Transient Modelling of a Rotary-Kiln Pyrolyser

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Transient Modelling of a Rotary-Kiln Pyrolyser

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Validated ejector model for hybrid system applications

The aim of this work is the presentation of a new model for ejector performance calculation using a commercial tool. Due to the critical issues in recirculation performance, special attention is devoted to applications in hybrid systems based on high temperature fuel cells. The theoretical activity is supported by an experimental rig able to operate tests on ejectors at different operative conditions, with a layout similar to the fuel cell anodic recirculation. The model validation, operated considering experimental data obtained with this rig, is essential to evaluate the tool performance for design and off-design calculations. This aspect is particularly critical due to important limitations in the recirculation ratio (especially for the anodic side), to avoid unacceptable operative conditions in the fuel cells. The results presented in this work were obtained with this validated model for an ejector applied on the anodic side of a Solid Oxide Fuel Cell (SOFC). A parametric analysis was carried out to show the effects of several parameters on the recirculation performance. The fully independent analysis of the influence of different properties (carried out with a specifically validated model) is an important innovative result for the application of such ejectors on high temperature fuel cells

Solid oxide fuel cell hybrid system: A detailed review of an environmentally clean and efficient source of energy

This paper reports a review of an environmentally clean and efficient source of energy such as solid oxide fuel cell hybrid systems. Due to climate concerns, most nations are seeking alternative means of generating energy from a clean, efficient and environmental-friendly method. However, this has proven a big hurdle for both academic and industry researchers over many years. Currently, practical and technically feasible solution can be obtained via an integration of a microturbine and a fuel cell (hybrid systems). Combining the two distinct systems in a hybrid arrangement the efficiency of the microturbine increases from 25 to 30% to the 60-65% range. Hence, this paper outlines an engineering power generation solution towards the acute global population growth, the growing need, environmental concerns, intelligent use of energy with attendant environmental and hybrid system layouts concerning arising problems and tentative proposed solutions. Furthermore, advantages of a solid oxide fuel cell hybrid systems with respect to the other technologies are identified and discussed rationally. Special attention is devoted to modelling with software and emulator rigs and system prototypes. The paper also reviews the limitations and the benefits of these hybrid systems in relationship with energy, environment and sustainable development. Few potential applications, as long-term potential actions for sustainable development, and the future of such devices are further discussed

Surge prevention for gas turbines connected with large volume size: Experimental demonstration with a microturbine

The aim of this work is the demonstration of a surge prevention technique for advanced gas turbine cycles. There is significant surge risk in dynamic operation for turbines connected with large volume size additional components, such as a fuel cell stack, a saturator, a solar receiver or a heat exchanger for external combustion. In comparison with standard gas turbines, the volume size generates different behaviour during dynamic operations (with significant surge risk), especially considering that such additional components are including important dynamic constraints. In order to prevent the surge events, a vibration analysis was carried out to develop precursors which are able to highlight the approach of this unstable operative zone. Since the sub-synchronous content of the measured vibrations is significantly increasing approaching the surge line, special attention was devoted to this parameter. The demonstration of a surge prevention system based on the sub-synchronous vibration content was carried out at the Innovative Energy Systems Laboratory of the University of Genoa. In this laboratory, a recuperated microturbine connected with a large size vessel was used. Starting from the stable operation, closing a valve in the main air line or increasing the compressor inlet temperature produced operative conditions with significant surge risk. The increase in sub-synchronous vibration content detected by the control system was used to perform an active operation (bleed valve opening) to avoid the approaching surge event

Vibrational analysis for surge precursor definition in gas turbines

Compressor behaviour analysis in critical working conditions, such as incipient surge, represents a significant aspect in the turbomachinery research field. Turbines connected with large-size volumes present critical issues related to surge prevention especially during transient operations. Investigations based on acoustic and vibrational measurements appear to provide an interesting diagnostic and predictive solution by adopting suitable quantifiers calculated from microphone and accelerometer signals. For this scope a wide experimental activity has been conducted on a T100 microturbine connected with different volume sizes. A machine dynamical characterisation has been useful for better interpretation of signals during its transient to the surge. Hence, different possible methods of incipient surge identification have been developed through the use of different signal processing techniques in time, frequency and angle domain. These results will be useful for control system development to prevent compressor failures

Comprehensive Auditing in Nuclear Medicine Through the International Atomic Energy Agency Quality Management Audits in Nuclear Medicine Program. Part 2: Analysis of Results.

The International Atomic Energy Agency has developed a program, named Quality Management Audits in Nuclear Medicine (QUANUM), to help its Member States to check the status of their nuclear medicine practices and their adherence to international reference standards, covering all aspects of nuclear medicine, including quality assurance/quality control of instrumentation, radiopharmacy (further subdivided into levels 1, 2, and 3, according to complexity of work), radiation safety, clinical applications, as well as managerial aspects. The QUANUM program is based on both internal and external audits and, with specifically developed Excel spreadsheets, it helps assess the level of conformance (LoC) to those previously defined quality standards. According to their level of implementation, the level of conformance to requested standards; 0 (absent) up to 4 (full conformance). Items scored 0, 1, and 2 are considered non-conformance; items scored 3 and 4 are considered conformance. To assess results of the audit missions performed worldwide over the last 8 years, a retrospective analysis has been run on reports from a total of 42 audit missions in 39 centers, three of which had been re-audited. The analysis of all audit reports has shown an overall LoC of 73.9 ± 8.3% (mean ± standard deviation), ranging between 56.6% and 87.9%. The highest LoC has been found in the area of clinical services (83.7% for imaging and 87.9% for therapy), whereas the lowest levels have been found for Radiopharmacy Level 2 (56.6%); Computer Systems and Data Handling (66.6%); and Evaluation of the Quality Management System (67.6%). Prioritization of non-conformances produced a total of 1687 recommendations in the final audit report. Depending on the impact on safety and daily clinical activities, they were further classified as critical (requiring immediate action; n = 276; 16% of the total); major (requiring action in relatively short time, typically from 3 to 6 months; n = 604; 36%); whereas the remaining 807 (48%) were classified as minor, that is, to be addressed whenever possible. The greatest proportion of recommendations has been found in the category "Managerial, Organization and Documentation" (26%); "Staff Radiation Protection and Safety" (17.3%); "Radiopharmaceuticals Preparation, Dispensing and Handling" (15.8%); and "Quality Assurance/Quality Control" and "Management of Equipment and Software" (11.4%). The lowest level of recommendations belongs to the item "Human Resources" (4%). The QUANUM program proved applicable to a wide variety of institutions, from small practices to larger centers with PET/CT and cyclotrons. Clinical services rendered to patients showed a good compliance with international standards, whereas issues related to radiation protection of both staff and patients will require a higher degree of attention. This is a relevant feedback for the International Atomic Energy Agency with regard to the effective translation of safety recommendations into routine practice. Training on drafting and application of standard operating procedures should also be considered a priority

Planar Tc99m – sestamibi scintimammography should be considered cautiously in the axillary evaluation of breast cancer protocols: Results of an international multicenter trial

BACKGROUND: Lymph node status is the most important prognostic indicator in breast cancer in recently diagnosed primary lesion. As a part of an interregional protocol using scintimammography with Tc99m compounds, the value of planar Tc99m sestamibi scanning for axillary lymph node evaluation is presented. Since there is a wide range of reported values, a standardized protocol of planar imaging was performed. METHODS: One hundred and forty-nine female patients were included prospectively from different regions. Their mean age was 55.1 ± 11.9 years. Histological report was obtained from 2.987 excised lymph nodes from 150 axillas. An early planar chest image was obtained at 10 min in all patients and a delayed one in 95 patients, all images performed with 740–925 MBq dose of Tc99m sestamibi. Blind lecture of all axillary regions was interpreted by 2 independent observers considering any well defined focal area of increased uptake as an involved axilla. Diagnostic values, 95% confidence intervals [CI] and also likelihood ratios (LR) were calculated. RESULTS: Node histology demonstrated tumor involvement in 546 out of 2987 lymph nodes. Sestamibi was positive in 30 axillas (25 true-positive) and negative in 120 (only 55 true-negative). The sensitivity corresponded to 27.8% [CI = 18.9–38.2] and specificity to 91.7% [81.6–97.2]. The positive and negative LR were 3.33 and 0.79, respectively. There was no difference between early and delayed images. Sensitivity was higher in patients with palpable lesions. CONCLUSION: This work confirmed that non tomographic Tc99m sestamibi scintimammography had a very low detection rate for axillary lymph node involvement and it should not be applied for clinical assessment of breast cancer