Investigation of the impact of steady-state VVER-1000 (1200) core characteristics on the reactor stability with respect to xenon oscillations

The article presents a method for obtaining an analytical expression for the criterion of stability of a VVER-1000 (1200) reactor with respect to xenon oscillations of the local power in the core, containing an explicit dependence of the criterion ratio coefficients on the arbitrary axial neutron field distribution in steady states of the core. Based on the data of numerical experiments using a full-scale model of the Kalinin NPP power units, the authors present the results of checking the validity of this expression for the reactor stability criterion with respect to xenon oscillations for different NPPs with VVER-1000 (1200) reactors.

Micro-Reactor System for Complete Oxidation of Volatile Organic Compounds

Based on previous Computational Fluid Dynamics (CFD) design results, an 11 channel microreactor of dimensions (0.5 mm × 0.5 mm × 100 mm) (width × depth × length) and optimal manifold geometry was fabricated, coated with a newly-developed Au/SBA-15 catalyst and then integrated in an experimental rig specifically built for this research. Propane (as model volatile organic compound) oxidation experiments were conducted at three different flow velocities, 12.5, 15.4 and 17.5 m/min, respectively, at six temperatures, 150, 200, 225, 250, 275, and 300 °C, respectively. The catalyst was prepared by one-pot sol-gel synthesis of SBA-15 with MPTMS (3-mercaptopropyl-trimethoxy-silane) before loading with HAuCl4 gold precursor and then characterized by SEM/EDX, TEM and wide angle XRD. A novel catalyst coating technique was developed, using airbrush (0.3 nozzle) to spray a catalyst slurry into the microchannels that produced a thin, firm and uniform layer of Au/SBA-15 catalyst coating inside the microreactor. The experimental measurements revealed that propane conversion increased as the flow feed rates decreased and increased with increasing temperatures in the reactor. For the built microreactor and for the flows and temperatures set, the combustion of propane was possible with measurable conversions and reasonable reactor stability, the performance of the catalyst appeared to be central to the satisfactory operation of the reactor.

Pengaruh Laju Pengadukan Terhadap Stabilitas Digester Anaerobik Satu Tahap pada Pembentukan Biogas dari Limbah Cair Pabrik Kelapa Sawit Menggunakan Lab Scale Reaktor Batch

Mixing is essential to increase the efficiency of interactions between active microbes and organic matter during the anaerobic digestion process. The purpose of this research is to study the effect of mixing rate on the stability of one stage anaerobic digesters in biogas production in terms of pH and alkalinity. The production of biogas from palm oil mill effluent was carried out in a 6000 ml batch reactor at varying mixing rates: 100 rpm, 150 rpm, 200 rpm, 250 rpm, and 300 rpm. The reactor is operated with a mixture condition maintained at a pH of 7 ± 0.2 and an operating temperature of 55 ° C. NaHCO3 is added to the mixture to control and maintain the pH of the mixture. Analysis of pH and alkalinity is carried out every day to see the reactor stability. The best results were obtained at a mixing rate of 200 rpm with the pH produced stable during the process is 7. The alkalinity profile produced at each mixing rate was relatively stable with an alkalinity range is 3500-4500 mg/L. The best mixing rate is 200 rpm with a stable pH and alkalinity and the highest biogas production is 457 ml/day.