Study of material agglomeration during nozzle injection of multiviscosity liquid into a fluidized bed reactor by the electric conductance method

Fluidized bed agglomeration is an important and challenging problem for thermal cracking in fluid cokers. A low coker temperature can be problematic because the bitumen is injected into the fluidized bed with a different viscosity, resulting in formation of agglomerates of varying sizes, which slows the cracking reactions. In the present study, the bed material agglomeration process during nozzle injection of multiviscosity liquid was investigated in a fluidized bed operated at different mass ratios of the atomization gas to the liquid jets (GLR = 1%–3.5%) and gas velocities (3.9U_mf and 5.9U_mf) based on a conductance method using a water–sand system to simulate the hot bitumen–coke system at room temperature. During the tests of liquid-jet dispersion throughout the bed, different agglomeration stages are observed at both gas velocities. The critical amount of tert-butanol in the liquid jets that could lead to severe agglomeration of the bed materials (poor fluidization) at GLR = 1% is about 10 wt% at the low fluidizing gas velocity (3.9U_mf) and 18 wt% at the high gas velocity (5.9U_mf). This study provides a new approach for on-line monitoring of bed agglomeration during liquid injection to guarantee perfect contact between the atomized liquid and the bed particles.     

The fast Fourier transform method and ill-conditioned matrices

We study the problem of finding numerical solutions of the linear algebraic equation, a*x=b, where a denotes an N × N ill-conditioned coefficient matrix. It is well-known that Gaussian elimination methods coupled with pivoting strategies are ineffective in this setting due to round-off error. We propose a new and simple application of the fast Fourier transform (FFT) method. Other viable methods, such as the QR method (QRM) or the singular value decomposition method (SVDM), have been proposed in the literature. The goal of this paper is to investigate the performance of the proposed method and compare it to other popular methods. The comparison is illustrated by computer simulation results using MATLAB.     

Characterization of Ultra Fine Solids（BS） in Athabasca Bitumen

The ultra fine (＜200 nm) inorganic solids (BS) were separated from bitumen which was washed by toluene and centrifugated at 2000 rpm. The result of PAS FTIR and image of TEM showed that the structure of BS particles was smiliar to that of kaolinite clay. On the surface of BS, both toluene insoluble organic matter and structural OH group are detected at the same time.The surface characteristics imparted a bi-wettable nature to the BS. As a result, the BS is able to stabilize fine water emulsion in the bitumen phase. The organic matter associated with BS is a possible factor of the fouling on catalyst and equipment.     

Quantum interference in carbon nanotubes

We present magnetotransport properties of a multiwalled carbon nanotube. We have developed a technique using electron beam lithography to connect a carbon nanotube with a small contact resistance. The temperature dependence of the nanotube is thermally activated down to 30 mK but with multiple energy gap. At low temperature, the magnetoconductance can be analysed in terms of quantum interferences. Both weak localisation and universal conductance fluctuations have been observed. The phase coherence length extracted from the weak localisation is consistent with the amplitude of the conductance fluctuations.     

Shell-model calculations of stellar weak interaction rates. I. Gamow-Teller distributions and spectra of nuclei in the mass range A = 45–65

Electron capture and beta-decay rates on nuclei in the mass range A = 45–65 play an important role in many astrophysical environments. The determination of these rates by large-scale shell-model calculations is desirable, but it requires to reproduce the Gamow-Teller strength distributions and spectra of the pf shell nuclei. We show in this paper that large-scale shell-model calculations, employing a slightly monopole-corrected version of the well-known KB3 interaction, fulfill these necessary requirements. In particular, our calculations reproduce the experimentally available GT₊ and GT₋ strength distributions and the nuclear halflives, and describe the nuclear spectra appropriately.     

Phase transitions in the three-state antiferromagnetic Potts model for different lattices

The ordered phases in the three-state antiferromagnetic Potts model for different lattices are investigated using the cluster-variation method in the pair approximation. There are two types of low-temperature ordered phases. The intermediate-temperature ordered phases are also analyzed.     

Event-by-event fluctuations and inclusive distributions

Event-by-event observables are compared with conventional inclusive measurements. We find that moments of event-by-event fluctuations are closely related to inclusive correlation functions. Implications for upcoming heavy ion experiments are discussed.     

Beta decay of 103In: Evidence for the Gamow-Teller resonance near 100Sn

The β decay of the neutron-deficient isotope ¹⁰³In was investigated by using total absorption γ-ray spectrometry on mass-separated sources. The measurement reveals a high-lying resonance of the β-decay strength in striking disagreement with high-resolution γ-ray data. The result is discussed in comparison with shell-model predictions.     

Vector meson radiation in relativistic heavy-ion collisions

The (σ, ω) model in the mean-field approximation where the meson fields are treated classically, describes much of observed nuclear structure and has been employed to describe the nuclear equation of state up to the quark-gluon phase transition. The acceleration of the meson sources, for example, in relativistic heavy-ion collisions, should result in bremsstrahlung-like radiation of the meson fields. The many mesons emitted serve to justify the use of classical meson fields. The slowing of the nuclei during the collision is modeled here as a smooth transition from initial to final velocity. Under ultra-relativistic conditions, vector radiation dominates. The angular distribution of energy flux shows a characteristic shape. It appears that if the vector meson field couples to the conserved baryon current, independent of the baryonic degrees of freedom, this mechanism will contribute to the radiation seen in relativistic heavy-ion collisions. The possible influence of the quark-gluon plasma is also considered.     

Vibrational spectra of β-lactams—III. potassium 2-azetidinone-1-sulfonate and its isotopic compounds

The IR and Raman spectra of potassium 2-azetidinone-1-sulfonate and its three deuterated and two ¹⁵N-substituted compounds have been recorded, and the observed bands have been assigned on the basis of the isotope effects and the normal coordinate analysis. Comparison of the force constants for the amide group among 2-azetidinone, 1-methyl-2-azetidinone and potassium 2-azetidinone-1-sulfonate indicates that there is a correlation between these constants and the ease of hydrolysis which was determined by NMR spectroscopy, depending on the amide resonance.