Online Characterization of Syngas Particulates Using Aerosol Mass Spectrometry in Entrained-Flow Biomass Gasification

Entrained flow gasification is a promising technique where biomass is converted to a synthesis gas (syngas) under fuel-rich conditions. In contrast to combustion, where the fuel is converted to heat, CO₂, and H₂O, the syngas from gasification is rich in energetic gases such as CO and H₂. These compounds (CO and H₂) represent the building blocks for further catalytic synthesis to chemicals or biofuels. Impurities in the syngas, such as particulates, need to be reduced to different levels depending on the syngas application. The objective of this work was to evaluate the amount of particulates; the particle size distribution and the particle composition from entrained flow gasification of pine stem wood at different operating conditions of the gasifier. For this purpose, online time resolved measurements were performed with a soot particle aerosol mass spectrometer (SP-AMS) and a scanning mobility particle sizer (SMPS). The main advantage of SP-AMS compared to other techniques is that the particle composition (soot, PAH, organics, and ash forming elements) can be obtained with high time resolution and thus studied as a direct effect of the gasifier-operating conditions. The results suggest that syngas particulates were essentially composed of soot at these tested process temperatures in the reactor (1200–1400°C). Furthermore, the AMS analysis showed a clear correlation between the amounts of polycyclic aromatic hydrocarbons (PAH) and soot in the raw syngas. Minimization of soot and PAH yields from entrained flow gasification of wood proved to be possible by further increasing the O₂ addition.

Copyright 2014 American Association for Aerosol Research     

Design configuration with architectural objects: linking customer requirements with system capabilities in industrialized house-building platforms

There are two main routes for customers of industrialized house building to follow: either rigid platforms offering preconfigured products, often called ‘type houses’, or more flexible platforms open to customization. The problem in customization is to link customer requirements with system opportunities. In axiomatic design processes, this problem is understood as the transformation of customer requirements in the architectural view into design parameters that are supported by the system. A new method is proposed that allows requirements and constraints of an industrialized building platform to be handled fully in the architectural view through configuration with so-called architectural objects. It is based upon established theories and complies with the rationale of separating platform development from product customization. An experimental study, using standard building information modelling software, shows that a hierarchical structure of architectural objects can support both the development, as well as the configuration process, of the platform. Modularization in the architectural view is believed to be an important first step to capturing user requirements in the development of platforms for a specific market segment. It is also anticipated that if these requirements can be conceptualized as architectural objects the capabilities in different configurator solutions can be made more transparent to the customer.     

An Extended Method to Measure Overall Consumer Satisfaction with Packaging

There are several reasons why people find it troublesome to use and handle consumer packages. The European Committee for Standardization recently suggested a technical specification (TS) regarding packaging and ease of opening. The present study has expanded the procedure by including consumer satisfaction measurements in two steps and engaging panels comprising two separate age groups. The expanded method, which used six different packages as test objects, engaged 75 panellists, 40 in the older group (65–80 years) and 35 in the younger group (25–40 years). The expanded method not only included the same operations as described in the TS but also included panellists who graded each handling element separately on a ‘smiley’ scale, along with feedback for their grades and an overall judgement of the package handling. The grading feedback differed between the two groups. The younger panellists mainly noted issues that were not connected to openability, while older panellists noted openability as the most influential factor. Further analysis revealed that openability was also a key issue for the younger panellists, despite their claims to the contrary. Satisfaction was the most critical TS element for describing a package as being easy to open. Copyright © 2014 John Wiley & Sons, Ltd.     

GaAs/AlGaAs heterostructure nanowires studied by cathodoluminescence

In this report we explore the structural and optical properties of GaAs/A1GaAs heterostructure nanowires grown by metalorganic vapour phase epitaxy using gold seed-particles. The optical studies were done by low-temperature cathodo- luminescence （CL） in a scanning electron microscope （SEM）. We perform a systematic investigation of how the nanowire growth-temperature affects the total photon emission, and variations in the emission energy and intensity along the length of the nanowires. The morphology and crystal structures of the nanowires were investigated using SEM and transmission electron microscopy （TEM）. In order to correlate specific photon emission characteristics with variations in the nanowire crystal structure directly, TEM and spatially resolved CL measurements were performed on the same individual nanowires. We found that the main emission energy was located at around 1.48 eV, and that the emission intensity was greatly enhanced when increasing the GaAs nanowire core growth temperature. The data strongly suggests that this emission energy is related to rotational twins in the GaAs nanowire core. Our measurements also show that radial overgrowth by GaAs on the GaAs nanowire core can have a deteriorating effect on the optical quality of the nanowires. Finally, we conclude that an in situ pre-growth annealing step at a sufficiently high temperature significantly improves the optical quality of the nanowires.     

Pretreatment methods for gasification of biomass and Fischer–Tropsch crude production integrated with a pulp and paper mill

In this paper, the influence on the system performance and greenhouse gas (GHG) emissions of different biomass pretreatment methods before gasification and Fischer–Tropsch (FT) crude production was evaluated. Entrained flow gasification has the benefit of producing a practically tar-free synthesis gas with nearly complete carbon conversion. This gasifier type requires a relatively dry fuel, with small particle size, at high pressure. The size can be acquired by milling, which is energy intensive and feeding is challenging. Torrefaction of biomass facilitates milling; it thus requires less electricity, however, the torrefaction process requires heat. Pyrolysis decomposes the biomass into gaseous, liquid, and solid parts, respectively. This further makes feeding easier, but comes with a greater heat demand than torrefaction. The impact of the different pretreatment methods on the overall energy system has been evaluated using process integration methodology. The results show that the excess heat from an FT process with a biomass input of 300 MW_HHV can replace the bark boiler in a large chemical pulp and paper mill, producing 350,000 tonnes of bleached paperboard annually. With the preconditions given for this study, thermal pretreatment of biomass may be beneficial in terms of wood-to-FT crude efficiency, with efficiencies up to 68 %, assuming 40 % electrical efficiency. Pretreatment using pyrolysis performed the best in regards to GHG emissions, if CO₂ from acid gas removal was vented, while milling, with an annual reduction of around 700,000 tonnes of CO₂,_eq, had the best results if the CO₂ was captured and sequestrated.     

Applying California's AB 32 targets to the regional level: A study of San Diego County greenhouse gases and reduction strategies

This paper presents a summary of a local effort in California to assess greenhouse gas (GHG) emissions and identify potential mitigation measures. Local policymakers in California already have been searching for ways to reduce GHG emissions but it was the California Global Warming Solutions Act of 2006 (AB 32), which seeks to reduce GHG emissions to 1990 levels by 2020, that has provided a framework for regions to evaluate their ability to reduce GHG emissions. We conducted a GHG inventory for the San Diego region from 1990 to 2006, with forecasts to 2020. The region emitted approximately 34 million metric tons of carbon dioxide equivalent (MMT CO₂E) in 2006 from anthropogenic sources, which represents a 17% increase over the 1990 level of 29 MMT CO₂E. Applying a combination of 21 existing or pending state GHG reduction mandates and feasible regional measures we show that the region could achieve the AB 32 target. Although the largest reductions are achieved through state mandates, all measures, including at the local level, will be required to achieve the AB 32 target. Thus local regions retain control over a fairly significant portion of reductions, and remain important actors in the implementation and compliance of state mandates.     

A COMPARISON OF THE HYDRODYNAMICS OF OPEN AND CLOSED STIRRED VESSELS

In this study, the effect that the top boundary has on the flow in the bottom region of a fully baffled stirred vessel of standard geometry, was investigated. Measurements of the three dimensional mean and fluctuating velocity components were made with Laser Doppler Anemometry. Calculations of the flow field were made with the commercially available CFD code FLOW3D. Three cases were studied. Two in which the top boundary was located at 30 mm, one with an air-liquid interface (open vessel) and one without (closed vessel). For the third case a closed vessel was also used and the top boundary was located at 150 mm.

The effect of removing the air-liquid interface at 300 mm on the flow in the bottom region of the vessel was small enough to be within the experimental uncertainty. Lowering the closed top boundary from 300 to 1 SO mm had a rather small impact on the flow field in the lower part of the vessel, It was concluded that the detected change is due partly to a direct effect from the introduced lid and partly to the fact that the impeller discharge is affected. The observed changes are so small that it can safely be stated that the suspension capacity of the system is not affected when the top boundary is altered within the limits of the present investigation.     

Macroscopic Entanglement and Phase Transitions

This paper summarises the results of our research on macroscopic entanglement in spin systems and free Bosonic gases. We explain how entanglement can be observed using entanglement witnesses which are themselves constructed within the framework of thermodynamics and thus macroscopic observables. These thermodynamical entanglement witnesses result in bounds on macroscopic parameters of the system, such as the temperature, the energy or the susceptibility, below which entanglement must be present. The derived bounds indicate a relationship between the occurrence of entanglement and the establishment of order, possibly resulting in phase transition phenomena. We give a short overview over the concepts developed in condensed matter physics to capture the characteristics of phase transitions in particular in terms of order and correlation functions. Finally we want to ask and speculate whether entanglement could be a generalised order concept by itself, relevant in (quantum induced) phase transitions such as BEC, and that taking this view may help us to understand the underlying process of high-T superconductivity. Presented at the 38th Symposium on Mathematical Physics “Quantum Entanglement & Geometry”, Toruń, June 4–7, 2006.     

Role of surface oxygen in the preparation and deactivation of carbon nanofiber supported cobalt Fischer–Tropsch catalysts

Surface oxygen groups on the carbon nanofiber surfaces are important for the preparation of highly dispersed cobalt catalysts and for the stabilization of the particles against sintering. However, the surface oxygen makes the catalysts easily deactivate during Fischer–Tropsch synthesis by oxidation of metallic cobalt. The activity could be recovered by re-reduction.