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.     

4Cr5MoSiV1热作工具钢热形变组织模拟

建立4Cr5MoSiV1工具钢热变形过程的组织演化模型,以应用于DEFORM软件对其锻造过程进行全尺寸模拟.首先在大量热机械模拟实验数据的基础上,建立了基于Avrami方程的4Cr5MoSiV1工具钢奥氏体再结晶分数和再结晶晶粒尺寸计算模型,优化得到了模型的各项材料常数.对模型的预报结果与实验结果进行了对比验证,显示该模型的预测结果与实验结果具有良好的一致性,表明该模型及其优化后的参数可以应用于进一步热加工过程的全尺寸有限元模拟.     

Empirical to mechanistic modelling in high shear granulation

This paper gives an overview of the different models available for granulation in high shear mixers with a focus on applicability in the pharmaceutical industry. Three examples of applications are given. The examples indicate the potential of mechanistically based models for scale-up and the importance of understanding the dynamics of the granulation process. The first two examples show how the impeller torque can be modelled and predicted in the dry and wet mixing phases of the high shear granulation process, using a solid mechanics and a hierarchical multivariate model, respectively. In the third application the particle size distribution is modelled using population balances and it is shown how different operating conditions can be included in the coalescence kernel to describe the granule growth.     

Surface transformation of graphite or diamond following Highly Charged Ion irradiation

Highly Charged Ions (HCI) approaching surfaces at nm distances are known to extract a very large number of electrons from the target. Over dielectric surfaces, the positive holes left following the removal of the electrons cannot be immediately neutralized, thereby locally inducing a huge stress and creating permanent surface modifications on very small dots. We present in this paper experiments on the structural transformations induced by irradiation with HCI of graphite and diamond surfaces characterized using the Atomic Clock Property of the Hollow Atoms (ACPHA) technique.     

Oxidative Stability of Liposomes Composed of Docosahexaenoic Acid-Containing Phospholipids

Oxidative stability of liposomes made of (Docosahexaenoic acid) DHA-containing phosphatidylcholine (PC) was examined during preparation and storage. After preparation of the liposomes, the concentration of primary (conjugated dienes) and secondary oxidation products (Thiobarbituric acid-reactive substances, TBARS) were significantly higher compared to the initial value. During cold storage, formation of conjugated dienes and TBARS remained more or less constant in large unilamellar vesicles (LUV), whereas in mulitilamellar vesicles (MLV) they were seen to increase over a period of 21 days. Evaporation of solvent traces from a lipid film should preferably be done under nitrogen as vacuum evaporation was found to increase oxidation of the phospholipid.     

Local Signatures of High-Tc Superconductivity Possible Origin of the Pseudogap

We have studied buffer ions induced holes clustering in the CuO ₂ plane by means of embedded cluster quantum chemistry calculations. This instability is suggested by Raman spectroscopy to be characteristic of the pseudo-gappedfermi surface at T