bluuebunny/crossref_metadata_2025 huggingface dataset:
Validation of a Brief Self‐Administered Questionnaire for Cluster Headache Screening in a Tertiary Center
Authors: Dousset Virginie , Laporte Alain , Legoff Mélanie , Traineau Marie‐Hélène , Dartigues Jean‐François , Brochet Bruno
Published: January 2009

Background.— Cluster headache remains substantially underdiagnosed and undertreated. Early neurologic referral is indicated in patients with a suspected diagnosis of cluster headache (CH) so that management can be optimized and unnecessary procedures avoided.

Objective.— To validate a brief self‐administered questionnaire designed to screen CH cases in tertiary centers.

Methods.— The review of clinical studies led us to identify the 3 more prevalent criteria of the second edition of the International Headache Society classification (International Classification of Headache Disorders, 2nd edition [ICHD II]) for all forms of CH (episodic and chronic forms). These 3 criteria were: strictly unilaterality of pain, attack duration <180 minutes if untreated, ipsilateral conjunctival injection, and/or lacrimation. These criteria were transformed in questions formulated in such a way that they could be self‐administered and easily understood. Answer to each question was yes or no. Patients were unaided. The self‐questionnaire was compared with the gold standard, the ICHD II criteria used by specialists at the university of Bordeaux headache center. We calculated the sensitivity and specificity for the 3 questions and for each pair of questions.

Results.— The self‐questionnaire was consecutively and prospectively submitted to 37 patients with CH and 59 patients with migraine. The 3‐item questionnaire had a 78.4% sensibility and a 100% specificity. The 2‐item questionnaire only using the attack duration associated with conjunctival injection and/or lacrimation was more sensitive (81.1%) with the same specificity (100%).

Conclusions.— This 2‐item questionnaire could be a useful tool for screening CH cases in tertiary centers.
Exploring Home Allodynia Testing For Future Clinical and Scientific Uses
Authors: Madden Timothy , Rosen Noah , Young William
Published: January 2009

Allodynia, a painful response to a usually nonpainful stimulus, is common in chronic migraine. The evaluation of allodynia can be important clinically. Dynamic mechanical allodynia (brush) testing has been shown to be both a simple and reliable way to evaluate allodynia. In this study, we show that self‐administered brush allodynia testing at home is a feasible means of evaluating and recording allodynia in relationship to chronic migraine.
Development and Construct Validation of the Pharmacists' Care of Migraineurs Scale
Authors: Skomo Monica L. , Desselle Shane P. , Shah Neel
Published: January 2009

Objectives.— To develop the pharmacists' care of migraineurs scale (PCMS) and to evaluate its psychometric properties.

Background.— Migraine is often managed suboptimally in primary care. Migraineurs frequently come into contact with community pharmacists, who have the opportunity to make a positive impact on migraineur treatment outcomes. A valid and reliable tool that measures and documents the care provided by pharmacists to migraineurs is critical to the development and evaluation of educational programs and interventions.

Methods.— Relevant domains of pharmacist care and their respective composite items (behaviors) were identified through an extensive literature search and the use of 2 pharmacist and 2 migraineur focus groups sessions. The resultant 45 PCMS items composed a survey questionnaire mailed to a nationwide random sample of 6000 pharmacists. Data were subjected to an exploratory principal axis factoring procedure to discern the factor structure, and as such describe the latent domains composing the pharmacist caring behaviors constructs.

Results.— A total of 580 usable responses were returned, with an additional 60 returned as undeliverable, thus yielding a response rate of 9.7%. Exploratory factor analysis using principal axis factoring yielded 9 factors. However, upon examining the scree plot, communalities, and factor loadings, a reanalysis forcing a 7‐factor solution yielded a more interpretable and plausible factor structure. The 7‐factor solution included the following domains: (1) empathy; (2) prospective drug utilization review for newly diagnosed migraineurs; (3) medication counseling; (4) nonpharmacologic treatment plan; (5) headache sufferer triage; (6) dissemination of public health information; (7) maintenance of knowledge on migraine. Following the application of scale purification procedures, the final instrument is composed of 41 items and demonstrated a Cronbach's alpha reliability of 0.947. Cronbach's alpha reliabilities for the 7 domains ranged from 0.67 to 0.91, indicative of good to excellent internal consistency reliabilities for all the domains.

Conclusions.— The PCMS demonstrated very good construct validity and reliability. While additional validity testing is warranted, the PCMS should allow for benchmarking in the evaluation of interventions designed to improve pharmacists' care to migraineurs and for identifying correlates to effective community pharmacist migraineur care.
Designs for Detecting Spatial Dependence
Authors: Gumprecht Daniela , Müller Werner G. , Rodríguez‐Díaz Juan M.
Published: January 2009

The aim of this article is to find optimal or nearly optimal designs for experiments to detect spatial dependence that might be in the data. The questions to be answered are: how to optimally select predictor values to detect the spatial structure (if it is existent) and how to avoid to spuriously detect spatial dependence if there is no such structure. The starting point of this analysis involves two different linear regression models: (1) an ordinary linear regression model with i.i.d. error terms—the nonspatial case and (2) a regression model with a spatially autocorrelated error term, a so‐called simultaneous spatial autoregressive error model. The procedure can be divided into two main parts: The first is use of an exchange algorithm to find the optimal design for the respective data collection process; for its evaluation an artificial data set was generated and used. The second is estimation of the parameters of the regression model and calculation of Moran's I, which is used as an indicator for spatial dependence in the data set. The method is illustrated by applying it to a well‐known case study in spatial analysis.
Cost‐efficient Reserve Site Selection Favoring Persistence of Threatened and Endangered Species
Authors: Hamaide Bertrand , Williams Justin C. , ReVelle Charles S.
Published: January 2009

This article formulates and tests set covering and related models with spatial characteristics for selecting sites that provide habitat for species that are identified as “critical” (e.g., typically threatened, endangered, or rare), thereby enhancing their persistence. The first two models presented require the creation of a core area for each critical species and a buffer zone surrounding the core, with and without being constrained to include at least one representation of each and every common (i.e., noncritical) species. The final model aims at minimizing costs of protecting predetermined numbers of common species while all critical species remain covered and buffered. These models are implemented for occurrence data of terrestrial mammals in Oregon. They enable, among other things, a comparison between the budgetary impacts of reserve networks with and without buffering rings for critical species, and a determination of the marginal cost of common species protection.
Computational Comparison of Five Maximal Covering Models for Locating Ambulances
Authors: Erkut Erhan , Ingolfsson Armann , Sim Thaddeus , Erdoğan Güneş
Published: January 2009

This article categorizes existing maximum coverage optimization models for locating ambulances based on whether the models incorporate uncertainty about (1) ambulance availability and (2) response times. Data from Edmonton, Alberta, Canada are used to test five different models, using the approximate hypercube model to compare solution quality between models. The basic maximum covering model, which ignores these two sources of uncertainty, generates solutions that perform far worse than those generated by more sophisticated models. For a specified number of ambulances, a model that incorporates both sources of uncertainty generates a configuration that covers up to 26% more of the demand than the configuration produced by the basic model.
Endemic measles in Karachi, Pakistan and validation of IMCI criteria for measles
Authors: Hussain Hamidah , Omer Saad B , Khan Aamir J , Bhurgri Ahsan , Memon Ashraf , Halsey Neal A
Published: January 2009

Aim: To estimate the incidence of measles in Karachi, Pakistan and to determine the proportion of children with measles based on the WHO integrated management of childhood illness (IMCI) criteria with a positive IgM for measles or dengue.

Methods: Patients up to 14 years old were screened for febrile rash illnesses at five Karachi hospitals. Active measles cases were classified as measles, measles with eye and mouth complications, or severe complicated measles using IMCI criteria.

Results: Screening 1 219 061 patients over a 39‐month period identified 3503 qualified children. Most (76.8%) measles cases occurred in children under five years of age. The average annual incidence rate was 0.68 per 1000 in year 1; 0.19 in year 2 and 0.08 in year 3 of surveillance. Pneumonia and diarrhoea were the most common complications. Of 18.1% hospitalized, 1.6% died. Of 2286 children tested, 1599 (69.9%) were measles IgM positive. Of 542 measles IgM negative children, 66 (12%) were dengue IgM positive. The predictive positive value for the IMCI case definition was 75%.

Conclusion: The IMCI case definitions for measles is reasonable but may overestimate measles incidence. Measles continues to be a public health problem in Pakistan; increased efforts to control measles are urgently needed.
Breast‐feeding and a subsequent diagnosis of measles
Authors: Silfverdal SA , Ehlin A , Montgomery SM
Published: January 2009

Background: Breast‐feeding protects against many infectious diseases and may also influence immunization outcomes.

Aim: This study investigated if breast‐feeding protects against clinical measles and if it modified the effect of immunization.

Methods: We used logistic regression with data for 10 207 individuals from the 1970 British Cohort study (BCS70). Breast‐feeding data were collected at five years of age, and information on clinical measles infection, as well as socio‐economic measures was collected at the age of ten years. Breast feeding was categorized as: breast‐fed <1 month (n = 1611), breast‐fed for 1–3 months (n = 1016), breast‐fed for more than three months (n = 1108), breast‐feeding of uncertain duration (n = 21) and never breast‐fed (n = 6451).

Results: Breast‐feeding for more than three months was negatively associated with a diagnosis of clinical measles infection after adjustment for crowding, social class, measles vaccination, parity and sex with an odds ratio (95% confidence interval) of 0.69 (0.60–0.81) compared with those who never breast‐fed. Measles vaccination was highly associated with low risk for measles with: 0.14 (0.13–0.16). Age at acute measles infection was not associated with breastfeeding. Breast‐feeding did not notably alter measles immunization efficacy.

Conclusion: Immunization against measles provides effective protection against the disease. A more modest reduction in the risk of a measles diagnosis is associated with breast‐feeding. The associations with a diagnosis of measles for breast‐feeding and measles immunization are independent of each other.
Women's experiences of infant feeding support in the first 6 weeks post‐birth
Authors: Sheehan Athena , Schmied Virginia , Barclay Lesley
Published: January 2009

Research suggests women find the first 2 to 6 weeks to be the most difficult time for breastfeeding. It has been identified that women need and seek support with breastfeeding during this time. Support is a difficult concept to define. When discussed by professionals, support for breastfeeding is generally viewed in terms of providing information and educational interventions. There is little understanding of the different elements of breastfeeding support strategies and the mechanisms by which support operates. Further, there is a paucity of qualitative research specifically reporting women's experiences and expectations of professional support. This paper describes women's expectations and experiences of ‘infant feeding support’ provided by health professionals in the first 6 weeks post‐birth. The findings are drawn from a grounded theory study exploring women's infant feeding decisions in the first 6 weeks post‐birth. Participants were recruited from a variety of socio‐demographic areas of Sydney and the NSW Central Coast, Australia in 2003–2004. The women in this study discussed aspects of what they considered helpful and/or unhelpful in terms of professional support. In addition, they also provided insight into aspects of interactions that were deemed important to them as new mothers learning to feed their babies. The results are presented in three sections: expecting support, experiencing support and evaluating support. The findings help to better understand components of professional practices and behaviours that can be considered supportive. The support behaviours are far more complex than simply increasing education and knowledge of infant feeding. They demonstrate the need for sensitive individualized care and show that this type of support can increase women's confidence to breastfeed.
Discriminatory predation by three invertebrates on eastern oysters (Crassostrea virginica) compared with non‐native Suminoe oysters (C. ariakensis)
Authors: Kennedy Victor S. , Shaw Kristi S. , Newell Roger I.E.
Published: January 2009

Abstract. Diminished populations of eastern oysters Crassostrea virginica in Chesapeake Bay have stimulated proposals to introduce Crassostrea ariakensis from Asia to restore oyster stocks. As part of a program evaluating possible ramifications of such an introduction, we studied how invertebrate predators responded to this non‐native oyster. We compared predation activity under laboratory conditions by oyster drills (Urosalpinx cinerea; Eupleura caudata) that bore through an oyster's shell and by the seastar Asterias forbesi that pulls shell valves apart. These three predators preyed significantly (p<0.05) more on the familiar C. virginica than on the novel C. ariakensis. We previously reported that five crab species preyed significantly more on C. ariakensis than on C. virginica, with predation by polyclad flatworms similar between oyster species. Thus, the drills and the seastar differed from the crabs and the flatworms in their response to novel prey. When Urosalpinx cinerea was placed in a Y‐maze after being held for 40 d with oysters of one species or the other, the drills moved toward C. virginica effluent more than toward C. ariakensis effluent. This response did not depend on the species of oyster the drills had been held with, suggesting that the drills were responding to more familiar infochemicals from eastern oysters than from the non‐native oysters.
Microsatellite inheritance and multiple paternity in the deep‐sea octopus Graneledone boreopacifica (Mollusca: Cephalopoda)
Authors: Voight Janet R. , Feldheim Kevin A.
Published: January 2009

Abstract. Octopodids are a globally distributed group of marine molluscs. Despite this, our knowledge of their reproductive biology rests heavily on inference, as all phases of copulation, beginning with sperm transfer, occur within the mantle cavity. Male octopuses insert a spermatophore into the female's oviduct, which is predicted to release a sperm‐filled sac that either bursts to release sperm for storage or to itself be stored in a gland in the middle of the oviduct. To test whether female octopuses use sperm from multiple males to fertilize their eggs, as may be predicted from anatomy and anecdotal accounts, we apply microsatellite analysis to a partial clutch of Graneledone boreopacifica collected at 1600‐m depth to test for multiple paternity. At least two genetically distinct sires contributed sperm to the hatchlings analyzed, demonstrating for the first time multiple paternity in octopodids.
Ascidian tunic cells: morphology and functional diversity of free cells outside the epidermis
Authors: Hirose Euichi
Published: January 2009

Abstract.Tunic cells are free cells distributed in the tunic, the integumentary matrix of tunicates. In ascidians, various types of tunic cells have been described both in solitary and in colonial species. Many of them are functionally specialized and are related to the protection of the animal, such as phagocytosis to prevent infection, acid storage to avoid predation, and pigmentation to protect against solar radiation. While some tunic cells are known to play a role in colonial allorecognition, bioluminescence, and algal symbiosis, the functional roles of many cell types still remain to be determined. The composition of tunic‐cell types varies among ascidian species, most likely reflecting the functional requirements of the tunic in each species. Although some cell types, e.g., tunic net cells and tunic bladder cells, are restricted to particular taxa of ascidians, tunic phagocytes are found in all known ascidians. Therefore, tunic phagocytes are hypothesized to be basal and shared with ancestral tunicates. In some ascidians, phagocytic cells are involved in other functions, such as pigmentation, intracellular photosymbiosis, and bioluminescence. These specialized phagocytic cells are hypothesized to be derived from tunic phagocytes, suggesting that tunic cells have a high potential to diversify and evolve a wide variety of cellular functions.
Personal digital assistant use by nurse practitioners: A descriptive study
Authors: Stroud Sally D. , Smith Carol A. , Erkel Elizabeth A.
Published: January 2009

Purpose:We sought to describe the prevalence and patterns of use of personal digital assistants (PDAs) among active nurse practitioners (NPs).

Data sources:A descriptive correlational survey was conducted among NPs in the United States (N= 126). Participants were randomly selected from members of the American Academy of Nurse Practitioners who had listed a practice site on their application.

Conclusions:Sixty‐four percent of participants used PDAs. A drug reference was reported to be the most useful and frequently installed application. A large majority of PDA users believed that PDA use supported clinical decision making (91%), promoted patient safety (89%), and increased productivity (75%). Sixty‐two percent predicted that PDA use would change their practice within the next 5 years.

Implications for practice:As innovative PDA applications with potential to improve patient outcomes become increasingly available, handheld computer skills will be a fundamental practice competency. To prevent errors in clinical decision making with quick access to PDA reference materials, NPs must critically evaluate the legitimacy and worth of PDA software programs. There is a critical need to evaluate the effectiveness of PDA use in clinical settings and develop an evidence base to guide use of the PDA in solving clinical problems.
Management of asthma: New approaches to establishing control
Authors: Sarver Nancy , Murphy Kevin
Published: January 2009

Purpose: The high burden of asthma indicates suboptimal control of this chronic condition. This review describes approaches for establishing asthma control based on an understanding of potential issues in the achievement and maintenance of asthma control, recent changes in asthma management guidelines that facilitate attainment of treatment goals, and the importance of the healthcare provider‐patient partnership to emphasize treatment based on asthma control.

Data sources: Review of the published literature, asthma management guidelines, and patient asthma education resources.

Conclusions: Asthma control is best achieved by patient‐oriented versus disease‐oriented management strategies that incorporate a combination of pharmacologic and nonpharmacologic treatment modalities. Tools that assess and monitor asthma may facilitate the achievement and maintenance of asthma control. Key components of an optimal management strategy include solid partnerships between healthcare providers and patients, comprehensive patient and caregiver education, personalized written asthma action plans, patient‐reported evaluation of symptom control, appropriate drug therapy, strategies for improving compliance with asthma medication regimens, and a treatment algorithm that outlines the facets of asthma management.

Implications for practice: Information presented in this article will guide nurse practitioners in helping patients with asthma achieve and maintain long‐term disease control.
Altered Molecular Weight Forms of Adiponectin in Hypertension
Authors: Baumann Marcus , Von Eynatten Maximilian , Dan Liu , Richart Tom , Kouznetsova Tatiana , Heemann Uwe , Staessen Jan A.
Published: January 2009

An important link between adiponectin and hypertension has been proposed in clinical studies. In the circulation, adiponectin is predominantly present in multimeric complexes, of which high–molecular weight (HMW) adiponectin is thought to represent the biological active form. The authors investigated which role the different multimeric adiponectin isoforms play in context with hypertension as compared to total adiponectin levels. Fifty (19 normotensive/31 hypertensive) patients were included in the study. Total adiponectin and adiponectin multimers were determined by enzyme‐linked immunosorbent assay and western blot. The authors analyzed associations between adiponectin multimer levels and blood pressure. Total adiponectin concentrations were not significantly different between hypertensive and normotensive patients (6.8±2.3 vs 7.5±4.2 μg/mL). HMW adiponectin was significantly lower (P<.05) and low–molecular weight adiponectin was significantly higher (P<.01) in hypertensive than in normotensive persons (3.8±1.7 vs 5.2±3.0 μg/mL and 0.9±0.5 vs 1.8±0.9, respectively). Low molecular weight was an independent predictor for the presence of hypertension (effect coefficient: 0.160–0.445; P<.001) in multivariate analyses. These results suggest that the composition of the molecular weight forms of adiponectin in hypertension are characterized by reduced HMW adiponectin, the proposed major active form of adiponectin, and increased low–molecular weight adiponectin. Moreover, the latter represents an independent predictor of prevalent hypertension, suggesting an association between adiponectin multimer composition and hypertension.
GGR Biennial Review: Advances in Geo‐SIMS during 2006–2007
Authors: Wiedenbeck Michael
Published: January 2009

Secondary ion mass spectrometry (SIMS or ion microprobe) remains one of the most powerful tools available to the analytical geochemist. Despite the impressive progress witnessed by other competing laboratory methods over recent years, SIMS remains unsurpassed in its combination of small sampling volumes with low analytical uncertainties. Although the current SIMS analytical design has existed for over three decades, the period 2006–2007 saw significant advances in instrumentation, analytical methodology and, not least, the characterisation of new reference materials upon which all analyses depend. As of the end of 2007 the SIMS geoscience literature was reporting total sampling masses down to the 10 fg range, spatial resolution of better than 100 nm and uncertainties on major element isotope ratio determinations of better than ± 0.2‰ (1s). This article intends to synthesise the progress made by the geo‐SIMS community during this two year period and will also highlight some specific research results that were only possible due to the unique capabilities provided by SIMS.
ANOREXIA NERVOSA AND THE PSYCHOTHERAPY OF ABSENCE
Authors: Winston Anthony P.
Published: January 2009

abstract  Absence is characteristic of the psychotherapy of many different types of psychological disorder. However, it is perhaps particularly significant in the psychotherapy of anorexia nervosa. I hope to show that the notion of absence can help to draw together some of the many strands which go to make up this most complex of conditions. Recognition of what is absent can help illuminate the patient's unconscious conflicts and point to the capacities that she has been unable to develop. These absences arise out of early environmental deficiencies, such as a lack of containment, which can result in failures of introjection and an absence of the potential space. They can leave the child ill equipped to experience, understand or deal with her feelings, develop a secure sense of self or think symbolically. Sexual desire, aggression and envy often appear to be absent from the conscious world of the anorexic. In therapy, there is often a striking absence of feeling and of connection between patient and therapist. The work is done largely in relation to what is not talked about, felt or understood and what is apparently not happening. The therapist needs to create a space in which absence and emptiness can be thought about and symbolized, and a sense of self can begin to develop.
A Microscopic Approach to Determine Electrothermal Contact Conditions During Resistance Spot Welding Process
Authors: Rogeon P. , Raoelison R. , Carre P. , Dechalotte F.
Published: January 2009

This study deals with resistance spot welding process modeling. Particular attention must be paid to the interfacial conditions, which strongly influence the nugget growth. Imperfect contact conditions are usually used in the macroscopic model to account for the electrical and thermal volume phenomena, which occur near a metallic interface crossed by an electric current. One approach consists in representing microconstriction phenomena by surface contact parameters: The share coefficient and the thermal and electrical contact resistances, which depend on the contact temperature. The aim of this work is to determine the share coefficient and the contact temperature through a numerical model on a microscopic scale. This surface approach does not make it possible to correctly represent the temperature profiles, with the peak temperature, observed in the immediate vicinity of the interface and thus to define, in practice, the contact temperature correctly. That is why another approach is proposed with the introduction of a low thickness layer (third body) at the level of the interface the electric and thermal resistances of which are equivalent to the electrical and thermal contact resistance values. In this case, the parameters of the model are reduced to the thickness of the arbitrarily fixed layer and equivalent electric and thermal conductivities in the thin layer, the partition coefficient and the contact temperature becoming implicit. The two types of thermoelectric contact models are tested within the framework of the numerical simulation of a spot welding test. The nugget growth development is found to be much different with each model.
Design and Commissioning of the Largest and the Smallest Fluidized Bed Incinerator Ever Built by Lurgi
Authors: Huenchen H. , Pachmayer L. , Malerius O.
Published: January 2009

Since communities and companies are deciding to dispose sludges of different origin in a safe and nonpolluting way, more and more sludge is burnt either in mono-combustion or co-combustion units. Lurgi Energie und Entsorgung GmbH, one of the most experienced fluidized bed designer, is commissioning two bubbling bed incinerators of totally different incinerator size in 2002. In France the smallest fluidized bed incinerator ever built by Lurgi with a cross-sectional bed area of 4 m2 is designed to burn 750 kg (d.m.)/h sewage sludge. In spite of the small size it consists of all equipment necessary for sewage sludge incineration, including a disc dryer, a thermal oil boiler for heat recovery and a complete state of the art flue gas cleaning system. Air pollutants are removed in a circulating fluidized bed adsorber (CFB) designed in accordance with the new Lurgi CIRCOCLEAN® process. In United Kingdom the largest bubbling bed incinerator ever built by Lurgi with a cross-sectional bed area of 32 m2 is going to start its operation in 2002. The plant burns a mixture of thickened and mechanically dewatered primary and secondary sludge and different plastic residues from waste paper recycling plants. In order to provide sufficient disposal capacity of the waste material generated at the Kemsley Paper Mill site some parts of the installation consist of parallel streams or units (e. g. waste material handling and storage). The overall design throughput rate of mixed waste material is 22.8 t(a.r.)/h, corresponding to a thermal load of 29.1 MW. Due to the specific properties of the paper sludge, the formed ash can be used as an adsorbent/reactive compound for the capture of acidic pollutants. The flue gas cleaning system consists of a zeolite dosing unit to remove dioxins/furanes upstream of a baghouse filter. The paper presents the main design parameters of both disposal facilities and peculiarities of the burnt materials in comparison to other sludges. Since the plants are still in the commissioning phase only problems that might occur during the operation of the plant and tendencies in the operation behavior are described.
The Mapping of Flow Regimes for a Light Material: Cork
Authors: Mei Joseph S. , Monazam Esmail R. , Shadle Lawerence J.
Published: January 2009

A series of experiments was conducted in the 0.3-meter diameter circulating fluidized bed test facility at the U.S. Department of Energy’s National Energy Technology Laboratory (NETL). Cork, the bed material used in this study, is a coarse, light material, with a particle density of 189 kg/m3 and a mean diameter of 1007 μm. Fluidizing this material in ambient air provides approximately the same gas to solids density ratio as coal and coal char in a pressurized gasifier. Furthermore, the density ratio of cork to air under ambient conditions is similar to the density ratio of coal to gas at the gasification and pressurized fluidized bed combustion environment. The purpose of this study is to generate reliable data to validate the mathematical models currently under development at NETL. Using such coarse, light material can greatly facilitate the computation of these mathematical models. This paper presents and discusses data for the operating flow regimes of dilute-phase, fast-fluidization, and dense-phase transport by varying the solid flux (Gs) at a constant gas velocity (Ug). Data are presented by mapping the flow regime for coarse cork particles in a ΔP/ ΔL-Gs-Ug plot. The coarse cork particles exhibited different behavior than the measurements on heavier materials found in published literature, such as alumina, sand, FCC, and silica gel. Stable operation can be obtained at a fixed riser gas velocity that is higher than the transport velocity (e.g. at Ug = 3.2 m/sec), even though the riser is operating within the fast fluidization flow regime. Depending upon the solid influx, the riser can also be operated at dilute-phase or dense-phase flow regimes. Experimental data were compared to empirical correlations in published literature for flow regime boundaries, and solid fractions in the upper-dilute and the lower-dense regions of a fast fluidization flow regime. Comparisons of measured data show rather poor agreement with these empirical correlations. Xu et al. (2000) have observed this lack of agreement in their study of the effect of bed diameter on the saturation carrying capacity. The basis of empirical correlations depends on bed diameter and particle type, and are generally not well understood.
Combustion Characteristics of Natural Gas in a Circulating Fluidized Bed
Authors: Lu Dennis Y. , Anthony Edward J.
Published: January 2009

Recently there has been interest in extending the application of fluidized bed combustors (FBCs) to fuels with difficult handling properties or ones that are associated with non-conventional air pollutant problems. These fuels, such as biomass, plastic wastes, black liquors and heavy liquid fuels, have very high volatiles contents and, because they are often treated as easily-burned materials, they have received much less attention than has been given say to the combustion processes for char in FBCs. Understanding their gas-phase chemistry is helpful in optimizing their combustion. This paper describes the study of natural gas combustion in a fluidized bed as a simple model for studying gas-phase reactions involving C/H/N/O chemistry in the absence of char. The experimental work was conducted using a pilot-scale CFBC unit. Combustion characteristics and emissions were investigated by varying the operating conditions and in particular the combustion temperature, fluidizing velocity and bed material. The results indicated that fluidized bed combustion chemistry is associated with superequilibrium free radical processes, similar to high-temperature flame systems. In this system, prompt-NO mechanisms are the only routes for NO formation and this work shows that they can lead to significant NOx production.
Lignite-Fired Combined Cycle Power Plant With ACPFBC: Concept and Thermodynamic Calculations
Authors: Krautz Hans Joachim , Chalupnik Rolf , Stuhlmu¨ller Franz
Published: January 2009

A 200 kWth test plant was constructed by BTU Cottbus for the purpose of developing a special variant of coal conversion based on 2nd generation PFBC. This concept, primarily to be used for generating power from lignite, employs a circulating type fluidized bed and is characterized by a design that combines the two air-blown steps “partial gasification” and “residual char combustion” in a single component. The subject of this paper is to develop an overall power plant concept based on this process, and to perform the associated thermodynamic calculations. In addition to the base concept with one large heavy-duty Siemens gas turbine V94.3A fired with Lausitz dried lignite (19% H2O), further versions with variation of Siemens gas turbine model (V94.3A and V64.3A), the water content of the fuel fired (raw lignite with more than 52% H2O or dried lignite) as well as the method of drying the coal were investigated. Common assumptions for all versions were ISO conditions for the ambient air and a condenser pressure of 0.05 bar. As expected, the calculations yielded very attractive net efficiencies of almost 50% (LHV based) for a variant with the small V64.3A gas turbine and up to more than 55% for the large plants with the V94.3A gas turbine. It was further demonstrated that thermodynamic integration of an advanced, innovative coal drying process (e.g. fluidized-bed drying with waste heat utilization) causes an additional gain in net efficiency of about three percentage points compared with the variant of firing lignite that was first dried externally. In addition to the basic function of the coal conversion system, it was necessary to also assume preconditions such as complete carbon conversion, reliable hot gas cleaning facilities and fuel gas properties that are acceptable for combustion in the gas turbine. Put abstract text here.
Producer Gas Cleaning Techniques
Authors: Kandassamy K. , Natarajan E. , Renganarayanan S.
Published: January 2009

This paper reviews various producer gas cleaning techniques developed/ applied in different biomass gasification processes. It investigates various methods for the removal of particulate matter and tar emissions from producer gas generated by various types of gasifiers. The various tar measurement protocols are inconsistent on the definition of tar and particulate matters. The producer gas if used for power generation using IC engines should be less than 50 mg/Nm3, and in the case of gas turbines a minimum particulate matter concentration of 10 ppm (weight) is needed. To control tars and particulates, various insitu (catalytic tar cracking using Dolomite/Nickel, partial oxidation, high temperature tar cracking, biomass selection, two stage gasification) and post gasification treatments (sand bed filter, wash tower, venturi scrubber, rotational atomizer, electrostatic precipitator, fabric filter, fixed bed tar adsorber, catalytic tar cracker, ceramic filter, cyclones etc) are used. In the cleaning train, collection efficiencies decrease drastically as particulate sizes fall below 1.5 μm. Heavy tar and alkali metals cause engine cylinder deposition and high temperature corrosion of turbine blades respectively. The selection of suitable biomass can improve the quality of gas. Nearly every biomass has a high percentage (60–80%) of Tar Forming Particles (PTFV). Tar is a general nomenclature for a group of compounds like phenols, Poly Aromatic Hydrocarbons (PAH), high Molecular Organic Compounds, Water-soluble organic compounds and ash particles agglomerated with organic compounds. It is easier to remove 90% particulate matter than to achieve 90% tar reduction as they form stable aerosols. A combination of insitu and post gasification treatments is necessary to condition the fuel gas for various power generating equipments. Hence, the analysis of various gas cleaning methods are important for applying them in suitable systems.
Modelling Fuel and Sorbent Attrition During Circulating Fluidized Bed Combustion of Coal
Authors: Barletta D. , Marzocchella A. , Salatino P. , Kang S. G. , Stromberg P. T.
Published: January 2009

A simulation model of a circulating fluidized bed combustor, based on a one-dimensional description of bed hydrodynamics and a simplified formulation of the population balance equation on fuel and bed solids, has been set up. The model specifically aims at assessing the extent of fuel and sorbent attrition during circulating fluidized bed combustion of coal. Fuel attrition is modelled as a function of carbon loading and of the relevant operating variables while taking into account primary fragmentation of coal and secondary fragmentation and attrition by surface wear of its char. Modelling of sorbent attrition accounts for primary fragmentation of limestone upon calcination as well as attrition by surface wear of lime. To this end time- and conversion-dependent attrition rate is averaged over the sorbent particle lifetime in the reactor. Attrition submodels and their constitutive parameters are based on previous work by the research group in Naples. Coal char combustion and lime sulphation are modelled considering intrinsic reaction kinetics as well as boundary layer and intraparticle diffusion of reactants. The impact of attrition phenomena on the performance of the fluidized bed combustor is characterized by looking at carbon combustion efficiency, at sulphur capture efficiency, at the balance between bottom and fly ashes. The influence of operating parameters like fuel particle size, Ca/S ratio, gas superficial velocity, extent of air staging is investigated. The sensitivity of results of model computations to the parameters expressing fuel and sorbent attrition is presented and discussed.
Capture of Alkali Metals by Kaolin
Authors: Tran Khanh-Quang , Iisa M. Kristiina , Steenari Britt-Marie , Lindqvist Oliver , Hagstro¨m Magnus , Pettersson Jan B. C.
Published: January 2009

Alkali metals present in biomass fuels may cause increased bed agglomeration during fluidized bed combustion. In worst case this may lead to complete defluidization of the bed. Other problems caused by alkali metals include increased fouling and slagging. One possibility to reduce the impact of alkali metals is to add sorbents, e.g. aluminosilicates, to the bed for the capture of alkali metals. In the current investigation, the capture of vapor phase potassium compounds by kaolin was investigated in a fixed bed reactor. The reactor consisted of an alkali metal source placed at a variable temperature from which gaseous potassium compounds were generated, a fixed bed holding the kaolin, and an on-line detector for the alkali metal concentration. The on-line alkali metal detector was based on ionization of alkali metals on hot surfaces and is capable of detecting alkali metals down to ppb levels. This makes it possible to perform experiments at alkali metal concentrations relevant to fluidized bed combustion of biomass fuels. In the experiments, KCl was used as the alkali metal source with inlet concentrations of 0.5–3.5 ppm. The experiments were performed at reactor temperatures of 800–900°C and a contact time of 0.26 s. The capture efficiencies of KCl were always above 97%. The capture efficiency was somewhat higher in oxidizing than in reducing gas atmospheres. In the oxidizing gas atmosphere, the conversion was slightly higher with H2O addition than without. The capture efficiency decreased slightly as temperature or KCl concentration was increased.
Fuel Flexibility and Petroleum Coke Combustion at Provence 250 MW CFB
Authors: Le Guevel Thierry , Thomas Philippe
Published: January 2009

The Provence 250 MWe CFB boiler was originally designed in 1992 for a local coal (Provence lignite) with a high sulfur and high ash content. This large CFB, features a pant leg bottom furnace, 4 cyclones and 4 fluid bed heat exchangers to provide the active temperature control of the furnace and reheated steam final temperature. After start up in 1995 with this local coal, several other fuel types were burnt. Mainly 3 fuels were tested over the last 5 years, on a long term basis, with various degrees of combination with the Gardanne coal up to full firing alone: • a lean coal (Gard, France), low volatile bituminous type, not far from semi anthracite type coals, • an imported coal, representative of low ash low sulfur content imported coal, • a petroleum coke, with a high sulfur content. This last test demonstrates the widest flexibility with regards to fuel reactivity range of a CFB plant with this architecture. The fuel, limestone and ash handling/injection systems were able to cope with this fuel diversity without equipment modifications. Since these tests were conclusive both on the pollutant emissions and on the operating concern, a permit to burn petroleum coke in commercial operation in a 250 MWe CFB boiler has been obtained in December 2001. This paper presents the main features and the results of the petroleum coke tests performed and compare them with the feedback on operating conditions of the boiler and emissions performances for Provence lignite and imported coal. These positive results demonstrate the wide fuel capability of large CFB boilers with this boiler architecture. First, they emphasize the critical role of advanced cyclones to accept fuels with very different reactivities and minimize limestone consumption. Second, these results show the role of the Fluid Bed Heat Exchangers system to control actively the furnace temperature, while controlling the reheated steam temperature without using spray.
Real-Time Simulation Model on Combustion System of 450 T/H Circulating Fluidized Bed Boiler
Authors: Hongwei Chen , Jianqiang Gao , Yonghua Li , Zhi Zhen
Published: January 2009

The paper introduced a real time simulation model of 450 t/h circulating fluidized bed boiler (CFBB) combustion system and its development method in detail. It is an important part model of operator training purpose simulator, which is for Baoding Thermal Power Plant, Hebei, China. The simulation model is created with the support of STAR-90™ Simulation software, and developed by way of engineering modular modeling (EMM) method. It is mainly composed by 4 model blocks, i.e. PRECMBST, FBC2, CYCLONE and JVLV, which stand for gas duct combustor under the bed, furnace combustor, cyclone gas separator, and loop seal valve in the CFBB respectively. The simulation results indicated that the model could properly reflect the dynamic and static characteristics of the combustion system of the CFBB. It not only can be used for training simulators, but also for system optimum design and control system analysis.
Design of a 2 x 160 MWel CFB Boiler Utilizing High Sulfur Turkish Lignite
Authors: Scheffknecht Guenter , Selc¸uk Nevin
Published: January 2009

Advantages of fluidized bed combustion technology such as the ability to burn wide variety of fuels efficiently and to control pollutant emissions without flue gas treatment systems have led to a steady increase in its commercial use over the past decades. There exist widely spread lignite reserves in Turkey with an estimated total quantity of 8 billion tons. A major proportion of this indigenous lignite is characterized by high sulfur, moisture and ash contents. CFBC is the fastest growing and still developing technology especially for such indigenous fuels. Meeting the environmental requirements needs high desulfurization efficiency. Special emphasis must therefore be given to the optimum use of the desulfurization agents, normally limestone, to achieve economical operation and to minimize solid by-product generation. This paper deals with a 2 × 160 MWel CFB plant, currently under construction in C¸an, Turkey. Indigenous lignite with a sulfur content of more than 8% (daf) will be utilized. In order to test the performance of Turkish lignites from C¸an mines, firing tests were performed at the 1.2 MW CFBC test rig at the Niederaussem power plant of RWE Rheinbraun in Germany. Main objective of the tests was to evaluate the sulfur retention efficiency to comply with Turkish emission limits.
Product Distribution From Flash Pyrolysis of Coal in a Fast Fluidized Bed
Authors: Cui Lijie , Yao Jianzhong , Lin Weigang , Zhang Zheng
Published: January 2009

The flash pyrolysis of Huolinhe coal was carried out in a fast-entrained bed reactor. The investigation focuses on the effects of pyrolysis temperature and particle size on pyrolysis product distributions and gas and liquid compositions. Increasing temperature results in an increase of the gaseous product. There is an optimum temperature on the maximum liquid yield, which is around 650°C. An increase in particle size leads to a decrease of liquid products. Some amount of phenol group was found in the liquid products, which may produce the chemicals with high value. The results provide fundamental data and optimal conditions to maximize light oils yields for the coal topping process.
Radial Hydrodynamics of High Velocity Gas-Solid Down-Flow Fluidized Beds
Authors: Li Songgeng , Lin Weigang , Yao Jianzhong
Published: January 2009

Experiments have been carried out in a gas-solids co-current down-flow circulating fluidized beds. The radial profiles of particle velocity and solid concentrations were measured by a fiber optical probe. Local solid flux was calculated based on the measured local particle velocity and solid concentration. The influence of gas velocity and solid recirculation rate on the radial flow structure has been examined. The experimental results show that the radial flow structure at high gas velocity has its own prominent characteristics in comparison with that at low gas velocity.