A. Baldea

Institutul National de Cercetari Economice (INCE), Bucureşti, Hunedoara, Romania

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Publications (15)5.64 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The CO2 desorption from amine carbamate in non-aqueous solvents is of major importance for isotopic enrichment of 13C. A series of experiments were carried out in order to set up the conditions for the CO2 desorption. For this purpose, a laboratory- scale plant for 13C isotope separation by chemical exchange between CO2 and amine carbamate was designed and used. The decomposition of the carbamate solution was mostly produced in the desorber and completed in the boiler. Two different-length desorbers were used, at different temperatures and liquid flow rates of the amine-non-aqueous solvent solutions. The residual CO2 was determined by using volumetric and gaschromatographic methods. These results can be used for enrichment of 13C by chemical exchange between CO2 and amine carbamate in nonaqueous solvents.
    02/2012;
  • E. H. Dulf, C. Festila, A. Baldea
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    ABSTRACT: Based on the original cryogenic column conceived and built by National Institute for Research and Development of Isotopic and Molecular Technologies Cluj-Napoca, it is necessary to implement control algorithms for the industrial mode of operation of this equipment, in order to produce some chemical compounds with higher concentration in (13C), compounds asked in various domains. The present work deals with column efficiency analysis and stability in industrial mode of operation.
    01/2011;
  • Cl. Festila, E. H. Dulf, A. Baldea
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    ABSTRACT: The cryogenic 13C separation process is very slow, the concentration of this isotope reaches the desired value during weeks. A lot of variables, essential for the separation process must be controlled, so that any malfunction can compromise the whole production. The most important information about the system state is given by the carbon monoxide level sensor, with disastrous consequences by its failure (conductor breaking, power line failure, etc.). The authors try to solve this problem using an observer which generates the observed level information and compare, in normal mode of operation, the observed value with the real, measured variable. By sensor failure, the expected difference will increase drastically and the control system will switch to the observed level information.
    01/2010;
  • Cl. Festila, E. H. Dulf, A. Baldea
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    ABSTRACT: The process of the 13C in cryogenic separation column is an intricate one. A lot of parameters must be kept constant at empirical values. From among these, the nitrogen level and the temperature in condenser are essential for the separation process. In present, the liquid nitrogen level is controlled manually and any error of the operators can waste the final product. The paper proposes not only a system for liquid nitrogen level control, but also a second system able to decrease — due to the under-pressure — the evaporation temperature of liquid nitrogen in order to improve the separation process. The paper analyzes the two systems as independent entities and the interinfluences are treated as disturbances. The analysis in the true MIMO frame is a future task.
    International Conference on Automation, Quality and Testing, Robotics. 01/2010; 1:1-6.
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    ABSTRACT: The applications of stable isotopes from different chemical elements are well-known. Based on specific properties, a great diversity of isotope concentration (separation) methods have been developed, one of them being the cryogenic separation for (<sup>13</sup>C). After a short description of the separation equipment (separation column), the authors deal with the arising of the flooding process. Based on simplified equations, the evolution of an intended flooding is studied, divided in more stages: normal mode of operation, pre-flooding, ldquodischargerdquo period, flooding period and flooding damping. The next step of study will analyze the possibilities to avoid the flooding process.
    Automation, Quality and Testing, Robotics, 2008. AQTR 2008. IEEE International Conference on; 06/2008
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    ABSTRACT: The (<sup>13</sup>C) isotope separation process is a very important technical, scientific and industrial domain of activity. The operation plant is complex, with many input-output variables, difficult to model and to control. The authors identify the terminal and internal variable, define a dedicated structural model and conceive a complex control system, able to maintain the separation process at the desired parameters. Also, some descriptions about the dedicated transducers are given
    Automation, Quality and Testing, Robotics, 2006 IEEE International Conference on; 06/2006
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    ABSTRACT: The design and operational characteristics of a high repetition rate TEA CO2 laser are described. The laser operates at variable pulse repetition frequencies up to 100 Hz. Stable operation is obtained in a closed cycle which includes a gas mixture regenerator. Energies of up to 10 J/pulse are obtained in pulses having 25 MW peak powers. Average powers as high as 500 W are reached at the maximum pulse repetition frequency. The performance of optical components at various pulse repetition frequencies is presented.
    Journal of Physics E Scientific Instruments 11/2000; 21(4):393.
  • D. Axente, M. Abrudean, A. Baldea
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    ABSTRACT: The rate of nitrogen isotope exchange between NO and HNO3 has been measured as a function of nitric oxide pressure 0.1–0.4 MPa for 1 and 2 M·1–1 HNO3. It is concluded that15N/14N exchange rate in NO–HNO3 system has a linear dependence of NO pressure as indicated by rate measurements at different NO partial pressure and constant overall pressure, by adding helium in reactor. Using the rate law:R=k[HNO3]2[N2O3] the15N/14N exchange rates for nitric acid concentrations 1.5–10 M·1–1 were calculated.
    Journal of Radioanalytical and Nuclear Chemistry 01/1997; 222(1):149-152. · 1.41 Impact Factor
  • D. Axente, M. Abrudean, A. Bâldea
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    ABSTRACT: The rate of nitrogen isotope exchange between NO and HNO3 has been measured as a function of nitric acid concentration of 1.5–4M·1–1. The exchange rate law is shown to beR=k[HNO3]2[N2O3] and the measured activation energy isE=67.78kJ ·M–1 (16.2 kcal·M–1). It is concluded that N2O3 participates in15N/14N exchange between NO and HNO3 at nitric acid concentrations higher than 1.5M·1–1.
    Journal of Radioanalytical and Nuclear Chemistry 07/1996; 207(1):163-170. · 1.41 Impact Factor
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    ABSTRACT: Thermal decomposition of uranium double fluoride in a screw reactor in the temperature range of 250–500 °C is presented. Using integral reactor relation, kinetic parameters are discussed in terms of the shrinking core grain model. Arrhenius global activation energy is also determined.
    Journal of Radioanalytical and Nuclear Chemistry 01/1987; 111(2):423-428. · 1.41 Impact Factor
  • M. Abrudean, A. Bâldea, D. Axente
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    ABSTRACT: Nitrogen and hydrogen adsorption tests were performed in static and dynamic conditions, on clinoptilolite from Mřşid, district Sǎlaj, Romania, in natural and KCl ion exchanged form. Static adsorption capacities of hydrogen and nitrogen and adsorbed nitrogen quantity (dynamic capacity) in flow conditions were determined for several pressures. The separation of hydrogen (min. 98%) from hydrogen—nitrogen mixture using adsorption on clinoptilolite has been demonstrated.
    Zeolites 07/1985; 5(4):211–212.
  • D. Axente, M. Abrudean, A. Bâldea
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    ABSTRACT: Adsorption of carbon dioxide, sulphur dioxide, ammonia, and nitric oxide from air, and of hydrogen sulphide from methane, on Romanian natural zeolite in natural and modified form, is reported. The adsorption capacities, at 20°C, in flow conditions for several partial pressures of pollutants and for different linear velocity of the gaseous mixtures in the adsorption bed, were determined. The adsorption parameters of the studied zeolite indicates its suitability as a good adsorbant in air and methane purification plants.
    Zeolites 07/1983; 3(3):259-260.
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    ABSTRACT: The utilization of O labelled potassium phosphate KH2PO4, instead of radiophosphorus, P, labelled phosphate in biochemical and ecological studies concerning fertilizer phosphorus assimilation by plants is presented.The 30–60 mg dry plant samples were heated under 10 mm Hg vacuum in Pyrex ampoules to form carbon dioxide (COO) for O mass spectromietric analyses. Potassium phosphate labelled with 1.36 O atom per cent is sufficient to obtain a significant increase of the O plant content, the added O quantity in 0.5 kg soil being 1.4 × 10 g O in this case.
    Isotopes in Environmental and Health Studies - ISOT ENVIRON HEALTH STUD. 01/1979; 15(10):312-314.
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    ABSTRACT: The rate of the15N/14N isotopic exchange between NO−HNO3 at high nitric acid concentration (2–10M) have been measured. The experimental data were obtained by contacting nitric oxide at atmospheric pressure with nitric acid solution labelled with15N, in a glass contactor.
    Journal of Radioanalytical and Nuclear Chemistry - J RADIOANAL NUCL CHEM. 03/1976; 30(1):233-244.
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    ABSTRACT: The basic isotopic exchange reaction is responsible for the separation of15N in the Nitrox system that between gaseous nitrogen oxides and aqueous nitric acid with a single stage separation factor α=1.055 for 10M nitric acid, at 25°C and atmospheric pressure takes place. In order to know what happens in15N separation at higher pressure, when the isotopic transport between two phases is improved, a stainless steel laboratory experimental plant with a 1000 mm long × 18 mm i.d. column, packed with triangular wire springs 1.8×1.8×0.2 mm2, was utilised. At 1.5 atm (absolute), and 2.36 ml·cm−2·min−1 flow rate HETP was 7% smaller than at atmospheric pressure and 1.5 times smaller flow rate. HETP at 3.14 ml·cm−2·min−1 flow rate and 1.8 atm is practically equal with that obtained at atmospheric pressure and 2 times smaller flow rate. The operation of the15N separation plant at 1.8 atm (absolute), instead of atmospheric pressure, will permit doubling of the 10M nitric acid flow rate and of15N production of the given column.
    Journal of Radioanalytical and Nuclear Chemistry 240(3). · 1.41 Impact Factor