Loop-type liquid

The SSC-K is based on the methods and models of SSC-L [5], which was originally developed to analyze loop-type liquid metal reactor transients. Because of the inherent difference between the pool and loop designs, major modification to the SSC-L has been made for the analysis of the thermal hydraulic behaviour within a pool-type reactor. Now, the SSC-K code has the capability to analyze both, loop and pool type liquid metal cooled reactors. 

Coupled liquid chromatography-gas chromatography is an excellent on-line method for sample enrichment and sample clean-up. Recently, many authors have reviewed in some detail the various LC-GC transfer methods that are now available (1, 43-52). For the analysis of normal phase eluents, the main transfer technique used is, without doubt, concurrent eluent evaporation employing a loop-type interface. The main disadvantage of this technique is co-evaporation of the solute with the solvent. 

One of the first examples of the application of reverse-phase liquid chromatography-gas chromatography for this type of analysis was applied to atrazine (98). This method used a loop-type interface. The mobile phase was the most important parameter because retention in the LC column must be sufficient (there must be a high percentage of water), although a low percentage of water is only possible when the loop-type interface is used to transfer the LC fraction. The authors solved this problem by using methanol/water (60 40) with 5% 1-propanol and a precolumn. The experimental conditions employed are shown in Table 13.2. 

The catalysts most frequently used are based on noble metals (mainly palladium and platinum) on various supports, or on nickel catalysts (mainly Raney type). Hydrogenations are generally performed in the liquid phase, under relatively mild conditions of temperature and pressure (1—40 bar). Most processes are performed batch-wise using powder catalysts in stirred tank or loop-type reactors with sizes up to 10 m . 

Sodium superheat experiments were performed in a forced-convection facility employing system parameters in the range of interest for application to loop- and pot-type liquid metal-cooled fast breeder reactors (LMFBRs). The test section was... 

The injector system is often of the loop type. Here the main solvent delivery tube to the column top is by-passed in a loop, which may be isolated and depressurised, and injected with sample via a septum. After injection the liquid in the loop is released into the main solvent flow. The loop volume is of comparable capacity to the injection volume. Most instruments are designed for autosampling in the case of multiple analyses, the operation being controlled by the instrument software. 

Liquid chromatograph. The instrument should be one that is designed for use with stainless steel columns and is equipped with a pumping system able to maintain a pressure of 15 MPa a UV spectrophotometer detector able to measure UV absorbance at 254nm and a loop-type injector. 

The adsorption isotherm starts at a low relative pressure. At a certcdn minimum pressure, the smallest pores will be filled with liquid nitrogen. As the pressure is increased still further, larger pores will be filled and near the saturation pressure, all the pores are filled. The total pore volume is determined by the quantity of gas adsorbed near the saturation pressure. Desorption occurs when the pressure is decreased from the saturation pressure. The majority of physisorption isotherms may be grouped into six types [9]. Due to capillary condensation, many mesoporous systems exhibit a distinct adsorption-desorption behaviour which leads to characteristic hysteresis loops (Type IV and V isotherms) whose shape is related to pore shape. Type I isotherms, characterised by a plateau at high partial pressure, are characteristic of microporous samples. A typical isotherm, representative of a mesoporous sample is given in Fig. 4.6, with a schematic representation of the adsorption steps. 

Concurrent eluent evaporation is most commonly performed with the loop-type interface (Figure 4) the liquid is pushed into the oven-thermostatted precolumn by the carrier gas and stopped there by its... 

Hankemeier et al., studied large-volume injection combined with GC/DD-FTIR. A loop-type injection interface was chosen because of its rather simple optimization. Large-volume injection by means of a loop-type interface can be carried out successfully in conjunction with GC/DD-FTIR. The hyphenation permits enhanced detectability of analytes by about two orders of magnitude when compared with conventional split/splitless ones. As demonstrated, the determination and identification of PAHs in river water is possible down to a level of 0.5 p-g/L, even when using simple micro hquid-liquid extraction as a sample preparation technique. The present system may, therefore, be considered a viable approach to trace-level environmental analysis. 

When a liquid system is used, it should be the closed-loop type, with each zone on separate instruments for more accurate control. The closed-loop system uses treated water to reduce the possibility of contamination. Plant water is passed... 

Class B1 systems show closed loop vapour/liquid pressure/composition diagrams in the vapour liquid region at all temperatures between the solvent critical temperature and the critical temperature of the heavy component. The system ethane/methanol shows this behaviour. Carbon dioxide/w-hexadecane is probably also of this type (Figure 1.10 and 1.11). 

G. D. Anderson s article recommends initial controller settings for those control loops set on automatic rather than manual for a plant startup. For liquid level, the settings depend upon whether the sensor is a displacer type or differential pressure type, or a surge tank (or other surge) is installed in the process ... 

Thermal Expansion in Flare Header - Sliding-type expansion joints may be used in flare headers as an alternative to piping expansion loops, if required to achieve a reduction in pressure drop or where expansion bends may result in liquid surging, subject to the following conditions ... 

Loop Tests Loop test installations vary widely in size and complexity, but they may be divided into two major categories (c) thermal-convection loops and (b) forced-convection loops. In both types, the liquid medium flows through a continuous loop or harp mounted vertically, one leg being heated whilst the other is cooled to maintain a constant temperature across the system. In the former type, flow is induced by thermal convection, and the flow rate is dependent on the relative heights of the heated and cooled sections, on the temperature gradient and on the physical properties of the liquid. The principle of the thermal convective loop is illustrated in Fig. 19.26. This method was used by De Van and Sessions to study mass transfer of niobium-based alloys in flowing lithium, and by De Van and Jansen to determine the transport rates of nitrogen and carbon between vanadium alloys and stainless steels in liquid sodium. 

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