JOURNAL OF CHEMICAL ENGINEERING OF JAPAN Vol. 49(2016) No. 9

Owing to the shear flow of grease in pipes which is highly related to temperature and its rheological properties, the effect of thermorheological properties on shear flow of NLGI 3 lithium grease in pipes was investigated through theoretical and experimental methods. And the theoretical models for shear flow of grease in pipes, which contain flow velocity, shear rate and shear stress, were obtained by using the Herschel–Bulkley (H–B) rheology model. The H-B parameters on the flow curves were obtained by a rheometer. With the theoretical model and H–B parameters as foundation, the shear flow of grease in pipes was studied. Moreover, the variation mechanisms of shear flow were analyzed based on the results of field emission scanning electron microscopy (FESEM) and viscoelastic properties of grease. At last, grease delivering tests were carried out to verify those theoretical models. It was confirmed that the experimental data at different temperatures were remarkably consistent with the theoretical results.

Total gas holdups α_G in a cylindrical slurry bubble column were measured at various values of the superficial gas velocity J_G, the mean particle volumetric concentration C_S and the initial slurry height H₀ to investigate their effects on α_G. The column diameter D_H and height were 200 mm and 2000 mm, respectively. The gas, liquid and solid phases were air, water and hydrophilic silica particles of 100 µm in mean diameter, respectively. Experimental conditions were 0.025≤J_G≤0.40 m/s, 0≤C_S≤0.50 and 1.5≤H₀*≤ 5.0, where H₀*=H₀/D_H. The conclusions obtained are as follows: (1) α_G decreases with increasing H₀ and becomes independent of H₀ for H₀*>4 at low J_G, whereas it depends on H₀ at higher J_G even for H₀*>4, (2) the increase in C_S decreases α_G up to C_S ∼0.40, whereas α_G becomes independent of C_S at larger C_S, and (3) α_G in the slurry bubble column at various C_S, H₀ and J_G are well correlated in terms of the Froude number Fr_H using H₀ as a characteristic length.

A new CO₂ absorption fluidized bed reactor is presented for a continuous CO₂ capture process using sodium- or potassium-based solid sorbents. The absorption reactor includes a bubbling bed and a narrowed upper riser, which are connected by using a combination of a central tube and a draft tube. The control of solid circulation is demonstrated by a cold model. Effects on the solid circulation rate (G_s) of various parameters are investigated, including the geometry parameters (the position of the central tube exit, and the draft tube diameter), the operating parameters (gas velocity in the draft tube and the annular zone, the static bed material height, and the particle size). Finally, an expression is derived to correlate G_s as a function of the particle properties and operating conditions.

The discharge of heavy particles plays an important role in the practical application of air dense medium fluidized bed continuous separation. In order to solve the problems of scraper transport and discharge in the process, a special vibration fluidized bed separator was developed by taking advantage of negative-angle transport coupled to vibration energy. Experiments on negative-angle optimization were investigated by using the vibration fluidized bed separator, and on the basis of that, the effect of the projectile strength and air volume flow rate on the transport characteristics of the gas–solid fluidized bed was examined. A model for calculating the transport velocity of heavy particles in the vibration fluidized bed was established. The results show that, the transport characteristics improve when negative-angle is between −5.5° and −7.5°. Projectile strength, air volume flow rate and transport time are the main operating parameters, which all have an influence on the transport performance of the air dense medium fluidized bed. Transport velocity and efficiency increase and then level off with the increment of projectile strength and air volume flow rate. Taking account of the synergistic effects between separation and transport efficiency, such as the reliability and operation cost of vibration fluidized bed separator, the optimum operating parameters corresponding to the improved transport characteristics, are found with the projectile strength, air volume flow rate and transport time in the vicinity of 1.47, 140 m³/h and 40 s, respectively. The verification experiments show that the transport velocity by the calculation model is in good agreement with the experimental results.

A simplified electric field calculation is used to reveal several unique characteristics of the dielectrophoretic force to capture particles using electrodes on which conductive aligned micropillars are placed. This electrode configuration is a model to investigate a previous report about dielectrophoretic particle capture using an electrode on which carbon nanotubes have been synthesized. Conventionally, it has been believed that dielectrophoresis tends to capture larger particles because the dielectrophoretic force increases with increasing particle size when ordinal electrodes are used. However, when an electrode configuration with aligned conductive micropillars is used, small particles with diameters that are comparable to those of the micropillars can be selectively captured by dielectrophoresis. Accordingly, the size of the particles that need to be collected can be controlled by choosing an appropriate micropillar diameter. For relatively large particles, micropillars with a larger diameter can generate a stronger dielectrophoretic force over a larger area, such that a larger amount of particles can be collected. The number density of the micropillars was shown to negatively affect the dielectrophoretic force. The information obtained in this work will be useful for designing new DEP particle separators for size-selective particle capture. The use of controlled synthesis of CNTs is proposed to realize the fabrication of the electrode configuration modeled here.

Authors have been developing a spherical container having an inner wall constructed with skeletal ceramic units for transporting molten aluminum. This container is expected to provide innovative weight reduction and higher heat retaining property compared with current cylindrical containers having an inner wall made of castable refractory. In this study, a spherical inner wall with a combinative structure was designed: molten contacting part of the inner wall was constructed with skeletal unit made of reaction bonded silicon nitride (RBSN), while the non-contacting part with molten was constructed with skeletal unit made of aluminum titanate (AT). The quantity of heat emission from the container, temperature drop of molten in the container and thermal stress at the inner wall, while holding the molten, were simulated by heat transfer analysis. As a result, the spherical container reduced the quantity of heat emission compared with an inner wall constructed with only the RBSN unit, and was more reliable compared with that with only the AT unit. Thus, the new inner wall which enables a combination of light weight, high heat retaining property and reliability was proposed.

A novel fuzzy-logic based data treatment framework is proposed for the detection of outliers in process data. The proposed method incorporates outlier detection parameters into a fuzzy strategy. The method utilizes Hampel identifier for screening and fuzzy c-means cluster analysis for further evaluation. The Hampel identifier and fuzzy c-means clustering membership values are used as inputs. The outlierness of a data point is computed as a result of a 2-input/1-output fuzzy inference system. The overall fuzzy treatment framework is a generalized approach and can be modified to suit the application. The fuzzy treatment method was applied to benchmark penicillin production process data containing artificial data points with suspected outliers. The proposed method was able to detect the outliers in the process data with some irregularities. The results are presented along with a discussion on the advantages of this method as a flexible treatment of process data.

The present study examines the relationship between the cell growth rate and luminescence intensity by fabricating a system that enables the simultaneous measurement of the luminescence intensity and optical density of the liquid culture of Photobacterium kishitani, in order to investigate a possible mechanism for the luminescence oscillation. An instrument is fabricated using a microcomputer-controlled LED and a photo IC diode for the measurements. Two signals, cell density and bacterial bioluminescence were distinguished from one data set. A possible hypothesis for the oscillation in bacterial bioluminescence from oxygen level viewpoint has been created.

Natural chemicals, vanillin and syringaldehyde were successfully condensed with resorcinol affording two different calixarenes. The ability of these calixarenes obtained from vanillin (V-host) and syringaldehyde (S-host) as the hosts for heavy metal ions (Pb²⁺, Ni²⁺, Cd²⁺, and Cu²⁺) was investigated by fluorescence studies. The results show that the fluorescence of the calixarenes was effectively quenched by adding Pb²⁺, particularly for S-host. The result of Stern-Volmer analysis shows a nonlinear relationship with the Pb²⁺ concentration. The quenching was saturated in the Pb²⁺ range 0.20–1.0 M, indicating the multiassociation of Pb²⁺ with the host. The quenching constant (Ksv) was estimated from the linear region in the range 0.25–2 µM of Pb²⁺ to be 1.2×10⁶ M⁻¹ for the S-host and 0.22×10⁶ M⁻¹ for the V-host. Moreover, Benesi-Hildebrand analysis obtained the formation constant (K) to Pb²⁺ and the host, for 1.9×10⁵ M⁻¹ and 1.2×10⁶ M⁻¹ at the V- and S-host, respectively. These results indicate that Pb²⁺ was effectively included by the S-host.