[en] Cyclone separator is one of the most widely used devices to separate and recover the industrial dusts from air or process gases. We developed Convex cyclone to reduce pressure losses. The body of Convex cyclones are designed with single continuous curve and convex shape as a substitute for cylinder-on-cone geometry. With a previous studies, experimental result shows that Convex cyclone are efficient for pressure loss reduction. However, there seems to be no clear explanation about collection efficiency. In this study, we perform additional experiments for a in-depth comprehension of Convex cyclone with particle counting collection efficiency measurement method. The experimental result shows that Convex cyclone can achieve maximum 40% pressure loss reduction with about 0.5 μm cut-size increasement. In addition, the experimental results indicated the existence of optimum convexity, minimum pressure loss, of cyclone wall

[en] The Colver Power Project in Cambria County, PA, looked good in nearly all aspects, but lenders had concerns about startup problems encountered by earlier waste coal circulating fluidized bed projects. Nevertheless, a closer look at the operating history of the earlier plants showed possible risks could be handled

[en] After the Fukushima Dai-ichi accident, the European Stress Tests Peer Review conclusions underlined the high priority for the implementation of hydrogen mitigation means in order to practically eliminate containment failure due to hydrogen combustion. For this purpose, the installation of passive autocatalytic recombiners (PARs) was recommended as the preferred option for future upgrading. Therefore, PARs have become a key element for hydrogen mitigation in many light water reactors worldwide. Recent international research programs have significantly supported the understanding of basic operational principles of PARs. In this context, the various OECD/NEA-THAI projects based on experiments in the THAI facility or the German national H2REKO projects performed in collaboration between RWTH Aachen University and Forschungszentrum Julich (FZJ) have to be mentioned. Experimental data from these projects enabled the improvement of existing numerical models as well as the development of advanced codes such as REKO-DIREKT and SPARK. However, present knowledge of PAR behavior under challenging severe accident boundary conditions is still based on early PAR qualification tests. For reliable simulation of PAR operation under severe accident conditions, more systematic investigations are required. To fill this gap of knowledge, recent investigations on the effect of carbon monoxide generated during molten core-concrete interaction (MCCI) and superposed flow conditions performed in collaboration of FZJ/RWTH, IRSN and ICARE represent first steps towards systematic parameter variations for a more profound understanding on the influence of both early and late phase phenomena. Further experimental programs have been performed to investigate PAR start-up under high humidity, cable fire products, and carbon monoxide. While superposed flow conditions showed only minor impact on the overall PAR performance, the presence of cable fire products - especially pyrolysis products - could significantly delay PAR start-up if the fire starts in the early accident phase, e.g. as initiating event. The presence of carbon monoxide, e.g. from MCCI, was found to cause catalyst poisoning and full loss of PAR operation under specific conditions. Further analysis of PAR operation in the late phase of an accident is foreseen as part of the SAMHYCO-NET project. The presentation provides a general overview of loads on PAR operation during a severe accident and describes the experimental programs and their analysis. Furthermore, the implication of the carbon monoxide poisoning effect on PWR accident analysis results will be presented. (author)

[en] Commercialization of fluidized bed combustion (FBC) technology could be enhanced by increased utilization of FBC products (ash). In the US, coal combustion products (CCP) are not hazardous under RCRA and are regulated as residual waste by the states. The composition of CCP from fluidized beds is primarily determined by the inorganic constituents in coal, the sorbent reaction products and the unreacted sorbent. The combustion system and the inclusion of other fuels may also affect the chemical composition, physical properties and leaching behavior. The alkalinity of the FBC material, residual lime and pozzolanic properties are desirable characteristics for use in soil stabilization and mine reclamation. At reclaimed surface coal mines, placement of CCP is intended to reduce the amount of acid mine drainage (AMD) produced at such sites. Neutralization, inhibition of acid forming bacteria, encapsulation of the pyrite or water diversion are believed to be the mechanisms facilitated by the alkaline material. Comparison of water quality, before and after injection of a grout composed of FBC ash and water indicated small increases in pH and decreases in acidity at discharge points. The concentrations of calcium and magnesium in water samples generally increased compared to background levels. The average concentration of trace elements (arsenic, cobalt, copper, nickel and zinc) was slightly elevated in the injection areas, but in down dip and discharge water samples were comparable to background levels. Over a four year period, the average acidity in the injected area decreased by approximately 30%, a value similar to another site where a mixture of class F fly ash and cement was injected. Although coal mine remediation is a beneficial environmental use of FBC products, its effectiveness may be related to the amount of FBCB used and the method of emplacement

[en] Thermoacoustic instability plays an important role in various technical applications, for instance in jet or rocket motors, thermoacoustic engines, pulse combustors and industrial burners. The main objective of this paper is to present the theory of thermoacoustic oscillations, and for this purpose a Rijke-type thermal device was built. The Rijke tube is a simple device open at both ends with a mean airflow and a concentrated heat source (a heated wire grid). It serves as a convenient prototypical example to understand thermoacoustic effects since it is a simplified thermoacoustic resonator; once excited, under certain conditions, it is capable of creating a sustained sound when thermal energy is added. In this paper we present a project that includes physical measuring, examination and modelling. We have employed electrically heated Rijke tubes in our thermoacoustic school project work, and present a numerical algorithm to predict the transition to instability; in this model the effects of the main system parameters are demonstrated. The aim of our project is to help our students enhance their knowledge about thermoacoustics and develop their applied information technology skills.

[en] Stimulus response method with radiotracers offers important information for process control in industry. Different approaches to data treatment (Convolution, Deconvolution, Laplace or Fourier transformation and modelling by differential equations) for process control in stationary or dynamic conditions are demonstrated in several examples from different branches of industry like waste water treatment, glass industry, control of combustion and chemical reactors. (author). 8 refs., 6 figs

[en] This volume contains the papers that were presented at the Fifth International Symposium on Gas-Solid Flows. The symposium included seven invited addresses that cover the major areas of interest within the field of gas-solid flows. The contributed papers cover a very broad range of topics, including analytical developments, full numerical simulation, numerical models, and experimental measurements. The main applications are to fluidized beds and pneumatic transport. Papers have been processed separately for inclusion on the data base

[en] Numerous containments of European light water reactors (LWR) are equipped with passive autocatalytic recombiners (PAR). PARs make use of the fact that hydrogen and oxygen react exothermally on catalytic surfaces generating steam and heat even below conventional concentration limits and ignition temperatures. These devices are designed for the removal of hydrogen generated during a severe accident in order to limit the impact of a possible hydrogen combustion. Alongside many experimental programmes performed at different institutions in the past which demonstrated the technical feasibility of this approach, investigations also revealed that there is still research needed in order to optimise and to enhance existing systems. The knowledge of the processes inside recombiners is still limited. The numerical code REKO-DIREKT has been developed in order to analyse the processes inside a PAR. The code calculates the local catalyst and gas temperatures and the concentration regression along the catalyst plates dependent on the inlet hydrogen concentration, the inlet gas temperature, and the flow rate. Numerous experiments have been performed in the REKO-3 facility taking into account different hydrogen concentrations, different flow rates, the presence of steam, the lack of oxygen, and different arrangements of the catalyst elements. The experimental results are used for the validation of the code providing also data specific for sub-models, e.g. the heat radiation model. The first basic calculations fit well with the experimental results indicating a proper understanding of the fundamental processes. The paper presents model calculations performed and the comparison with experimental results. (author)

[en] This paper deals with the policy aspects of energy conservation especially in the Federal Republic of Germany. The first part relates the achievements since the first world energy crisis. The second part underlines the policy aspects which have to be thought about, if the government wants to reduce the energy consumption more than the market place brings about. (TEC). 4 figs

[en] French gas-cooled reactors belonging to the Atomic Energy Commission (CEA), Electricite de France (EDF), Hifrensa (Spain), etc., commissioned between the 1950s and 1970s, have generated large quantities of graphite wastes, mainly in the form of spent fuel sleeves. Furthermore, some of these reactors scheduled for dismantling in the near future (such as the G2 and G3 reactors at Marcoule) have cores consisting of graphite blocks. Consequently, a fraction of the contaminated graphite, amounting to 6000 t in France for example, must be processed in the coming years. For this processing, incineration using a circulating fluidized bed combustor has been selected as a possible solution and validated. However, the first operation to be performed involves recovering this graphite waste, and particularly, first of all, the spent fuel sleeves that were stored in silos during the years of reactor operation. Subsequent to the final shutdown of the Spanish gas-cooled reactor unit, Vandellos 1, the operating utility Hifrensa awarded contracts to a Framatome Iberica SA/ENSA consortium for removing, sorting, and prepackaging of the waste stored in three silos on the Vandellos site, essentially graphite sleeves. On the other hand, a program to validate the Framatome fluidized bed incineration process was carried out using a prototype incinerator installed at Le Creusot, France. The validation program included 22 twelve-hour tests and one 120-hour test. Particular attention was paid to the safety aspects of this project. During the performance of the validation program, a preliminary safety assessment was carried out. An impact assessment was performed with the help of the French Institute for Protection and Nuclear Safety, taking into account the preliminary spectra supplied by the CEA and EDF, and the activities of the radionuclides susceptible of being released into the atmosphere during the incineration. (author). 4 refs, 11 figs, 1 tab