of the current is “immobilized” and observed in a fixed frame of reference by letting the current flow inside a rotary drum, big enough to make curvature effects negligible. The establishment of a variety of flow regimes, including intermittent avalanching, periodic “plunging breaking” and permanent fluidization of the granular solids in the frontal zone, can be related to flow conditions and to the nature of the granular solids.

H2-Rich Syngas From Renewable Sources By Dual Fluidized Bed Steam Gasification Of Solid Biomass, Christoph Pfeifer, Tobias Pröll, Bernhard Puchner, Hermann Hofbauer

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Steam gasification of solid biomass yields high quality producer gases that can be used for efficient combined heat and power production (CHP) and as a renewable resource for chemical syntheses. The dual fluidized bed steam gasification technology provides the necessary heat for steam gasification by circulating hot bed material that is heated in a second fluidized bed reactor by combustion of residual biomass char. The hydrogen content in producer gas of such gasifiers is about 40 vol% (dry basis). Addition of carbonates to the bed material and adequate adjustment of operation temperatures in the reactors allow selective transport of CO2 …

Fluid-Dynamic Investigations In A Cold Model For A Dual Fluidized Bed Biomass Steam Gasification Process: Optimization Of The Cyclone, Andreas Kreuzeder, Christoph Pfeifer, Hermann Hofbauer

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Gasification of biomass is an attractive technology for combined heat and power production. Although a great deal of research and development work has been carried out during the past decade the commercial breakthrough for this technology is still not in sight. The optimisation of the operation costs influences significantly the economic efficiency. Especially bed material consumption constitutes a major part of expenses in fluidised bed systems. Thus, cyclones for circulating fluidized beds need to be designed properly. A dual fluidized bed steam gasifier is in commercial operation at the biomass CHP (combined heat and power plant) in Güssing, Austria since …

Combustion Studies Of Sawdust In A Bubbling Fluidized Bed, K.V.N. Srinivasa Rao

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Biomass fuels are difficult to handle due to high moisture and fines content. In the present work, the effect of secondary air injection on combustion efficiency of sawdust in the fluidized bed combustor has been discussed. An enlarged disengagement section is provided to improve combustion of fines. The maximum possible combustion efficiency with saw dust is 99.2 % and is observed at 65 % excess air.

Authors Index, Xiaotao T. Bi, Franco Berruti, Todd S. Pugsley

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

No abstract provided.

Instrumental Intensity Scales For Geohazards, Steven Kramer, Sarah B. Upsall

Geohazards

The relationship between ground motion characteristics and geohazard-related earthquake damage was investigated for slope instability, lateral spreading, settlement, and buried pipeline damage, and the results used to develop two instrumental intensity scales. The scales are based on three velocity-related ground motion parameters that reflect the amplitude, frequency content, and duration of a ground motion. The scales provide intensity values that are strongly correlated to potential damage – one scale expresses intensity on a 0-10 scale and the other in terms of an apparent earthquake magnitude. The former is expected to be particularly useful for rapid identification of potential damaged areas …

Expected Earthquake Losses To Buildings In Istanbul And Implications For The Performance Of The Turkish Catastrophe Insurance Pool, E. Durukal, M. Erdik, K. Sesetyan

Geohazards

The city of Istanbul will likely experience substantial direct and indirect losses as a result of a future large earthquake. This paper reports on the expected building losses in the city in terms of probable maximum and average annualized losses and discussed the results from the perspective of the compulsory earthquake insurance scheme operational in the country.

Predicting Rainfall-Induced Movements Of Slides In Stiff Clays, Michele Calvello, Leonardo Cascini

Geohazards

A physically-based numerical method is presented for displacements hazard analyses, at large-scale, in the case of landslides characterized by movements along pre-existing slip surfaces induced by rainfall-triggered pore pressure fluctuations. The method comprises a transient seepage finite element analysis and a kinematic model. With reference to the latter, the rates of displacement are assumed to be of the viscous type and are related to the factors of safety along the slip surface computed performing time-dependent limit equilibrium analyses. Monitoring data from an active slide in Central Italy are then used both for calibrating the models, by means of an inverse …

Simulation Of Socio-Economic Impacts Due To Seismic Damage Of Tehran Water Network, Reza Rasti, Farshad Vazinram

Geohazards

In recent years, the massive losses caused due to big earthquakes in urban areas. These cause significant casualties and losses. The economic losses exceed several billions dollars per year. The loss may be categorized in two types of direct and indirect loss. Direct economic losses occur just during the earthquakes or immediately after them. Indirect losses are resulted from direct losses. These losses are obtained in Tehran due to damage of Water Network. A scenario earthquake that would severely damage the city is assumed. The acceleration and velocities are determined in Tehran GIS map. The vulnerability coefficient for pipe via …

Earthquake-Induced Landslides In Colombia, Carlos Eduardo Rodriguez

Geohazards

Landslides due to earthquakes in Colombia have been historically reported since 1530 when ground cracking, soil movements and liquefaction events were induced by an earthquake which magnitude has not been defined. Since then more than thirty earthquakes have been identified to have produced landslides in the country, in some cases consequences related to landslides have been more significant than those due to direct effects of the earthquake itself.

The author has compiled a database of landslides induced by earthquakes in Colombia from which relationships between earthquake magnitude and landslide characteristics have been explored. It has been found that residual and …

The Hazard Assessment In A Terraced Landscape: Preliminary Result Of The Liguria (Italy) Case Study In The Interreg Iii Alpter Project, G. Brancucci, G. Paliaga

Geohazards

In steep areas the lack of terrain suitable to farming has induced man to modify the slopes with terraces. In the ligurian territory (northern Italy) above the twenty per cent of the total surface area have been changed by means of terraces. Terraces may be regarded as a human interference with the geomorphic system, which drives the evolution of the terrestrial surface. This interference actually causes the increase of the hazard particularly in those areas where the morphology hardly constrains the urbanisation. The preliminary results here presented are part of the hazard assessment task of the EU Interreg III Alpter …

Comparison Of Risk Management Policies In Oecd Countries, Reza Lahidji

Geohazards

The Organisation for Economic Cooperation and Development started in 2003 a series of country studies and reviews aimed at assisting its Member countries in evaluating the effectiveness of their risk management systems, notably in terms of their ability to contend with large-scale risks of the future, and at offering them guidance in making the requisite improvements. The project, entitled the OECD Futures Project on Risk Management Policies, focuses on the consistency of risk management policies and on their ability to deal with the challenges, present and future, created by the evolution of the risk landscape.

The Project gathers eight Member …

Cost Evaluation For Traffic And Transport Infrastructure Projects Taking Account Of Project Risks, Rudolf Poettler, H. F. Schweiger

Geohazards

The realisation of large transport infrastructure projects is influenced by a wide range of different factors. The general expectation that a project should be carried out under defined boundary conditions within the planned period and on budget requires a high level of design, planning and controlling. This paper discusses standardised comprehensible fundamental rules and guidelines for defining project costs and project budgets of infrastructure projects taking into account risk assessment and risk management. Adhering to these guidelines and rules contributes to ensure that the structure can be built in the required quality, on schedule and on budget, as well as …

Integrating Physical Accessibility Of Emergency Establishments Into Earthquake Risk Assessment, Kivanc Ertugay, Sebnem Duzgun

Geohazards

Human being has always been in a continual struggle with disasters. They are mostly sudden and unexpected and cause irreversible damages to human life and property. Disasters are facts of life, but it is always possible to decrease the effects of disasters by preparedness. In disaster case, accessibility is one of the most vital and important components of disaster preparedness and mean the difference between loosing a life or saving a life. That is why emergency accessibility, regardless if it is measured in time, distance, population or any other cost, is the most important variable that decision makers must consider …

Integrated Natural Disaster Risk Assessment: The Socio-Economic Dimension Of Earthquake Risk In The Urban Area, Sibel Kalaycioglu, Helga Rittersberger-Tilic, Kezban Celik, Fatime Günes

Geohazards

Understanding and formulation of risk of a natural disaster requires consideration of every aspect of risk, which can be handled by development of integrated approaches. In such integrated approaches, several discipline’s views are incorporated into risk assessment to see the whole picture. Hence, the risk which can be experienced before and / or after a natural disaster should be a common concern for both natural and social disciplines and should be handled through a interdisciplinary approach. A field research was conducted with 1500 households, selected through stratified random sampling, using the database obtained from the Eskisehir Greater Metropolitan Municipality. Interviews …

Dealing With Uncertainty In Engineering Design For Large-Scale Gravel Soil Slopes In The Three Gorges Reservoir Zone, Wilson H. Tang, L. M. Zhang, Y. R. Zheng

Geohazards

The objective of this paper is to first present a general formulation for analysis of uncertainties and evaluation of risks associated with large-scale slopes. The risks may be expressed in terms of the reliability of the system and the consequence. Preliminary studies regarding the mitigation of landslides in the Three-Gorge reservoir zone (TGRZ) of the Yangtze River is presented next. At the normal water level of 175 m, the Three-Gorge reservoir stretches for 665 km along the Yangtze River and extends into many tributaries. Some 684 colluvial deposits, ancient slides and hanging rock blocks, which are larger than 100,000 m3 …

Urban Earthquake Risk, Mustafa Erdik

Geohazards

The impact of earthquakes in urban areas is a complex problem compounded by multi-hazard and consequential risk issues, enormous inventory of vulnerable physical elements and the attendant socio-economic problems. A review of our state-of-knowledge and applications on the assessment of urban earthquake risk is provided. Rational urban risk predictions and expected losses from major earthquakes in the future serve the basis and also provide strong reasons for the proactive risk mitigation activities.

Dam Risk Analysis Using Bayesian Networks, Marc Smith

Geohazards

The risks related to existing hydraulic structures have been analyzed using bayesian networks. The proposed multidisciplinary approach allowed the comparison, according to the probability of failure being used as a common denominator, of the geotechnical, hydrological and structural risks. The factors contributing the most to the overall risk have been identified as well as the interventions to be realized in priority. The presented concepts consider dam risk in a more global and holistic way.

Mapping Expert Uncertainties Or Confidence Level In Mining Risk Prevention Plans, M. Cauvin, T. Verdel, R. Salmon, C. Didier

Geohazards

Mining Risk Prevention Plans have been developed in France in order to deal with “Post-Mining” issues in a rapid and operational way. This inevitably implies that the final result of those risk analyses might contain a significant part of uncertainty. The study presented herein introduces a framework and some tools that allow experts to express the confidence they have in their evaluation and raise the main difficulties they face in their daily work.

Risk Assessment Due To Debris Flows In Paz De Río-Colombia, Carlos Eduardo Rodriguez, O. I. Chaparro, G. Flechas

Geohazards

Paz de Río is an important economic area of Colombia where iron mines produce most of the mineral for the steel production in the country. Along the La Chapa creek some debris flows have occurred since 1963 producing economic losses and human deaths at Santa Teresa village. Economical losses are related to disruption of the main access to La Chapa iron mine facilities, and flooding of Paz de Río due to damming of Chicamocha River, the main drainage system of the region, which is blocked by debris flows.

The local authority for Natural Disaster Management (CREPAD) jointly with the Universidad …

Landslide Hazard Assessment At “Sakhalin-2” Main Pipeline Project, S. I. Matsiy, A. P. Sheglov, D. V. Pleshakov

Geohazards

In the given article, 2 various approaches to a landslide hazard assessment are considered. Landslide hazard means probability of a slope failure. The calculations have been carried out using a landslide hazardous section of Sakhalin-2 main pipeline route as an example.

Influence Of Degrading Permafrost On Landsliding Processes: Little Salmon Lake, Yukon Territory, Canada, R. Lyle, D. Jean Hutchinson

Geohazards

A landslide inventory was carried out for the Little Salmon Lake area, Yukon Territory, Canada, in response to observations of several new landslides in the area, suspected to be the result of degrading permafrost. The largest of these landslides, the Magundy River bi-modal flow-slide, has progressed over the last decade until it now involves over 1x106 m3 of material. The inventory is based on terrain mapping and field work, and includes multiple landslide types. The field work provided the opportunity to examine the slides, ground truth the map, and to examine the progression of the landslide, as well as the …

Age Dating Of Karst Forms Upon Regional Assessment Of Karst Hazard (A Case Study Of The Tatarstan Republic, Russia), V. A. Yolkin

Geohazards

The detailed investigations accompanied by collection of forty samples for radiocarbon and palynological analyses from six poorly and well-marked in a relief karst and karst-suffosion sinkholes, have shown, that the largest of them (diameter more than 30 m) are up to 5 - 10 thousand years, and the smaller size up to 2 - 3 thousand years. The marked karst forms - lakes, hollows and the depression reaching in diameter 200 - 300 m and more, were formed due to merging of separate forms and, most likely, have a long pre-Holocene history. The general procedure of regional probabilistic-deterministic assessment of …

Warning System For Natural Threats, Herbert Einstein, R. Sousa

Geohazards

Warning systems are an essential component of risk management for natural threats. They trigger active and/or passive countermeasures. This paper introduces the need for and use of warning systems through the review of recent major natural disasters (the Sumatra Tsunami, the 2005 Alpine Flood, the 2005 Hurricanes, Katrina and Rita) but also the potential flu pandemic. Positive and negative lessons are drawn from these cases. This is followed by a review of two specific warning systems which together with the preceding cases leads to a list of requirements for warning systems.

These reviews also show that it is desirable to …

On The Acceptable Risk For Structures Subjected To Geohazards, D. Diamantidis, S. Duzgun, F. Nadim, M. Wöhrle

Geohazards

Geohazards such as earthquakes or landslides represent a major risk to structures. In this contribution risk acceptance criteria for structures subjected to geohazards are reviewed. Especially the implementation of human safety and cost benefit considerations are discussed. Current trends in the definition of target safety criteria for structures subjected to earthquakes and landslides are presented and conclusions regarding codified criteria are drawn.

Evaluation Of Liquefaction Susceptibility For Microzonation And Urban Planning, Atilla Ansal, Gokce Tonuk

Geohazards

Various procedures were developed to evaluate liquefaction susceptibility of soil layers for implementing engineering remediation measures. The approach that has gained wide acceptance within the framework of urban planning is to establish microzonation maps with respect to liquefaction susceptibility to mitigate possible earthquake damage related to liquefaction. In this context, microzonation maps were produced recently for six municipalities in Turkey as a part of a major Pilot Project. Two variables are required for the assessment of liquefaction resistance of sandy soil layers; the seismic demand expressed in terms of cyclic stress ratio, CSR; and the capacity of the soil layers …

Instrumentation Of Flexible Buried Culvert Subjected To Rockfall Loading, R. Ebeltoft, J. O. Larsen, S. Nordal

Geohazards

Natural hazards, like avalanches and rock falls, will always be a major concern for infrastructure, i.e. roads and railways, in mountain areas. Several measures are available to protect this infrastructure, but especially in areas with steep slopes, rockfall- or avalanche galleries are commonly used. These structures, which are made to withstand high impact forces, can be made of reinforced/pre-stressed concrete culverts covered with soil. A possibly cheaper and equally safe alternative could be to use a buried corrugated steel culvert.

To investigate the use of buried corrugated steel culverts as rock fall protection structures an experimental study has been carried …

The Importance Of Laboratory Experiments In Landslide Investigation, Barbara Schneider-Muntau, D. Renk, T. Marcher, Wolfgang Fellin

Geohazards

This study focuses on a better understanding of mass movements and on the influences of different boundary conditions on velocities of creeping slopes. A well monitored example of a slowly creeping landslide is the mass movement Hochmais - Atemkopf, situated in the Kaunertal, Tyrol, Austria (Fig. 1). The long term monitoring program for more than 40 years of this landslide gives a good impression of its time dependent behaviour. A large amount of additional data, as geological mapping, boreholes, geophysical investigation and so on provides a funded base for the model’s geometry. The most influencing factor for finite element …