摘要:

AbstractDuring recent years the air stripping process has been increasingly applied to the cleaning of water contaminated by volatile organic compounds (VOC). The present contribution compares various methods of treating VOC‐contaminated water, with a special focus on removal efficiency and economic aspects. In particular, air stripping, a universally used cleaning method, is described in greater detail. Design and operational aspects are worked out for packed stripping towers for the special case of water contaminated with chlorinated hydrocarbons. Experimental results substantiate predictions of various operating conditions, packing types and scale‐up effe

ISSN:0930-7516    

DOI:10.1002/ceat.270180302

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe flow of two immiscible liquids and the influence of an additional inserted gas phase in horizontal pipes is investigated. The experiments are carried out in a transparent horizontal pipe with an inner diameter of 59 mm and a total length of 48 m. Experimental results are presented for the flow regimes of the two phase and three phase flow of oil, water and gas mixtures. The effect of phase inversion on the pressure drop is measured. The experimental results obtained for the three phase flow of oil, water and air indicate that drag reduction is possible by injecting gas in laminar flowing mixtures of oil and water. In the aerated slug flow regime of oil, water and air a water dominated and an oil dominated flow system can be distinguished. The pressure drop of the three phase flow system is of the magnitude as the pressure drop of the two phase flow of gas and the dominating liquid phase.

ISSN:0930-7516    

DOI:10.1002/ceat.270180303

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractVenturi jet scrubbers are widely used in chemical industries as an efficient gas‐liquid contacting equipment. They are simple in design, have no moving parts, operate with circulating liquid and are reliable in service. Moreover, due to high relative velocity of liquid and gas, considerable overall mass transfer can be produced. In spite of their wide application, readily usable design data are not available in literature, particularly for units producing a gas flow by their own pumping action. The purpose of this paper is to introduce the equipment and its application for H2S removal. The effects of various parameters such as gas and liquid flow rates as well as pressure on hydrodynamics and mass transfer performance of the equipment are investigated. Results of experiments have been shown graphicall

ISSN:0930-7516    

DOI:10.1002/ceat.270180304

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractIn condensers with high condensation rates or in falling film evaporators the falling film at the vertical tube wall shows a turbulent flow pattern. For optimal dimensioning of these apparatuses the knowledge and the description of the heat transfer in this turbulent falling film is necessary. Especially in fluids with a low thermal conductivity in liquid phase (i.e. hydrocarbons) the main heat transfer resistance is in the falling film, also if there are several components in gas phase. For calculating the heat transfer usually dimensionless Nusselt equations were used. These equations mainly base on experimental results which were found with water vapour as test fluid. It is shown that these equations fail for fluids with low thermal conductivity resp. high Prandtl numbers. Based on a Nusselt equation for turbulent tube flow a new equation for turbulent film flow is derived. A comparison between calculated and measured data for Prandtl numbers up to 50 shows good agreement.

ISSN:0930-7516    

DOI:10.1002/ceat.270180305

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractAn approach to feedforward distillation control based on inverse computation of nonlinear stage models is presented. The feedforward model calculates dynamic trajectories of manipulated variables from measured disturbances and product purity set points independently of the control configuration. Because the model includes the dominant dynamics and nonlinearities of the column, dynamic decoupling of the control loops is achieved. A superimposed linear controller only has to compensate model uncertainties and disturbances that cannot be measured. The proposed approach improves the control performance. Simulation studies show the applicability of the method to multicomponent distillation as well as to distillation trains. Experiments on a pilot plant scale binary distillation column verify the simulation results.

ISSN:0930-7516    

DOI:10.1002/ceat.270180306

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe mass spectrometer is capable of making rapid, repetitive multicomponent analyses with measurement times as short as a second or less. Mass spectrometers used to be too expensive to be used for process analyses, but simpler and cheaper versions have been developed during the last decade. Mass spectrometers are commonly used within the petrochemical industry, but their use for fuel gas streams is not so widespread. This paper describes tests on a quadrupole mass spectrometer in three different gasification projects. Calibration methods and analysis accuracies obtained are accounted for. On the basis of the tests, it can be concluded that the quadrupole mass spectrometer is very suitable for continuous analysis of complex process streams. An important result is that the separation of CO and N2, an analysis problem that is traditionally regarded as difficult, worked very well. The analysis frequency was approximately once per minute, which should be enough for most control loops.

ISSN:0930-7516    

DOI:10.1002/ceat.270180307

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe vapour‐liquid equilibria of the binary systems perfluoromethylcyclohexane‐pentafluorobenzene, benzene‐pentafluorobenzene, benzene‐methylperfluorobutanoate and perfluoromethylcyclohexane‐methylperfluorobutanoate have been measured at 333.07 K and 343.12 K using a dynamic circulation still of the Sieg‐Röck type. The thermodynamic consistency of the measurements was tested by two different methods. New UNIFAC interaction parameters [1] were calculated for the following groups: ACH‐ACF, ACF‐CF2, CF2‐COO, ACCH2‐ACF, ACH‐CF2. The abbreviations stand for the following increments: ACH = aromatic CH group, ACF = aromatic CF group, CF2= aliphatic CF2group, COO = ester group and ACCH

ISSN:0930-7516    

DOI:10.1002/ceat.270180308

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractAn experimental set‐up is presented for the measurement of reaction rates in the liquid phase synthesis of tertiary amyl methyl ether (TAME) from methanol and a mixture of 2‐methyl‐1‐butene and 2‐methyl‐2‐butene using an acidic ion exchange resin (Lewatit SPC 118) as catalyst. The reaction was performed in a continuous‐flow recycle reactor at a temperature of 333.15 K and a pressure of 1.6 MPa. Determination of the age distribution (Fcurve) of the reactor showed that mixed flow is approached at a recycle ratio ofR= 10. Experiments were performed to reveal the limits of operating conditions where the various resistances do not affect the rate. In agreement with estimation of Reynolds numbers, hindrance by external mass transfer can be excluded at a volumetric flow rate of 10 ml/min and a recycle ratio ofR= 10. The maximum temperature increase of the whole particle resulting from limitation of external heat transfer was estimated to be about 3 K. Variation of the size of resin particles revealed the existence of a critical methanol concentration, above which reaction rates can be determined without influence of internal mass transport phenomena. The maximum temperature increase in the particle was estima

ISSN:0930-7516    

DOI:10.1002/ceat.270180309

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper describes an original system for automated solid‐phase peptide synthesis (SPPS) that was developed in our laboratories. The synthesizer is equipped with separate activator and batch reactors, and was designed to operate under either manual or computer control. Two metering pumps, which constitute the core of the entire apparatus, provide for the delivery and transfer of reagents and solvents in the appropriate quantities and in the correct sequence, and permit simultaneous condensation and activation operations that result in considerable time saving. Various applications to the synthesis of biologically important peptides, utilizing the most widely used strategies in SPPS, are presented as examples of this improved technolog

ISSN:0930-7516    

DOI:10.1002/ceat.270180310

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractA kinetic model of the oxidative coupling of methane (OCM) over lanthanum oxide is developed on the basis of mechanistic conclusions obtained elsewhere. A reaction scheme is proposed, and the kinetic parameters corresponding to the different kinetic equation are optimized. Experimental and calculated reaction rates are compared with the aim of testing the proposed scheme and validating the basic mechanistic assumptions.

ISSN:0930-7516    

DOI:10.1002/ceat.270180311

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY