Cold Rich Bypass to Strippers for CO2 Capture by Concentrated Piperazine

Cold rich bypass to the stripper in CO₂ capture by alkanolamines will usually reduce the total heat duty. Bypass reduces the stripping steam in the overhead vapor and balances the temperature approach in the main cross exchanger. This process improvement reduces the energy requirement of any configuration, but it is most beneficial when the overhead vapor is not already countercurrently contacted with incoming rich solution. Therefore, the 2‐stage flash configuration was evaluated in this work, and it had an improvement of 11 % over the no bypass case. Its improvement was better than what was observed with a simple stripper and interheated column. An optimized cool rich bypass for a pilot scale 2‐stage reduces the equivalent work.     

Magnetic quadrupole doublet focusing system for high energy ions

A high energy focused ion beam microprobe using a doublet arrangement of short magnetic quadrupole lenses was used to focus 1-3 MeV protons to spot sizes of 1x1 microm2 and 1-4.5 MeV carbon and silicon ion beams to spot sizes of 1.5x1.5 microm2. The results presented clearly demonstrate that this simple doublet configuration can provide high energy microbeams for microanalysis and microfabrication applications.     

Multiphysics simulation on electromagnetic peening of predrilled holes

The areas around predrilled holes are highly stressed regions where cracks can easily form, which decreases the resistance of metal components to fatigue and causes serious problems in industry, such as aerospace, automobile, and ship building. In this paper, a novel method utilizing the effects of a strong pulsed electromagnetic field is introduced to effectively produce residual compressive stress into the surface of a predrilled hole. Basic principles of electromagnetic peening (EMP) are investigated using a multiphysics simulation approach. Simulations of EMP process on the surface of a work piece with predrilled blind hole are carried out by COMSOL Multiphysics 3.4. The distributions of stress and strain are presented and discussed, which demonstrate the feasibility of EMP on inducing compressive residual stress into the interior surface around a hole. In addition, the distribution of residual stress varies with various hole depth and work piece thickness is investigated. Finally, the influence of process parameters is also studied. The results of this work will help design process of strengthening 3D surfaces in metal components in manufacturing industry.     

Qualification of a fluorescence spectrometer for measuring true fluorescence spectra

New analytical methods using fluorescence detection are becoming increasingly quantitative and require easy-to-use material standards for fluorometer qualification and method validation. NIST is responding to this need by developing and producing such standards. Reported here is the first step in this process, which is to qualify a research-grade fluorescence spectrometer for measuring true fluorescence spectra of reference material candidates. "True" spectra are defined here as those with fluorescence intensity, either relative or absolute as required, and wavelength both being reported with high accuracy and known precision, after wavelength has been calibrated and corrections for excitation intensity and detection system response have been applied. The uncertainties determined in relative and absolute intensity-corrected fluorescence spectra using both calibrated source (CS)- and calibrated detector (CD)-based methods were compared. The CS-based method gave uncertainties, typically about +/-5% for relative spectral correction, that were about half that of the CD-based method for determining both relative and absolute spectral correction factors. Absolute spectral correction factors can be determined using either method without knowing the optical geometry of the instrument. The absolute spectral correction factors were found to have much larger uncertainties than the corresponding relative correction factors with uncertainties for the CS-based method of +/-10% to +/-15% being typical and +/-20% or more not being uncommon, particularly for excitation and emission wavelengths below 400 nm. Uncertainties arising from detection system nonlinearity and instrument polarization ratios were also explored.     

Optimisation of four-sensor probes for measuring bubble velocity components in bubbly air-water and oil-water flows

In a previous paper Lucas and Mishra (2005) [3] a local four-sensor conductance probe was introduced to measure the velocity vectors of dispersed bubbles in bubbly two-phase flow in which the continuous phase is water. There are a very limited number of alternative methods available for bubble velocity vector measurement with which results from, for example, computational fluid dynamic models can be compared and so the four-sensor probe technique is of interest to the multiphase flow community. In the previous paper [3] a mathematical model was presented to calculate the velocity vector of each gas bubble from seven time intervals which were measured using the output signals from each of four ‘needle’ conductance sensors located within the probe. In the present paper, a new technique for making the local four-sensor probe is introduced to minimise interference with the measured bubbles. A new signal processing method is presented using criteria to ensure that (i) the group of sensor signals from which the bubble velocity vector is to be determined are all produced by the same bubble and (ii) bubbles which contact the local four-sensor probe in an ambiguous manner are ignored. The accuracy with which the locations of each of the rear sensors in the probe relative to the lead sensor can be measured influences the accuracy with which the bubble velocity vector can be measured. However, the degree to which the accuracy of the measured velocity vector is affected by errors in the measured probe dimensions is dependent upon the geometrical arrangement of the four sensors within the probe. Experimental results and an error analysis are presented which show that the susceptibility of the velocity vector measurement technique to errors in the measured probe dimensions is reduced if the geometrical arrangement of the four sensors is optimised. As a result of this initial work, an optimised probe, known as the P30 probe, was designed and built and results obtained from the P30 probe in swirling oil-in-water bubbly flow are presented. A probe calibration factor is defined in this paper which can be interpreted as a measure of the interference of a probe with the motion of the bubbles with which it interacts. For the probes described in this paper the calibration factor was found to be much closer to unity than for previous four-sensor probes described in the literature (e.g. [3]) suggesting that these new probes have a much smaller effect on the bubbles’ motion than previous probes.     

In situ, noninvasive characterization of superhydrophobic coatings

Light scattering was used to measure the time-dependent loss of air entrapped within a submerged microporous hydrophobic surface subjected to different environmental conditions. The loss of trapped air resulted in a measurable decrease in surface reflectivity and the kinetics of the process was determined in real time and compared to surface properties, such as porosity and morphology. The light-scattering results were compared with measurements of skin-friction drag, static contact angle, and contact-angle hysteresis. The in situ, noninvasive optical technique was shown to correlate well with the more conventional methods for quantifying surface hydrophobicity, such as flow slip and contact angle.     

A two surface plasticity model for the simulation of uniaxial ratchetting response

In this study, a two surface plasticity model was developed and used to simulate the uniaxial ratchetting response of CS 1026 steel. Most cyclic plasticity models used in ratchetting simulations are Chaboche-type nonlinear kinematic hardening models, which deal with dynamic recovery terms considering the back stress tensor. This paper describes the ratchetting simulation of steel by the two surface model based on yield theory following both isotropic and kinematic hardening rules in order to obtain enhanced ratchetting response. The parameters used in the simulation were obtained from a parametric study and were determined from the initial range and stabilized range of CS 1026 steel. In addition, the two surface model was validated by comparing the results of a ratchetting simulation with experimentally determined maximum axial strain per cycle. The ratchetting responses obtained from the two surface model are an improved simulation results compared with results from bilinear and kinematic hardening models.     

Empirically and Theoretically–Based Models for Predicting Brominated Ozonated By–Products

During water treatment, ozonation of waters containing bromide ion producesboth organic and inorganic disinfection byproducts. Bromide ion concentrations in U.S. waters range from 0.01 to 2 mg/L (Krasner, 1989). Bromoformand dibromoacetic acid (DBAA) are the major organic byproducts and bromateion is the major inorganic byproduct derived from ozonation. Bromoform is a known carcinogen and the existence of bromate ion in water supplies also is of public health concern (Lykins, 1986). Bromate ion causes renal failure and hearing loss in laboratory animals and in human beings (Kruithof, 1992). The provisional guideline for bromate ion as proposed by the World Health Organization is 25 pg/L and may be exceeded in water treatment processesusing ozone. Also draft drinking water regulations in the U.S. will specify a maximum contaminant level (MCL) of 10 µg/L for bromate ion and a bestavailable treatment (BAT) of pH adjustment.     

Studies of water-soluble oligomers formed in emulsion copolymerization

A polymer chain transfer agent was synthesized by the reaction between poly(vinylbenzyl chloride) latex particles and 2-aminoethanethiol in a basic environment. In subsequent emulsion polymerization reactions, low molecular weight species were formed when waterborn oligomeric radicals diffused to the surface of these seed particles. These low molecular weight oligomers were separated by membrane filtration and their composition and molecular weight weight were analyzed by FTIR and mass spectroscopy. The measured composition results were compared with those that were calculated from the copolymerization equation. The molecular weights were compared with earlier experimental results that were obtained by isolation of oligomers formed when a water-soluble inhibitor was added to a reacting emulsion. Three seeded emulsion copolymerization systems, that is, styrene–acrylic acid, styrenemethacrylic acid, and styrene–methyl methacrylate, were investigated. The distribution of monomer in the water phase and in the copolymer particles was analyzed. The results show that the oligomer compositions for different copolymerization systems can be approximated reasonable well by the copolymerization equation, using the reactivity ratios obtained from bulk copolymerization. The length of the oligomer radicals formed depends on their composition and the properties of the polymer particles, such as surface charge, composition, size, and concentration. © 1994 John Wiley & Sons, Inc.     

On the communication of measurement results

In recent times there have been a number of suggestive attempts to formulate a semiotics of measurement in the context of modern theory and practice of instrumentation. All have been critically reliant on one of the most ancient theories of language – the picture or model or representational theory of meaning. Modern linguistics has concluded that the representational model is important but only part true. In this paper, a complementary approach is suggested based on the empirical observations of James Clerk Maxwell and approaches to pragmatic linguistics involving intentional system behaviour, which stem from a famous discussion of meaning in 1955, by H. P. Grice. Application of Gricean effectiveness conditions for the communication of measurement results yields conditions relevant to traceability and the aims of accreditation practices. They underscore an essentially ethical dimension to modern metrology – that, as others have put it, measurements ought to be what they purport to be. It is increasingly necessary that they also be seen to be both what they purport to be, and fit for purpose.