Bench-scale column

The results of the breakthrough studies indicated that the optimum flow rate would be approximately 50-100 bed volumes/h. These results were used to scale-up the bench-scale columns for pilot plant studies. 

Scale-up from a Pilot- or Bench-Scale Column This is a very common scale-up. No reduction in efficiency on scale-up is expected as long as several precautions are observed. These precautions, generally relevant to pilot- or bench-scale columns, are spelled out with specific reference to the Oldershaw column. 

Scale-up from a Pilot or Bench-Scale Column. 14-51... 

A rapid small-scale column test protocol for bench-scale evaluation of alumina adsorbents was recently developed at the University of Houston (7). The RSSCT allows for faster evaluation of arsenic adsorbents using bench-scale column tests with actual or synthetic groundwaters. The RSSCT protocol uses low-pressure (<5 psig) glass minicolumns containing 4.0 mL of 60 X 100 mesh adsorbent. Compared with the standard (28 X 48 mesh) adsorbents currently used in pilot-scale and minicolumn tests, the RSSCT allows the use of faster flow rates so that the column runs can be completed in one-fourth to one-tenth the time required for the standard tests. 

An example of a size-exclusion chromatogram is given in Figure 7 for both a bench-scale (23.5 mL column) separation and a large-scale (86,000 mL column) mn. The stationary phase is Sepharose CL-6B, a cross-linked agarose with a nominal molecular weight range of 5000-2 x 10 (see Fig. 6) (31). 

Portable scales generally have a platform near the floor with the indicator mounted on a column for ease of operation. These scales may be on wheels, and many are battery-powered. Capacities are generally less than 600 kg. Bench scales can be placed on a wheeled table for similar use. 

Isolation procedures for many biochemicals are based on chromatography. Practically any substance can be selected from a crude mixture and eluted at relatively high purity from a chromatographic column with the right combination of adsorbent, conditions, and eluant. For bench scale or for a small pilot plant, such chromatography has rendered alternate procedures such as electrophoresis nearly obsolete. Unfortunately, as size increases, dispersion in the column ruins resolution. To produce small amounts or up to tens of kilograms per year, chromatography is an excellent choice. When the scale-up problem is solved, these procedures should displace some of the conventional steps in the chemical process industries. 

Two types of bench-scale studies are common a flask (respirometer) study and a column study. For flask studies, samples of the aquifer matrix and contaminated... 

The recovery of products from biotechnological processes has traditionally been focused on bench-scale separation approaches, such as electrophoresis or column liquid chromatography. These methods are dilScult to scale up to production levels and often become prohibitively expensive for medium-and low-value products. 

In a typical bench-scale study, five columns were set up under the strict quality control-quality assurance (QA-QC) requirements of this project one column for the control of reagents and glassware, one column for the control of the resin blank, and triplicate columns for model compound studies. 

Because the volume of the resin required has been established (to handle 103 bed volumes/h), the inside diameter (D) and the length (L) of the bed can be determined in order to be comparable to the residence time of the quinaldic breakthrough study. Two approaches can be followed in length and diameter determinations. One involves duplicating the breakthrough or the bench-scale studies. The second approach involves the practical aspects such as L/D and the pressure drop phenomenon. As a general rule, L/D should be more than or equal to 10. Therefore, a 16-in. X 1.0-in. i.d. column was constructed with the following characteristics surface area = 4.9 cm2 residence time = 0.57 min bed volume/h = 103 flow rate = 347 mL/min linear velocity = 70.8 cm/min L/D = 16. 

Bench-scale tests were conducted to determine design parameters and operability of Che distillation process for the pilot plant. The column, reboller, and condenser used in the bench-scale system were constructed of fiberglass-reinforced ethylene-chlorotrifluoroethylene. The heat exchangers were spaghetti tube bundles constructed of fluorinated ethylene-propylene copolymer. 

To provide the basic information necessary to fulfill the above requirement and design a 15,000-gallon-per-day pilot plant, a freezer and wash column with a capacity of 300 gallons per day were built and tested for more than a year. Extensive bench-scale tests were made previous to this. The results reported in Table IV were taken on the 300-gallon-per-day unit and are typical of those used to design the 15,000-gallon-per-day unit. 

Fig. 5. Bench-scale production of pyrroles from ketoximes and acetylene (84M11) 1, reactor 2, extractor 3, stripper 4, extragent collector 5, extragent trap 6, vacuum pump 7, extragent trap 8, explosive valve 9, rotameter 10, refluxer column 11, cooler.

Experimental verification of the separation of the mixture u-hexane-ethyl acetate by heteroazeotropic batch distillation in a bench scale rectification column... 

Traditional methods of pharmaceutical analysis involve a series of multiple steps. For example, the identification of natural products traditionally involves the scale-up of fermentation broths, solvent extraction, liquid/liquid or column fractionation, chromatographic fraction collection, and spectroscopic analysis (usually NMR) of the individual components. Figure 5.2 illustrates the integration of these bench-scale steps into a dedicated LC/MS/MS system (Lee et al., 1997). Integration provides unique and powerful advantages for the on-line identification of natural products (Kerns et al., 1994 Ackermann et al., 1996a). Experiments that once required 2 weeks to perform with traditional approaches are now performed in half a... 

Thermostatting of the columns was accomplised at 62°C with a small oil filled bath (model PY1, Bench Scale Equipment Co.). 

Bubble regime (Fig. 6.26s) or deep pool 1 occurs at low vapor velocities, Discrete noncoalescing bubble swarms rise through quiescent liquid, which has a very clear surface. For the air-water system, Wallis (100> showed that this regime is unlikely to occur when vapor velocities exceed 0.15 ft/sec, and therefore, in industrial columns. It may occur in bench-scale and pilot columns where outlet weirs are tall. If this regime occurs in a test unit, caution is required in data scale-up. 

Cellular foam occurs at low vapor velocities in small columns, where the wall provides foam stabilization. It occurs with some systems or tray designs but not with others and is promoted by surface tension effects such as the Marangoni effect (99). Cellular foam is uncommon in industrial columns. The foam that causes problems in industrial installations is mobile foam, where the bubbles are in turbulent motion. Mobile foam is associated with the froth and emulsion regimes. Cellular foam is encountered in bench-scale and pilot-scale columns. If cellular foam occurs in the test unit, caution is required when scaling up the results. 

In this pi-space, measurements were evaluated which were performed in a bench-scale flotation cell (Fig. 3 a) of D = 0.6 m. The flotation cell input consisted of biologically purified waste water, containing = 3 g TS/1 activated sludge (TS - total solids), which was processed in the 30 m high bubble columns, the so-called Tower Biology of BAYER AG/Leverkusen, Germany. 

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