Single-column system

A single-column system for liquid-phase carhon adsorption is used in situations where the following conditions prevail laboratory testing has indieated that the breakthrough curve will be steep the extended lifetime of the earbon at normal operating conditions results in minor replacement or regeneration eosts the eapital... 

The simplest air separation device is the Linde single-column system, which utilizes the simple Linde... 

Parameters for racemisation kinetics and chromatographic separation of a model system were determined experimentally. Model predictions and first-stage experiments were performed for flowsheet integrated processes. Single-column systems were found to be an interesting alternative to SMB-based schemes. 

To overcome problems associated with moving solid stationary phase materials, SMB operation fixes the location of the stationary phase and changes the feed and regenerant entry points and the raffinate and product removal points with time. Single- and multicolumn SMB systems are in use. Humphrey and Keller instruct that the single-column system is favored economically when processing feed flows over 50 million Ib/yr, while the multicolumn system is favored for processing lesser feed amounts. 

It may be necessary to compare overall capital and operating costs to determine which type of crude scheme is best for a given situation. Occasionally a refiner will convert a single-column system to two columns as a means of expanding throughput. 

Critical Bed Depth In a carbon column the critical bed depth is the depth of granular carbon that is partially spent. It lies between the fresh virgin carbon and the spent carbon, and is the zone where adsorption takes place. In a single-column system this is the amount of carbon that is not completely utilized. 

Column switching enables analyses to be carried out which are either impossible to achieve on a single column system or do not yield the required information using conventional methods. Switching of the carrier gas is achieved using multiport gas switching valves. These are used to switch the... 

Figure 8. Synthesis of CoA on an immobilized cell column. (A) Single column system a substrate mixture composed of sodium pantotheruite (2,5 fimol/mL), cysteine (10 nmoUmL), ATP (15 fxmoHmL), magnesium sulfate (10 imol/mL), potassium phosphate buffer, pH 6.5 (150 nmol/mL), and sodium laurylsulfate (1 mg/mL) teas applied to a column (1 X 20 cm) of gel-entrapped dried cells. The reaction was carried out at 34°C with a flow rate of SV = 0.1-O.2 hr h (B) Separated column system a substrate mixture composed of sodium pantothenate (2.5 /imol/mL), ATP (7.5 ixmol/mL), magnesium sulfate (10 nmol/mL), potassium phospate buffer, pH 6.5 (150 fimol/mL), and sodium laurylsulfate (1 mg/mL) was applied to the top of the column (1 X 10 cm). Solution (about 20 mh) passed through the column at a flow rate of SV = 0.1-0.2 hr t was collected every day. To the solution (20 mL), 200 nmol cysteine and 150 fimol ATP were added, which was then reacted at the bottom of the column (1 X 10 cm) with a flow rate of SV = 0.1-0.2 hr to yield CoA. The reaction temperature was 34°C. Consumption of pantothenic acid was checked both at the top (b) and bottom (a) columns.

In most ion-exchange installations, the vertical column is the most commonly employed unit. The system may consist of a single column with one type of resin (single column system), two or more columns containing a variety of cation and/or anion exchange resins (multiple-bed system), or a single column containing a mixed bed of two (or more) resins (monobed or mixed-bed system). 

FIGURE 5.64 Water softening by ion-exchange in single-column system. 

With the single column system it is not possible to produce pure methanol of Grade A or even AA under economically justifiable conditions, and it can therefore be used only in plants which are scheduled to turn out methanol for burner fuel or motor fuel applications. 

In the case of ion chromatography without a suppressor the resolving property of the column can be adapted to the particular analysis in question by a simple change of eluent. Fig. 69 shows a schematic representation of the possibilities for anion separation offered by a single-column system of this type. 

The flow rate of the eluent is 1.0 ml/min for a three connected column system, 0.60 ml/min for a two connected column system and 0.50 ml/min for a single column system, unless otherwise noted in the text. The separation of lipoproteins by HPLC is performed at ambient temperature. 

AIR SEPARATION SYSTEMS 6.4.1. Linde Single-Column System... 

The Linde single-column system introduced in 1902 is the simplest air-separation system used. In this scheme, shown in Fig. 6.23, water vapor and carbon dioxide are removed from the air after the latter has been compressed isothermally. The air then passes through a precooling heat exchanger. This... 

The Linde double-column system was introduced in 1910 to solve the problem of oxygen losses in the nitrogen stream of the Linde single-column system. As noted earlier, the maximum purity of the top product in the single column is approximately 94 mol % nitrogen. If this purity had been attained in Example 6.12, nearly 25% of the oxygen in the feed would have been removed in the top product. 

The double-column system works like the single-column system except for the addition of the rectification section. In the double-column system, entering air is introduced in the middle of the lower column instead of at the top. Part of the liquid nitrogen product stream from the lower column is throttled to the operating pressure of the upper column and sent to the top of the upper column as reflux. The enriched liquid air from the lower reboiler is also throttled and introduced as feed into the middle of the upper column. Depending on the number of plates used, any practical purity level of either or both components may be obtained. When extremely high-purity products are desired, the argon present in the air must be considered as a third component of the mixture and removed in a draw-off stream from the upper column." The operation of such a column can best be shown with the aid of an example. 

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