Stream Splitting Research Articles

On-line microbore high-performance liquid chromatography—capillary gas chromatography—mass spectrometry : II. Application to the analysis of solvent refined coal

A new on-line technique for the analysis of complex petroleum samples is presented employing a microbore high-performance liquid chromatography (HPLC) system for first-stage fractionation by ring size, directly coupled to a high-resolution capillary gas chromatography (GC) system for isomer separations, followed by an on-line mass spectrometer for identification. The use of microgore HPLC and a newly developed low-dispersion stream splitter permitted non-discriminative transfer of the fractionated LC zones directly to the gas chromatograph without the need for further LC miniaturization or retention-gap techniques on the gas chromatograph. The eluent splitter also allowed the simultaneous monitoring of the eluent for accurate zone sampling and transfer, and for the introduction of further separation dimensions such as LCLCGC—mass spectrometry (MS). The LCGCMS was applied to a solvent refined coal sample with the three- and four-ring fractions being separated and identified. Probability of the LCGC system to separate pure components ranged from 95 to 97% for the coal tar sample vs. to 7.0% for a single-stage, capillary GC separation.

Liquid chromatography-gas chromatography interfacing using microbore high-performance liquid chromatography with a bundled capillary stream splitter

Presentation de cette technique multidimensionnelle de separation des melanges complexes applicable a la separation des composants de liquides derives du charbon par extraction par solvant

Improved flow field-flow fractionation system applied to water-soluble polymers: programming, outlet stream splitting, and flow optimization.

Improved flow field-flow fractionation system applied to water-soluble polymers: programming, outlet stream splitting, and flow optimization.

Automatic synthesis of optimum heat exchanger network configurations

AbstractThis paper addresses the problem of automatically generating heat exchanger network configurations that feature minimum investment cost subject to minimum utility cost and fewest number of units. Based on the linear programming and the mixed‐integer linear programming (MILP) transshipment models for heat integration, a superstructure that has embedded many alternative configurations is proposed. This superstructure, which has as units the matches predicted by the MILP transshipment model, includes options for series and parallel matching, as well as stream splitting, mixing, and bypassing. Many of the implied stream connections in the superstructure are reduced to zero flow with a nonlinear programming formulation that leads to realistic and practical designs. Theoretical properties as well as the implementation aspects of the proposed procedure for the automatic generation of networks are presented. The method is illustrated with three example problems.

A NOTE ON THE MINIMUM NUMBER OF UNITS FOR HEAT EXCHANGER NETWORK SYNTHESIS

Although graph theory shows that the minimum number of exchangers (Umin) in a network is usually one less than the number of streams (N - 1), examples have been published, which demonstrate that this limiting case cannot always be achieved. Some of these examples contain a pinch point, for which it is advocated that the ‘N - 1 target’ should be applied on both sides of the pinch. However, by using a novel arrangement of stream splitting, mixing and by-passes, some of the literature examples can be designed to conform to the N - 1 target. For networks with similar total areas, those having fewer units will usually be cheaper, so Umin networks often have lower capital costs. Although the networks discussed here have somewhat larger total areas, possible applications are discussed where they may be economically attractive.

Optimized field-flow fractionation system based on dual stream splitters

Cette technique est recommandee pour les grandes vitesses, et des operations repetitives; elle reduit la duree de traitement

Stochastic simulation of residence time distribution curves

A stochastic approach, namely a Markov chain, has been employed to generate the residence time distribution (RTD) curves of various flow models. This technique is shown to be efficient and useful in modeling complex flow systems which consist of ideal mixing cells, plug flow zones, split streams, recycle streams and any combination of these for which the mathematical description is extremely difficult if not impossible. The expressions for the mean and variance of the residence time distributions for a flow system are elucidated from the stochastic viewpoint. Two examples have been simulated numerically; the agreement between the RTD's derived from the exact statistical treatment and those based on the present Markov chain approach appears satisfactory. The technique proposed in this study enables us to generate the RTD curve for any flow system and to match it to the experimental data. Furthermore, the applicability of the Markov chain approach for generating the cycle time distribution curve for a circulating system is discussed.

Effluent stream splitting to two different detectors

Effluent stream splitting to two different detectors

New simultaneous modular method for calculating multistage multicomponent separation processes

AbstractA new flexible method has been developed for modelling multistage multicomponent separation processes. The method is based on the simultaneous modular approach and can be referred to as a quasilinear two‐level modelling. The network is solved within each iteration as a linear one, and after each network solution the split streams are updated modularly using nonlinear submodels. The method is suited for modelling the most important separation processes with arbitrary structure and permits to use different models for the subunits or processing units. Illustrative examples and computational results are presented showing the efficiency, flexibility and capability of the method.

Outlet Stream Splitting for Sample Concentration in Field-Flow Fractionation

Abstract Retention in field-flow fractionation is a result of a field-induced sample concentration in the vicinity of a channel wall. By splitting the channel flow at the exit, so that sample containing flow lines leave the channel at a different port than those free of sample, one may markedly enhance the detectability of a given sample. The enhancement is discussed for the cases of “ideal splitting,” where an obstacle inserted in the flow stream affects the split, and “nonideal splitting,” where the flow is caused to split at some level in the channel specified by the relative resistance to flow through the two outlets. The proposed increase in detector response through stream splitting is experimentally verified.

A structural optimization approach in process synthesis—II

Several formulations of the transshipment model from Operations Research are proposed for the optimal synthesis of heat exchanger networks. The linear programming versions are used for predicting the minimum utility cost, and can handle restricted matches and multiple utilities. The mixed-integer programming version yields minimum utility cost networks in which the number of units is minimized, while allowing stream splitting and selection of most preferred matches. It is shown that the transshipment models can also be incorporated easily within a mixed-integer programming approach for synthesizing chemical processing systems. Several numerical examples are presented which show that the proposed models are computationally very efficient.

LCMS interfacing in sector mass spectrometers

The construction of a jet separator based LCMS interface which is compatible with magnetic sector instrument operation is described. Flow rates of up to 150μl minute −1 of aqueous solvents may be introduced without stream splitting or modification to the mass spectrometer. An evaluation of the sample handling capabilities of the interface is also presented.

Process simulation of an SRC-II plant

The paper describes the development of simulation of an SRC-II plant. The simulation considers all the significant units in the process flow sheet and also contains independent computational units to represent each combination or splitting of process streams. The simulation requires definition of only 6 independent variables to yield the specific flow rates and compositions of all the streams. The effect of changes in the values of the important variables on total liquid production rate and liquid yield is evaluated, and it is shown that by making relatively small changes in the operating conditions, the liquid production rate can be increased by more than 40% over those normally achieved. Difficulties in obtaining complete conversion of liquefiable organic matter in coal are discussed.

Quantitation of radiolabeled biological molecules separated by high-performance liquid chromatography

Several techniques are compared for the quantitation of radiolabeled molecules separated by high-performance liquid chromatography (HPLC). The first technique is the direct fraction collection of the HPLC eluent at pre-set times in individual tubes. Aliquots are removed from each tube, placed in scintillation vials, scintillation fluid is added and the radioactivity is counted in a liquid scintillation counter. The second technique is the direct interface (immediate analysis and plotting of data) of the eluent from the HPLC to a flow-through radioactivity detector. The third technique is to split the eluent from the HPLC with a microbore electronic stream splitter (flow/no flow) with a certain percentage directed to the flow-through radioactivity detector and the remainder collected in a fraction collector for further chemical chracterization (gas chromatography-mass spectrometry, recrystallization, further purification). A direct comparison of the chromatograms, radioactivity counting efficiencies and sensitivities for these three techniques is presented.

Reversed-phase liquid chromatography of peptides for direct micro-sequencing

Tryptic and cyanogen bromide peptides derived from yeast aspartyl-tRNA synthetase and from Escherichia coli ribosomal proteins were separated by reversed-phase liquid chromatography, employing volatile buffers of low ionic strength. The conditions used allow the performance of micro-sequencing without desalting or extensive lyophilization, and can therefore be applied to peptide mixtures containing hydrophobic fragments which tend to precipitate. To prevent losses of peptides, direct ultra-violet detection of the peptides was preferred, to detection by post-column derivatization with an additional stream splitting device. Preparative separations were performed with 5–10 nmol of peptide mixture; analytical runs were made with 5–10 μg of protein hydrolysate.

A PNEUMATIC FEEDER-SPLITTER SYSTEM FOR FLUIDIZED BED COMBUSTORS

Abstract One of the problems associated with the commercialization of Atmospheric Fluidized Bed Combustors (AFBC) is that of feeding coal-limestone mixtures into the bed without breakdown of the particles. Breakdown of the particles should be avoided in order to prevent the emission of inordinately large quantities of ash fines and the resulting heavy duty to the flue-gas cyclones. A system has been constructed which has successfully split individual streams of crushed walnut shells. limestone or coal from a 100 mm (4 inch) feedline to four 50 mm (2 inch) lines with minimal (10%) attrition and acceptable uniformity. The system consists of a horizontal section 10 meters long, followed by a vertical section 5 meters high at the top of which is affixed a four-way splitter cap. Samples are knocked out by cyclones in each of the four arms and analysed both for total weight and size distribution. Based on these and previous analyses some parameters have been set for the length of pneumatic conveying lines for f...

A Rapid Method of Quantitating Steroids Resulting from the Incubation of Gonadal Tissues with Radioactive Precursors

Abstract A rapid method has been developed for the quantitation of steroid metabolites resulting from the incubation of specific gonadal cell types or gonadal tissue with radioactive precursors. The method involves the use of high performance liquid chromatography (HPLC) for separating the steroids and a flow-through radioactive detector (Flo-One HP) for quantitating the radioactive 3H precursor and metabolites in the presence or absence of 14C-steroid recovery tracers. A comparison is made between the results obtained directly by the Flo-One HP radioactivity detector and the fraction collection method, (counting aliquots from individual fractions in the liquid scintillation counter). In addition, the results using an electronic stream splitter in the analysis of a percentage of the effluent directly by Flo-One HP are evaluated. The remaining percentage is collected in a fraction collector and is used for further analysis (e.g. recrystallization, RIA, further purification and characterization).

Evaluation of capillary gas chromatography for thermolabile phenylurea herbicides : Comparison of different columns including fused silica

The study reported was carried out first to define the possibilities and limitations of capillary gas chromatography (GC) for the analysis of phenylurea herbicides. Secondly, it was a useful means of studying the degradation of labile compounds on the column. Problems such as the detection of catalytic activity or the absence of a correlation of such activity with characteristics determined by known general testing procedures for assessing column quality are discussed. The analysis of intact phenylurea herbicides by capillary GC is possible for a restricted number of the more stable species. The compounds are degraded into the corresponding isocyanates upon thermal stress. Thin-film capillaries should be used to reduse elution temperature as far as possible. Further improvment may be achieved by using hydrogen as the carrier gas to minimize retention. The capillary column may promote the decay by catalytic activity. Barium carbonate columns and a Chrompack column caused moderately high degradation rates, but considerably less than a Carbowax deactivated fused silica column. Persilanized columns were found to be the most suitable. An optimized sampling technique using vapourising injection may cause relatively little degradation in the injector but, as this requires stream splitting, sensitivity is restricted. The precision and accuracy of this method are poor. Cold on-column sampling eliminates such problems.

Liquid-chromatographic separation and on-line bioluminescence detection of creatine kinase isoenzymes.

Abstract We separated isoenzymes of creatine kinase by anion-exchange chromatography, with use of an elution of gradient containing lithium acetate (0.1 to 0.6 mol/L). A stream splitter was used to divert a 5% side stream of column effluent, which was subsequently mixed with the reagents necessary for bioluminescence assay of the separated isoenzymes. The use of the stream splitter greatly decreased the rate of consumption of reagent and, when combined with a peristaltic pumping system, permitted independent control of the side-stream flow rate. Thus both the residence interval in a delay coil in which the ATP reaction product is formed and the bioluminescence response could be increased. Bioluminescence emission was monitored in a flow-through fluorometer without use of an external light source or filters. Separation and detection of the isoenzymes of creative kinase were rapid, sensitive, and highly selective. The incremental decrease of bioluminescence response owing to inhibition by the ions in the eluent was less than 31% across the entire gradient.

Liquid-chromatographic separation and on-line bioluminescence detection of creatine kinase isoenzymes.

We separated isoenzymes of creatine kinase by anion-exchange chromatography, with use of an elution of gradient containing lithium acetate (0.1 to 0.6 mol/L). A stream splitter was used to divert a 5% side stream of column effluent, which was subsequently mixed with the reagents necessary for bioluminescence assay of the separated isoenzymes. The use of the stream splitter greatly decreased the rate of consumption of reagent and, when combined with a peristaltic pumping system, permitted independent control of the side-stream flow rate. Thus both the residence interval in a delay coil in which the ATP reaction product is formed and the bioluminescence response could be increased. Bioluminescence emission was monitored in a flow-through fluorometer without use of an external light source or filters. Separation and detection of the isoenzymes of creative kinase were rapid, sensitive, and highly selective. The incremental decrease of bioluminescence response owing to inhibition by the ions in the eluent was less than 31% across the entire gradient.