The beneficiation of three types of Slovakian coal, namely Cigel, Handlova, and Novaky coal was studied using triboelectrostatic separation. Three different types of triboelectrostatic separators -- parallel plate, cylindrical and louvered plate separators - were used for this study. It was found that the quality of separation was dependent upon the type of coal and the configuration of the separator utilized.

The beneficiation of three types of Slovakian coal was studied using triboelectrostatic separation. Three different types of separators-cylindrical, parallel, and louvered plate separators-were used for this: study. It is found that the quality of separation is dependent upon the type of coal and the configuration of the separator utilized.

V èlánku sú diskutované niektoré technické aspekty triboelektrostatickej separácie a výs-ledky aplikácie tohto postupu pri úprave troch typov uhlia, konkrétne energetického uhlia z Cíg¾a, Handlovej a Novák. Bolo zistené, že úèinnos separácie ve¾mi úzko závisí na druhu separovan uhlia. Prvé výsledky preukázali súvislos medzi úèinnosou separácie obsahom popola v uhlí.

An ultrasonic technique was developed to measure the slurry concentration in an autoclave reactor. Preliminary measurements were conducted on slurries consisting of molten FT-200 wax, glass beads, and nitrogen bubbles at a typical Fischer-Tropsch (FT) synthesis temperature of 265 degrees C. The data show that the velocity and attenuation of the sound are well-defined functions of the solid and gas concentrations in the molten FT-200 wax. The results suggest possibilities for directly measuring solids concentration during operation of a three-phase slurry reactor under the reaction temperature and with molten FT-200 wax. (C) 1997 Elsevier Science S.A.

Local gas holdup, bubble diameter and bubble rise velocity in the nitrogen/Drakeol-10 oil system were measured at both laboratory (ambient temperature and pressure) and industrially relevant (high temperature and pressure) conditions using a dual conductivity probe in a slurry-bubble-column reactor. It was found that a constant superficial velocity, the Sauter mean bubble diameter decreases with increasing pressure and temperature. The bubble rise velocity significantly decreases as the pressure increases. Large bubbles rise faster than smaller bubbles. Akita and Yoshida's correlation [1] was utilized to compute the bubble size. Predicted values agree with the experimental data at high temperature.

An indirect method of measuring gas holdup in-gas-liquid bubble column reactors has been developed. This technique is based on the analysis of the ultrasonic wave transmitted through the two-phase flow. Gas holdup measurements: have been made on water-nitrogen bubble system at ambient conditions. The data clearly show that the attenuation of the sound is a well-defined function of the gas holdup in the bubble column for homogeneous flow regime only (i.e., the superficial gas velocity is 4 cm/sec or less).

An ultrasonic technique was developed to measure the concentration of solids in an autoclave reactor. Preliminary measurements were conducted on slurries consisting of molten paraffin wax, glass beads, and nitrogen bubbles at 189 degrees C. The data show that the velocity and attenuation of the sound are well-defined functions of the solid and gas concentrations in the molten wax. The results suggest possibilities for directly measuring solids concentration during operation of a three-phase slurry reactor.

An ultrasonic technique is under development for measuring solids concentration in a three-phase slurry reactor. Preliminary measurements have been made on slurries consisting of water, glass beads, and air bubbles. The data show that both the sound speed and attenuation are well-defined functions of both the solid and gas concentrations in the slurries. A simple model is proposed to correlate the solids concentration with the measured ultrasonic signals.

An ultrasonic technique was developed to measure the concentration of solids in a three-phase slurry reactor. Preliminary measurements were taken on slurries consisting of water, glass beads, and nitrogen bubbles. The data show that the speed and attenuation of the sound are well defined functions of the solid and gas concentrations in the slurries. A simple model is proposed to correlate the concentration of solids with the measured characteristics of the ultrasonic signals.

Acetaldehyde (CH3CHO) is the major oxygenated product of the thermal reaction of carbon monoxide and chloromethane under reaction conditions, i.e., between 600-degrees-C and 700-degrees-C, and between 0.1 MPa and 1 MPa. The reaction conditions have a significant effect on the formation of the products.

The behavior of gas-solid-liquid flow in a slurry bubble column reactor was simulated using a well-posed hydrodynamic model. The three phases under study are nitrogen, 5-{mu}m iron oxide, and SASOL wax. The phases volume fractions at various axial and radial positions in the column were computed. Preliminary results of axial solid volume fractions are consistent with experimental observations and demonstrate the potential of this method for design of such reactors. The overall objective of this study is to develop experimentally verified hydrodynamic and Fisher-Tropsch reaction models for slurry bubble column reactors.

The application of the three-phase slurry reactor system to coal liquefaction processing and chemical industries has recently received considerable attention. To design and efficiently operate a three-phase slurry reactor, the degree of dispersion of the solid (catalyst) in the reactor should be understood. The solids distribution within the reactor greatly affects its performance. An ultrasonic technique is under development for measuring solids concentration in a three-phase slurry reactor. Preliminary measurements have been made on slurries consisting of molten paraffin wax, glass beads, and nitrogen bubbles at 189 C. The data show that the velocity and attenuation of the sound are well-defined functions of the solid and gas concentrations in the molten wax.

Acetaldehyde (CH3CHO) and acetic acid (CH3COOH) are major products of the thermal reaction of carbon monoxide and methyl chloride under certain reaction conditions.

A novel two-stage process capable of producing acetaldehyde from methane and syngas (CO and H2) has been studied. Methane, oxygen, and hydrogen chloride react over an oxyhydrochlorination catalyst in a first stage to produce chloromethane and water. In the second stage, chloromethane is added to a syngas mixture and catalytically converted to C1 to C44 hydrocarbons and acetaldehyde.

The effect of catalyst preparation methods on carbon monoxide hydrogenation selectivity over Na-Mn-Ni catalysts has been studied. The SiO2-supported Ni and Mn-Ni catalysts prepared from impregnation exhibited high methanation and hydrocarbon synthesis selectivity. The Mn-Ni catalysts prepared from coprecipitation of manganese and nickel nitrates with sodium carbonate showed high selectivity for C2+ oxygenate synthesis. Temperature-programmed desorption studies revealed that hydrogen chemisorption on the coprecipitated catalysts was highly activated. The results suggest that highly activated hydrogen chemisorption may lead to a hydrogen-deficient surface which would favor carbon monoxide insertion relative to hydrogenation.

The mechanism of synthesis gas conversion over cobalt-ZSM-5 catalysts to gasoline-range hydrocarbons has been examined. A correlation exists between the methane yield and the percentage aromatics in the liquid hydrocarbon product. This could be due to heat transfer effects or to the hydrogenolysis of propane and butane over cobalt, leading to the formation of additional methane. The formation of additional alkanes (propane and butane) is known to accompany the aromatization process. The percentage of methane made by the bifunctional catalyst 4.2% CoSiO2 + ZSM-5 was 1.7 times that made by the CoSiOm2 catalyst with a feed of H2CO = 1 at 280 °C, 21 atm, and WHSV = 0.77. An attempt was made to inhibit secondary hydrogenolysis reactions by the addition of copper to the cobalt catalyst. Under similar process conditions, this provided a very small help in keeping down the increase in percentage of methane upon the addition of ZSM-5. Addition of 5 and 10% propane to the synthesis gas showed no additional methane made by hydrogenolysis. If indeed some of the methane produced over cobalt-ZSM-5 catalysts is coming from hydrogenolysis of light alkanes, it is a small amount.

Synthesis gas was reacted over different compositions of iron-manganese Fischer-Tropsch catalysts in a slurry reactor. The reactor operates in a back-mixed mode with a continuous flow of feed gas through the catalyst suspended in the liquid medium. Four catalysts with iron-manganese ratios of 57/43, 44/56, 22/78, and 10/90 were investigated at identical process conditions after a standard activation procedure. With time on stream for each catalyst system, hydrogenation of olefins occurred, along with olefin isomerization reactions. Activity, selectivity, and stability are discussed in general. Analyses of used catalyst samples are also reported.