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Start-up Period (start-up + period)
Selected AbstractsTransient thermal modelling of heat recovery steam generators in combined cycle power plantsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2007Sepehr Sanaye Abstract Heat recovery steam generator (HRSG) is a major component of a combined cycle power plant (CCPP). This equipment is particularly subject to severe thermal stress especially during cold start-up period. Hence, it is important to predict the operational parameters of HRSGs such as temperature of steam, water, hot gas and tube metal of heating elements as well as pressure change in drums during transient and steady-state operation. These parameters may be used for estimating thermal and mechanical stresses which are important in HRSG design and operation. In this paper, the results of a developed thermal model for predicting the working conditions of HRSG elements during transient and steady-state operations are reported. The model is capable of analysing arbitrary number of pressure levels and any number of elements such as superheater, evaporator, economizer, deaerator, desuperheater, reheater, as well as duct burners. To assess the correct performance of the developed model two kinds of data verification were performed. In the first kind of data verification, the program output was compared with the measured data collected from a cold start-up of an HRSG at Tehran CCPP. The variations of gas, water/steam and metal temperatures at various sections of HRSG, and pressure in drums were among the studied parameters. Mean differences of about 3.8% for temperature and about 9.2% for pressure were observed in this data comparison. In the second kind of data verification, the steady-state numerical output of the model was checked with the output of the well-known commercial software. An average difference of about 1.5% was found between the two latter groups of data. Copyright © 2007 John Wiley & Sons, Ltd. [source] Effects of cationic polymer on start-up and granulation in upflow anaerobic sludge blanket reactorsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2004Ying Wang Abstract The upflow anaerobic sludge blanket (UASB) has been used successfully to treat a variety of industrial wastewaters. It offers a high degree of organics removal, low sludge production and low energy consumption, along with energy production in the form of biogas. However, two major drawbacks are its long start-up period and deficiency of active biogranules for proper functioning of the process. In this study, the influence of a coagulant polymer on start-up, sludge granulation and the associated reactor performance was evaluated in four laboratory-scale UASB reactors. A control reactor (R1) was operated without added polymer, while the other three reactors, designated R2, R3 and R4, were operated with polymer concentrations of 5 mg dm,3, 10 mg dm,3 and 20 mg dm,3, respectively. Adding the polymer at a concentration of 20 mg dm,3 markedly reduced the start-up time. The time required to reach stable treatment at an organic loading rate (OLR) of 4.8 g COD dm,3 d,1 was reduced by more than 36% (R4) as compared with both R1 and R3, and by 46% as compared with R2. R4 was able to handle an OLR of 16 g COD dm,3 d,1 after 93 days of operation, while R1, R2 and R3 achieved the same loading rate only after 116, 116 and 109 days respectively. Compared with the control reactor, the start-up time of R4 was shortened by about 20% at this OLR. Granule characterization indicated that the granules developed in R4 with 20 mg dm,3 polymer exhibited the best settleability and methanogenic activity at all OLRs. The organic loading capacities of the reactors were also increased by the addition of polymer. The maximum organic loading of the control reactor (R1) without added polymer was 19.2 g COD dm,3 d,1, while the three polymer-assisted reactors attained a marked increase in organic loading of 25.6 g COD dm,3 d,1. Adding the cationic polymer could result in shortening of start-up time and enhancement of granulation, which may in turn lead to improvement in the efficiency of organics removal and loading capacity of the UASB system. Copyright © 2004 Society of Chemical Industry [source] Projected impact of colorectal cancer screening with computerized tomographic colonography on current radiological capacity in EuropeALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 4 2008C. HASSAN Summary Background, The impact of a primary colorectal cancer screening with computerized tomographic colonography on current radiological capacity is unknown. The multispecialty needs for computerized tomographic examinations raise some doubts on the feasibility of a mass colorectal cancer screening with computerized tomographic colonography. Aim, To assess whether the number of available computerized tomographic units in Europe is adequate to cover population screening with computerized tomographic colonography. Methods, A mathematical and a Markov model were, respectively, used to assess the number of computerized tomographic colonography procedures needed to be performed each day in the start-up and in the steady-state phases of a colorectal cancer screening programme in Europe. Such outcome was divided for the total number of computerized tomographic machines aged <10 years estimated to be present in the European hospitals. Results, At a simulated 30% compliance, 28 760 130 European people would need to be screened by the 3482 available computerized tomographic units in a 5-year start-up period, corresponding to 6.6 CTC/CT unit/day. Assuming a 10-year repetition of computerized tomographic colonography between 50 and 80 years, the number of computerized tomographic colonography needed to be performed in the steady-state period appeared to be 4.3/CT unit/day. Conclusions, The current radiological capacity may cover the need for a primary colorectal cancer screening with computerized tomographic colonography in a steady state. On the other hand, a substantial implementation of the current computerized tomographic capacity or a synergistic approach with other techniques seems to be necessary for the start-up period. [source] A Preliminary Report of Knowledge Translation: Lessons From Taking Screening and Brief Intervention Techniques From the Research Setting Into Regional Systems of CareACADEMIC EMERGENCY MEDICINE, Issue 11 2009Edward Bernstein MD Abstract This article describes a limited statewide dissemination of an evidence-based technology, screening, brief intervention, and referral to treatment (SBIRT), and evaluation of the effects on emergency department (ED) systems of care, utilizing the knowledge translation framework of reach, effectiveness, adoption, implementation, and maintenance (RE-AIM), using both quantitative and qualitative data sources. Screening and brief intervention (SBI) can detect high-risk and dependent alcohol and drug use in the medical setting, provide early intervention, facilitate access to specialty treatment when appropriate, and improve quality of care. Several meta-analyses demonstrate its effectiveness in primary care, and the federal government has developed a well-funded campaign to promote physician training and adoption of SBI. In the busy environment of the ED, with its competing priorities, researchers have tested a collaborative approach that relies on peer educators, with substance abuse treatment experience and broad community contact, as physician extenders. The ED-SBIRT model of care reflects clinician staff time constraints and resource limitations and is designed for the high rates of prevalence and increased acuity typical of ED patients. This report tracks services provided during dissemination of the ED-SBIRT extender model to seven EDs across a northeastern state, in urban, suburban, and rural community settings. Twelve health promotion advocates (HPAs) were hired, trained, and integrated into seven ED teams. Over an 18-month start-up period, HPAs screened 15,383 patients; of those, 4,899 were positive for high risk or dependent drinking and/or drug use. Among the positive screens, 4,035 (82%) received a brief intervention, and 57% of all positives were referred to the substance abuse treatment system and other community resources. Standardized, confidential interviews were conducted by two interviewers external to the program with 24 informants, including HPAs and their supervisors, clinicians, nurse managers, and ED directors across five sites. A detailed semistructured format was followed, and results were coded for thematic material. Barriers, challenges, and successes are described in the respondents' own words to convey their experience of this demonstration of SBIRT knowledge translation. Five of seven sites were sustained through the second year of the program, despite cutbacks in state funding. The dissemination process provided a number of important lessons for a large rollout. Successful implementation of the ED-SBIRT HPA model depends on 1) external funding for start-up; 2) local ED staff acting as champions to support the HPA role, resolve territorial issues, and promote a cultural shift in the ED treatment of drug and alcohol misuse from "treat and street" to prevention, based on a knowledge of the science of addiction; 3) sustainability planning from the beginning involving administrators, the billing and information technology departments, medical records coders, community service providers, and government agencies; and 4) creation and maintenance of a robust referral network to facilitate patient acceptance and access to substance abuse services. [source] Developments in EU biofuels policy related to sustainability issues: overview and outlookBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 4 2007Marc Londo Abstract In the current debate on present and future biofuels policy, sustainability issues play an important role. In this perspective, we discuss a number of factors in the framing of the biofuels sustainability debate, and describe their role over the last 25 years or so in which biofuels have been on the political agenda. Our first conclusion is that biofuels policy is related to several underlying objectives, such as climate change, security of supply and other drivers. Therefore, the policy will structurally need to be monitored in its impacts, in order to keep these impacts in concordance with these objectives. In the long term, biofuels policy might be substituted by instruments that more directly relate to the objectives. Second, current sustainability issues concerning biofuels relate to either the production chain or to the regional system in which biofuels compete for land. Finding suitable indicators and setting up monitoring schemes are key challenges. Furthermore, a safeguarding scheme needs to meet two conflicting requirements: on the one hand it is important to implement it over many regions and many sectors (including non-energy), but on the other hand the problem requires implementation in the short term. Starting with monitoring only may cause an issue of legitimacy. Finally, we propose some elements for a robust development strategy. This includes pushing forward with a sustainability safeguarding scheme, within the given constraints. During the start-up period of such schemes, non-certified biofuels and feedstock might be discouraged, simultaneously stimulating production initiatives operating under certification. © 2007 Society of Chemical Industry and John Wiley & Sons, Ltd [source] | |||||||||||||