Showing papers on "Packed bed published in 1976"

Packed Bed Thermal Storage Models for Solar Air Heating and Cooling Systems

Abstract: In order to simulate solar heating systems where air is the transfer fluid, an adequate model of the packed gravel bed energy store is required. One model of a packed bed thermal store can be obtained by solving the partial differential equations of the Schumann Model as described by Jakob (1957). However, when these equations are solved as part of a long term simulation, the computing costs become unacceptably high. This paper describes the development of a simple model, whose validity is demonstrated by comparing the long term behavior of a system incorporating both the complex and simplified packed bed models. (WDM)

Application of the limiting current method to mass transfer in packed beds at very low reynolds numbers

Abstract: The limiting current technique is used to obtain mass transfer coefficients at very low Reynolds numbers (Re less than 0.1) in a packed bed consisting of stainless steel spheres. The data show that for Re less than 0.015, the Nusselt numbers are below those predicted by existing empirical correlations. The results are discussed in the light of some mathematical models for packed beds reported in the literature and show semiquantitative agreement with the values predicted by Sorensen and Stewart (1974a).

Process for the exchange of hydrogen isotopes using a catalyst packed bed assembly

Abstract: A process for the exchange of hydrogen isotopes between streams of gaseous hydrogen and liquid water is described, wherein the streams of liquid water and gaseous hydrogen are simultaneously brought into contact with one another and a catalyst packed bed assembly while at a temperature in the range 273° to 573° K. The catalyst packed bed assembly may be composed of discrete carrier bodies of e.g. ceramics, metals, fibrous materials or synthetic plastics with catalytically active metal crystallites selected from Group VIII of the Periodic Table, partially enclosed in and bonded to the carrier bodies by a water repellent, water vapor and hydrogen gas permeable, porous, polymeric material, and discrete packing bodies having an exterior surface which is substantially hydrophilic and relatively non-catalytically active with regard to hydrogen isotope exchange between hydrogen gas and water vapor to that of the catalyst bodies. The catalytically active metal crystallites catalyze the hydrogen isotope exchange reaction between hydrogen gas and water vapor in the presence of liquid water while the polymeric material retards the loss of activity of the catalytically active metal crystallites caused by contact thereof by the liquid water. This catalyzed chemical isotope exchange proceeds simultaneously with isotope exchange from water vapor to liquid water by a non-catalyzed, physical evaporation and condensation exchange reaction and the addition of the discrete hydrophilic packing serves to increase this rate of isotope exchange between the water vapor and the liquid water. In other embodiments the catalyst structure and hydrophilic packing structure comprise a mixture of corrugated and flat metal sheet or gauze or a mixture of corrugated metal sheets or gauze packed or rolled such that fluid flow passage interstices are provided between the sheets and with the catalytically active metal crystallites deposited on some of the metal sheets or gauze.

A heat transfer study on packed bed reactors of immobilized glucoamylase

Abstract: Enzymes are generally sensitive to temperature changes. Porous glass particles used for glucoamylase immobilization are poor thermal conductors and a non-uniform temperature distribution can conceivably develop in a packed bed reactor of immobilized glucoamylase on porous beads. This study was made to determine experimentally the temperature and concentration profiles in an immobilized glucoamylase column. This work provides a procedure for examining possible heat effects on reactor column performance in enzyme applications.

Method and apparatus for carrying out hydrogenation reactions

Abstract: This invention comprises a method of achieving a highly efficient use of catalyst in conducting hydrogenation reactions of hydrocarbons in the liquid state by means of solid catalysts. The catalyst is wholly contained in a microporous layer no thicker than 200 microns deposited on the outside surface of otherwise inert support particles. The catalyst particles, of the order of 10 mm diameter, are contained in a fixed, vertical, packed bed, and are brought into contact with the liquid hydrocarbon and hydrogen by passing the two fluids in cocurrent flow, either upwards or downwards, through the bed at substantially greater gas velocities than are usually employed in fixed bed catalytic reactors used for hydrogenating hydrocarbons in the liquid state. The effect of the high gas velocity is to achieve substantially higher heat and mass transfer rates among the three phases (catalyst, liquid hydrocarbon, and gaseous hydrogen) than are achievable under conventional conditions of operation of fixed bed catalytic reactors used for hydrogenating hydrocarbons in the liquid state. The combined effects of the high gas velocity and the mode of deposition of the catalytically active components on the catalyst support, are the achievement of a large global reaction rate in the reactor, combined with a high internal effectiveness factor for the catalyst. For fast hydrogenation reactions, for which the invention is most advantageously employed, a comparable efficiency of catalyst utilization can at present be achieved only by using catalyst in the form of powder or granules so small as to preclude their use in a fixed bed reactor.

Liquid-phase mass transfer coefficient and gas holdup in a packed-bed cocurrent up-flow column.

Abstract: Packed-bed cocurrent up-flow reactors gave better results than conventional trickling flow reactors in hydrodesulfurization of heavy oil. To find the characteristics of this up-flow type reactor, liquid-phase mass transfer coefficient, gas-liquid interfacial area and gas holdup in a column packed with 0.1, 0.28 or 0.43 cm glass beads were studied using the oxidation reaction of sodium sulfite. Experiments were carried out at a reaction temperature of 20°C. Superficial liquid and gas velocities based on empty column, ul and ug, were 1-6 and 0.5-6cm/sec, respectively, for any size of glass beads. With the values of ul and ug, glass beads bed remained stationary, expanded or fluidized. Stagnant gas holdup was observed under the condition of ul

Process for fluidized contact

Abstract: A fluid consisting of either a liquid or a mixture of a liquid and a gas is intimately contacted with solid particles by introducing the fluid into a contacting vessel to form a fluidized layer of the solid particles. A bed of porous packing is also placed in the contacting vessel and the upper end of the fluidized layer of solid particles is located within the porous packed bed.

Residue thermal cracking process in a packed bed reactor

Abstract: A thermal cracking process comprising thermally cracking a non-deasphalted residual oil in a thermal cracking zone containing a fixed bed of inert solids.

Mass or heat transfer or separation of solid or immiscible components from fluids

Abstract: A packed column comprising a bed of bodies of fibrous material for the interphase transfer of mass and/or heat and the separation of solids or immiscible phases from fluids. Each body is of generally cylindrical form and includes a centrally disposed axial support from which a large number of fibers extend radially, the fibers being secured to the support. The bodies are disposed in the bed at random and interlocked with each other. The density of the fibers in count per unit volume varies from point to point in the packing body and in the bed. The volume of each body is small compared to the volume of the bed. In mass and/or heat transfer with this bed a liquid is distributed over the top of the bed and trickles downwardly through the packing in a multitude of irregular paths while the gas is projected upwardly through the bed. The gas contacts the liquid over a very large surface area for an extended time interval and effective mass and/or heat transfer between the gas and liquid takes place. In the separation of solids or an immiscible phase from a fluid, the fluid is transmitted once or repeatedly through the bed and the fibrous packing acts to agglomerate or coalesce the solid or immiscible phase components and deposit these components on the fibrous surface.

Method for the removal of the dusts from combustion exhaust gases

Abstract: A method for the removal of the dusts from combustion exhaust gases, particularly those of heavy oils, by using a fixed packed bed without a remarkable increase in the pressure loss at the fixed packed bed, which is characterized in that the filler filled in the fixed packed bed is a spherical, cylindrical or annular filler containing pores having a pore diameter which ranges from 100 to 70,000 A and a pore volume of not less than 0.1 cm3 /g, at least 20% of the pores have a pore diameter of not less than 1,000 A, and the filler having a diameter of 1 to 15mm at a minimum.

Controlling method for pseudomoving bed

Abstract: PURPOSE: To find simply the concn. distribution in a packed bed so as to operate a pseudomoving bed always under the most suitable condition, e.g., in the separation of fruit sugar from aq. soln. of isomerized sugar using a pseudomoving bed by measuring the concn. of a fluid circulating through the pseudomoving bed at a point. COPYRIGHT: (C)1978,JPO&Japio

Method for opening a high-density packed column in liquid chromatography

Abstract: Method for opening a high-density packed column in liquid chromatography wherein a large number of components in a solution are separated by means of a column in which a swollen gel is packed at a high density The improvement involves passing air through the column while heating the column to a temperature above at least 40° C to shrink the volume of the packed column, and then opening the column According to this process, there is no loss in the expensive gel nor contamination thereof and yet it's operating efficiency is greatly improved