Column, air

An air pocket in the pump can cause low or no pressure or flow, erratic pressure, and changes in retention time data. It may be necessary to bleed air from the pump or prime the pump according to system startup procedures. Air pockets in the column will mean decreased contact with the stationary phase and thus shorter retention times and decreased resolution. Tailing and peak splitting on the chromatogram may also occur due to air in the column. Air bubbles in the detector flow cell are usually manifested on... 

An adsorption unit is to be designed to dry air using silica gel. A moving-bed design is considered in which silica gel moves down a cylindrical column in plug flow while air flows up the column. Air enters the unit at the rate of 0.129 kg of dry air/m2s and with a humidity of 0.00267 kg water/kg dry air. It leaves essentially bone dry. There is equilibrium between air and gel at the entrance to and the exit from the adsorption zone. Experiments were carried out to find the relative resistances of the external gas film and pellet diffusion. Referred to a driving force expressed as mass ratios then ... 

Near wood preserving facility, Bay of Quinte, Lake Ontario, 1978 Surface film Water column Air (ng/m )... 

Sample Loading. Prior to sample loading, the conditioned primary and secondary columns were connected in series by using column adapter connectors (J. T. Baker). The sorbents in each column were not allowed to dry out. A 10-mL aliquot of the 10-ppm aqueous standard mixture adjusted according to the treatment number of the design matrix (Table II) was loaded onto the column at a rate of 1.0-1.5 mL/min under an air pressure of 10 lb/in.2 applied at the top of the column. Air pressure was used instead of a vacuum to minimize losses of the more volatile components. 

Cooled reaction gases are absorbed in water/weak acid using a sieve tray-type tower. The bottoms from this tower is a so-called red product acid, the colour resulting from dissolved nitrogen oxide impurities. The red product acid is then bleached in a smaller sieve-tray stripping column. Air is bubbled through the red acid to strip out the dissolved nitrogen oxides. Bottoms from this column is the product nitric acid at 60%(wt.) concentration. 

Table 8.38 is the summary table of problem cost analysis. Please observe in Table 8.38 that each of the major equipment items are shown as a single entry, such as fractionation columns, air finfan coolers, and pumps. Next observe all of the line-item associated costs are also summed as single-item costs that include piping, concrete, steel, instruments, and electrical. Each of... 

Since helium and neon have boiling points considerably below that of nitrogen, these gases will collect on the nitrogen side of the condenser-reboiler associated with the double-column air separation system. Recovery of these gases is accomplished by periodic venting of a small portion of the gas from the dome of the condenser and transfer to a small condenser-rectifier refrigerated with... 

Description of the high-volume column air sampler (a) illustrates the assembled sampler and its shelter (b) shows the components of a typical high-volume air sampler. 

Gas-liquid systems of particular interest to the chemical engineer are encountered in bubble columns, spray columns, air lift, falling film, and stirred tank reactors. Usually the form of these reactors corresponds to that of vessels or columns. From the perspective of the chemical engineer, who is concerned with the conversion and selectivity of chemical transformations, it is of utmost importance that an intensive contact between a gas and a liquid be achieved and therefore very often one phase is continuous whereas the other is disperse. Therefore, the interfacial area and the size of the disperse phase elements constitute very important aspects of CFD modeling of these types of systems. 

The air-life fermentor consists of two concentric columns. The outer column has a conical bottom section with a perforated plate acting as a gas distributor. The inner column is positioned over this plate. Compressed air, enriched with CO2, is used to lift a suspension of mineral and bacterial culture in medium through this inner column. The suspension then falls to the reservoir and is air-lifted up the column again. The air-lift fermentor provides a good supply of oxygen and is able to keep high pulp densities (25%) of ore fully suspended in the medium. An illustrative example is provided by the work of Helle and Onken (47). Pachucas operate in a similar fashion to the air-lift fermentor, but there is no inner column. Air enters at the conical base of the reactor, aerates the medium, and suspends and circulates the mineral particles. Pachucas are useful reactors for building up culture stocks. 

Lang et al. reported the use of a post-column air-segmented reactor to enable fluorimetric detection of reserpine. As oxidizing reagent sulfuric acid - sodium nitrite was used, which converted reserpine into 3,4-dehydroreserpine. The reaction product was detected by measuring emission above 470 nm after excitation at a wavelength of 395 nm. 

The block of inter-linked columns offers robust simulation of a combination of complex distillation columns, as heat-integrated columns, air separation system, absorber/stripper devices, extractive distillation with solvent recycle, fractionator/quench tower, etc. Because sequential solution of inter-linked columns could arise convergence problems, a more robust solution is obtained by the simultaneous solution of the assembly of modelling equations of different columns. 

Air tritium Desiccant column Air tight container None... 

A stainless steel single-stage concurrent bubble column air lift loop reactor, 15 cm in dieuneter, with a bubbling layer, 275 cm high, and a stainless steel porous plate were used for the cultivation of Hansenula polymorpha (1) and Escherichia coli (2) (Fig. 1)... 

Perturbation theory can be extended to a two-group or multigroup model. This is necessary if the perturbation involves change in epithermal or fast neutron reaction rates (fuel element variation, for example). These problems are difficult and solutions are not described here. Some information is presented below on the effect of natural uranium columns, air columns and water columns. 

Fig. 3.1 Diagram of a two-column air separator with noble gas production. (1) Rectification column (pressure section) (2) Rectification column (low-pressure section) (3,5, 7) Combined condenser-evaporator unit ...

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